Commit Graph

915753 Commits

Author SHA1 Message Date
Cédric Le Goater
b1f9be9392 powerpc/xive: Enforce load-after-store ordering when StoreEOI is active
When an interrupt has been handled, the OS notifies the interrupt
controller with a EOI sequence. On a POWER9 system using the XIVE
interrupt controller, this can be done with a load or a store
operation on the ESB interrupt management page of the interrupt. The
StoreEOI operation has less latency and improves interrupt handling
performance but it was deactivated during the POWER9 DD2.0 timeframe
because of ordering issues. We use the LoadEOI today but we plan to
reactivate StoreEOI in future architectures.

There is usually no need to enforce ordering between ESB load and
store operations as they should lead to the same result. E.g. a store
trigger and a load EOI can be executed in any order. Assuming the
interrupt state is PQ=10, a store trigger followed by a load EOI will
return a Q bit. In the reverse order, it will create a new interrupt
trigger from HW. In both cases, the handler processing interrupts is
notified.

In some cases, the XIVE_ESB_SET_PQ_10 load operation is used to
disable temporarily the interrupt source (mask/unmask). When the
source is reenabled, the OS can detect if interrupts were received
while the source was disabled and reinject them. This process needs
special care when StoreEOI is activated. The ESB load and store
operations should be correctly ordered because a XIVE_ESB_STORE_EOI
operation could leave the source enabled if it has not completed
before the loads.

For those cases, we enforce Load-after-Store ordering with a special
load operation offset. To avoid performance impact, this ordering is
only enforced when really needed, that is when interrupt sources are
temporarily disabled with the XIVE_ESB_SET_PQ_10 load. It should not
be needed for other loads.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200220081506.31209-1-clg@kaod.org
2020-05-07 22:58:31 +10:00
Aneesh Kumar K.V
75358ea359 powerpc/mm/book3s64: Fix MADV_DONTNEED and parallel page fault race
MADV_DONTNEED holds mmap_sem in read mode and that implies a
parallel page fault is possible and the kernel can end up with a level 1 PTE
entry (THP entry) converted to a level 0 PTE entry without flushing
the THP TLB entry.

Most architectures including POWER have issues with kernel instantiating a level
0 PTE entry while holding level 1 TLB entries.

The code sequence I am looking at is

down_read(mmap_sem)                         down_read(mmap_sem)

zap_pmd_range()
 zap_huge_pmd()
  pmd lock held
  pmd_cleared
  table details added to mmu_gather
  pmd_unlock()
                                         insert a level 0 PTE entry()

tlb_finish_mmu().

Fix this by forcing a tlb flush before releasing pmd lock if this is
not a fullmm invalidate. We can safely skip this invalidate for
task exit case (fullmm invalidate) because in that case we are sure
there can be no parallel fault handlers.

This do change the Qemu guest RAM del/unplug time as below

128 core, 496GB guest:

Without patch:
munmap start: timer = 196449 ms, PID=6681
munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms

With patch:
munmap start: timer = 196345 ms, PID=6879
munmap finish: timer = 196714 ms, PID=6879 - delta = 369ms

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-23-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:16 +10:00
Aneesh Kumar K.V
e21dfbf013 powerpc/mm/book3s64: Avoid sending IPI on clearing PMD
Now that all the lockless page table walk is careful w.r.t the PTE
address returned, we can now revert
commit: 13bd817bb8 ("powerpc/thp: Serialize pmd clear against a linux page table walk.")

We also drop the equivalent IPI from other pte updates routines. We still keep
IPI in hash pmdp collapse and that is to take care of parallel hash page table
insert. The radix pmdp collapse flush can possibly be removed once I am sure
generic code doesn't have the any expectations around parallel gup walk.

This speeds up Qemu guest RAM del/unplug time as below

128 core, 496GB guest:

Without patch:
munmap start: timer = 13162 ms, PID=7684
munmap finish: timer = 95312 ms, PID=7684 - delta = 82150 ms

With patch:
munmap start: timer = 196449 ms, PID=6681
munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-21-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:16 +10:00
Aneesh Kumar K.V
0e11df9649 powerpc/kvm/book3s: Use pte_present instead of opencoding _PAGE_PRESENT check
This adds _PAGE_PTE check and makes sure we validate the pte value returned via
find_kvm_host_pte.

NOTE: this also considers _PAGE_INVALID to the software valid bit.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-20-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:16 +10:00
Aneesh Kumar K.V
9fd4236faa powerpc/kvm/book3s: Use find_kvm_host_pte in kvmppc_get_hpa
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-19-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:16 +10:00
Aneesh Kumar K.V
bda3deaa6f powerpc/kvm/book3s: use find_kvm_host_pte in kvmppc_book3s_instantiate_page
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-18-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:16 +10:00
Aneesh Kumar K.V
3ff8df1430 powerpc/kvm/book3s: Avoid using rmap to protect parallel page table update.
We now depend on kvm->mmu_lock

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-17-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
7769a3394b powerpc/kvm/book3s: use find_kvm_host_pte in pute_tce functions
Current code just hold rmap lock to ensure parallel page table update is
prevented. That is not sufficient. The kernel should also check whether
a mmu_notifer callback was running in parallel.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-16-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
e3d8ed5518 powerpc/kvm/book3s: Use find_kvm_host_pte in h_enter
Since kvmppc_do_h_enter can get called in realmode use low level
arch_spin_lock which is safe to be called in realmode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-15-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
9781e759b3 powerpc/kvm/book3s: Use find_kvm_host_pte in page fault handler
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-14-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
35528876a9 powerpc/kvm/book3s: Add helper for host page table walk
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-13-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
6cdf30375f powerpc/kvm/book3s: Use kvm helpers to walk shadow or secondary table
update kvmppc_hv_handle_set_rc to use find_kvm_nested_guest_pte and
find_kvm_secondary_pte

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-12-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
dc891849e0 powerpc/kvm/nested: Add helper to walk nested shadow linux page table.
The locking rules for walking nested shadow linux page table is different from process
scoped table. Hence add a helper for nested page table walk and also
add check whether we are holding the right locks.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-11-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
4b99412ed6 powerpc/kvm/book3s: Add helper to walk partition scoped linux page table.
The locking rules for walking partition scoped table is different from process
scoped table. Hence add a helper for secondary linux page table walk and also
add check whether we are holding the right locks.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-10-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:15 +10:00
Aneesh Kumar K.V
87013f9c60 powerpc/kvm/book3s: switch from raw_spin_*lock to arch_spin_lock.
These functions can get called in realmode. Hence use low level
arch_spin_lock which is safe to be called in realmode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-9-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
15759cb054 powerpc/perf/callchain: Use __get_user_pages_fast in read_user_stack_slow
read_user_stack_slow is called with interrupts soft disabled and it copies contents
from the page which we find mapped to a specific address. To convert
userspace address to pfn, the kernel now uses lockless page table walk.

The kernel needs to make sure the pfn value read remains stable and is not released
and reused for another process while the contents are read from the page. This
can only be achieved by holding a page reference.

One of the first approaches I tried was to check the pte value after the kernel
copies the contents from the page. But as shown below we can still get it wrong

CPU0                           CPU1
pte = READ_ONCE(*ptep);
                               pte_clear(pte);
                               put_page(page);
                               page = alloc_page();
                               memcpy(page_address(page), "secret password", nr);
memcpy(buf, kaddr + offset, nb);
                               put_page(page);
                               handle_mm_fault()
                               page = alloc_page();
                               set_pte(pte, page);
if (pte_val(pte) != pte_val(*ptep))

Hence switch to __get_user_pages_fast.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-8-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
0da81b658b powerpc/mce: Don't reload pte val in addr_to_pfn
A lockless page table walk should be safe against parallel THP collapse, THP
split and madvise(MADV_DONTNEED)/parallel fault. This patch makes sure kernel
won't reload the pteval when checking for different conditions. The patch also added
a check for pte_present to make sure the kernel is indeed operating
on a PTE and not a pointer to level 0 table page.

The pfn value we find here can be different from the actual pfn on which
machine check happened. This can happen if we raced with a parallel update
of the page table. In such a scenario we end up isolating a wrong pfn. But that
doesn't have any other side effect.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-7-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
2f92447f9f powerpc/book3s64/hash: Use the pte_t address from the caller
Don't fetch the pte value using lockless page table walk. Instead use the value from the
caller. hash_preload is called with ptl lock held. So it is safe to use the
pte_t address directly.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-6-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
7900757ce1 powerpc/hash64: Restrict page table lookup using init_mm with __flush_hash_table_range
This is only used with init_mm currently. Walking init_mm is much simpler
because we don't need to handle concurrent page table like other mm_context

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-5-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
ec4abf1e70 powerpc/mm/hash64: use _PAGE_PTE when checking for pte_present
This makes the pte_present check stricter by checking for additional _PAGE_PTE
bit. A level 1 pte pointer (THP pte) can be switched to a pointer to level 0 pte
page table page by following two operations.

1) THP split.
2) madvise(MADV_DONTNEED) in parallel to page fault.

A lockless page table walk need to make sure we can handle such changes
gracefully.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-4-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
c46241a370 powerpc/pkeys: Check vma before returning key fault error to the user
If multiple threads in userspace keep changing the protection keys
mapping a range, there can be a scenario where kernel takes a key fault
but the pkey value found in the siginfo struct is a permissive one.

This can confuse the userspace as shown in the below test case.

/* use this to control the number of test iterations */

static void pkeyreg_set(int pkey, unsigned long rights)
{
	unsigned long reg, shift;

	shift = (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
	asm volatile("mfspr	%0, 0xd" : "=r"(reg));
	reg &= ~(((unsigned long) PKEY_BITS_MASK) << shift);
	reg |= (rights & PKEY_BITS_MASK) << shift;
	asm volatile("mtspr	0xd, %0" : : "r"(reg));
}

static unsigned long pkeyreg_get(void)
{
	unsigned long reg;

	asm volatile("mfspr	%0, 0xd" : "=r"(reg));
	return reg;
}

static int sys_pkey_mprotect(void *addr, size_t len, int prot, int pkey)
{
	return syscall(SYS_pkey_mprotect, addr, len, prot, pkey);
}

static int sys_pkey_alloc(unsigned long flags, unsigned long access_rights)
{
	return syscall(SYS_pkey_alloc, flags, access_rights);
}

static int sys_pkey_free(int pkey)
{
	return syscall(SYS_pkey_free, pkey);
}

static int faulting_pkey;
static int permissive_pkey;
static pthread_barrier_t pkey_set_barrier;
static pthread_barrier_t mprotect_barrier;

static void pkey_handle_fault(int signum, siginfo_t *sinfo, void *ctx)
{
	unsigned long pkeyreg;

	/* FIXME: printf is not signal-safe but for the current purpose,
	          it gets the job done. */
	printf("pkey: exp = %d, got = %d\n", faulting_pkey, sinfo->si_pkey);
	fflush(stdout);

	assert(sinfo->si_code == SEGV_PKUERR);
	assert(sinfo->si_pkey == faulting_pkey);

	/* clear pkey permissions to let the faulting instruction continue */
	pkeyreg_set(faulting_pkey, 0x0);
}

static void *do_mprotect_fault(void *p)
{
	unsigned long rights, pkeyreg, pgsize;
	unsigned int i;
	void *region;
	int pkey;

	srand(time(NULL));
	pgsize = sysconf(_SC_PAGESIZE);
	rights = PKEY_DISABLE_WRITE;
	region = p;

	/* allocate key, no permissions */
	assert((pkey = sys_pkey_alloc(0, PKEY_DISABLE_ACCESS)) > 0);
	pkeyreg_set(4, 0x0);

	/* cache the pkey here as the faulting pkey for future reference
	   in the signal handler */
	faulting_pkey = pkey;
	printf("%s: faulting pkey = %d\n", __func__, faulting_pkey);

	/* try to allocate, mprotect and free pkeys repeatedly */
	for (i = 0; i < NUM_ITERATIONS; i++) {
		/* sync up with the other thread here */
		pthread_barrier_wait(&pkey_set_barrier);

		/* make sure that the pkey used by the non-faulting thread
		   is made permissive for this thread's context too so that
		   no faults are triggered because it still might have been
		   set to a restrictive value */
//		pkeyreg_set(permissive_pkey, 0x0);

		/* sync up with the other thread here */
		pthread_barrier_wait(&mprotect_barrier);

		/* perform mprotect */
		assert(!sys_pkey_mprotect(region, pgsize, PROT_READ | PROT_WRITE, pkey));

		/* choose a random byte from the protected region and
		   attempt to write to it, this will generate a fault */
		*((char *) region + (rand() % pgsize)) = rand();

		/* restore pkey permissions as the signal handler may have
		   cleared the bit out for the sake of continuing */
		pkeyreg_set(pkey, PKEY_DISABLE_WRITE);
	}

	/* free pkey */
	sys_pkey_free(pkey);

	return NULL;
}

static void *do_mprotect_nofault(void *p)
{
	unsigned long pgsize;
	unsigned int i, j;
	void *region;
	int pkey;

	pgsize = sysconf(_SC_PAGESIZE);
	region = p;

	/* try to allocate, mprotect and free pkeys repeatedly */
	for (i = 0; i < NUM_ITERATIONS; i++) {
		/* allocate pkey, all permissions */
		assert((pkey = sys_pkey_alloc(0, 0)) > 0);
		permissive_pkey = pkey;

		/* sync up with the other thread here */
		pthread_barrier_wait(&pkey_set_barrier);
		pthread_barrier_wait(&mprotect_barrier);

		/* perform mprotect on the common page, no faults will
		   be triggered as this is most permissive */
		assert(!sys_pkey_mprotect(region, pgsize, PROT_READ | PROT_WRITE, pkey));

		/* free pkey */
		assert(!sys_pkey_free(pkey));
	}

	return NULL;
}

int main(int argc, char **argv)
{
	pthread_t fault_thread, nofault_thread;
	unsigned long pgsize;
	struct sigaction act;
	pthread_attr_t attr;
	cpu_set_t fault_cpuset, nofault_cpuset;
	unsigned int i;
	void *region;

	/* allocate memory region to protect */
	pgsize = sysconf(_SC_PAGESIZE);
	assert(region = memalign(pgsize, pgsize));

	CPU_ZERO(&fault_cpuset);
	CPU_SET(0, &fault_cpuset);
	CPU_ZERO(&nofault_cpuset);
	CPU_SET(8, &nofault_cpuset);
	assert(!pthread_attr_init(&attr));

	/* setup sigsegv signal handler */
	act.sa_handler = 0;
	act.sa_sigaction = pkey_handle_fault;
	assert(!sigprocmask(SIG_SETMASK, 0, &act.sa_mask));
	act.sa_flags = SA_SIGINFO;
	act.sa_restorer = 0;
	assert(!sigaction(SIGSEGV, &act, NULL));

	/* setup barrier for the two threads */
	pthread_barrier_init(&pkey_set_barrier, NULL, 2);
	pthread_barrier_init(&mprotect_barrier, NULL, 2);

	/* setup and start threads */
	assert(!pthread_create(&fault_thread, &attr, &do_mprotect_fault, region));
	assert(!pthread_setaffinity_np(fault_thread, sizeof(cpu_set_t), &fault_cpuset));
	assert(!pthread_create(&nofault_thread, &attr, &do_mprotect_nofault, region));
	assert(!pthread_setaffinity_np(nofault_thread, sizeof(cpu_set_t), &nofault_cpuset));

	/* cleanup */
	assert(!pthread_attr_destroy(&attr));
	assert(!pthread_join(fault_thread, NULL));
	assert(!pthread_join(nofault_thread, NULL));
	assert(!pthread_barrier_destroy(&pkey_set_barrier));
	assert(!pthread_barrier_destroy(&mprotect_barrier));
	free(region);

	puts("PASS");

	return EXIT_SUCCESS;
}

The above test can result the below failure without this patch.

pkey: exp = 3, got = 3
pkey: exp = 3, got = 4
a.out: pkey-siginfo-race.c💯 pkey_handle_fault: Assertion `sinfo->si_pkey == faulting_pkey' failed.
Aborted

Check for vma access before considering this a key fault. If vma pkey allow
access retry the acess again.

Test case is written by Sandipan Das <sandipan@linux.ibm.com> hence added SOB
from him.

Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-3-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
Aneesh Kumar K.V
fe4a6856cb powerpc/pkeys: Avoid using lockless page table walk
Fetch pkey from vma instead of linux page table. Also document the fact that in
some cases the pkey returned in siginfo won't be the same as the one we took
keyfault on. Even with linux page table walk, we can end up in a similar scenario.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-2-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:13 +10:00
Aneesh Kumar K.V
93a98695f2 mm: change pmdp_huge_get_and_clear_full take vm_area_struct as arg
We will use this in later patch to do tlb flush when clearing pmd entries.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-22-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:13 +10:00
Michael Ellerman
f2b8d76dc6 PPC KVM fix for 5.7
- Fix a regression introduced in the last merge window, which results
   in guests in HPT mode dying randomly.
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Merge tag 'kvm-ppc-fixes-5.7-1' into topic/ppc-kvm

This brings in a fix from the kvm-ppc tree that was merged to mainline
after rc2, and so isn't in the base of our topic branch. We'd like it
in the topic branch because it interacts with patches we plan to carry
in this branch.
2020-05-05 21:16:47 +10:00
Paul Mackerras
ae49dedaa9 KVM: PPC: Book3S HV: Handle non-present PTEs in page fault functions
Since cd758a9b57 "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT
page fault handler", it's been possible in fairly rare circumstances to
load a non-present PTE in kvmppc_book3s_hv_page_fault() when running a
guest on a POWER8 host.

Because that case wasn't checked for, we could misinterpret the non-present
PTE as being a cache-inhibited PTE.  That could mismatch with the
corresponding hash PTE, which would cause the function to fail with -EFAULT
a little further down.  That would propagate up to the KVM_RUN ioctl()
generally causing the KVM userspace (usually qemu) to fall over.

This addresses the problem by catching that case and returning to the guest
instead.

For completeness, this fixes the radix page fault handler in the same
way.  For radix this didn't cause any obvious misbehaviour, because we
ended up putting the non-present PTE into the guest's partition-scoped
page tables, leading immediately to another hypervisor data/instruction
storage interrupt, which would go through the page fault path again
and fix things up.

Fixes: cd758a9b57 "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT page fault handler"
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1820402
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2020-04-21 09:23:41 +10:00
Linus Torvalds
ae83d0b416 Linux 5.7-rc2 2020-04-19 14:35:30 -07:00
Brian Geffon
dadbd85f2a mm: Fix MREMAP_DONTUNMAP accounting on VMA merge
When remapping a mapping where a portion of a VMA is remapped
into another portion of the VMA it can cause the VMA to become
split. During the copy_vma operation the VMA can actually
be remerged if it's an anonymous VMA whose pages have not yet
been faulted. This isn't normally a problem because at the end
of the remap the original portion is unmapped causing it to
become split again.

However, MREMAP_DONTUNMAP leaves that original portion in place which
means that the VMA which was split and then remerged is not actually
split at the end of the mremap. This patch fixes a bug where
we don't detect that the VMAs got remerged and we end up
putting back VM_ACCOUNT on the next mapping which is completely
unreleated. When that next mapping is unmapped it results in
incorrectly unaccounting for the memory which was never accounted,
and eventually we will underflow on the memory comittment.

There is also another issue which is similar, we're currently
accouting for the number of pages in the new_vma but that's wrong.
We need to account for the length of the remap operation as that's
all that is being added. If there was a mapping already at that
location its comittment would have been adjusted as part of
the munmap at the start of the mremap.

A really simple repro can be seen in:
https://gist.github.com/bgaff/e101ce99da7d9a8c60acc641d07f312c

Fixes: e346b38130 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-19 14:07:10 -07:00
Linus Torvalds
86cc339856 Two build fixes for a couple clk drivers and a fix for the Unisoc serial
clk where we want to keep it on for earlycon.
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Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux

Pull clk fixes from Stephen Boyd:
 "Two build fixes for a couple clk drivers and a fix for the Unisoc
  serial clk where we want to keep it on for earlycon"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: sprd: don't gate uart console clock
  clk: mmp2: fix link error without mmp2
  clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo
2020-04-19 13:59:06 -07:00
Linus Torvalds
0fe5f9ca22 A set of fixes for x86 and objtool:
objtool:
 
   - Ignore the double UD2 which is emitted in BUG() when CONFIG_UBSAN_TRAP
     is enabled.
 
   - Support clang non-section symbols in objtool ORC dump
 
   - Fix switch table detection in .text.unlikely
 
   - Make the BP scratch register warning more robust.
 
  x86:
 
   - Increase microcode maximum patch size for AMD to cope with new CPUs
     which have a larger patch size.
 
   - Fix a crash in the resource control filesystem when the removal of the
     default resource group is attempted.
 
   - Preserve Code and Data Prioritization enabled state accross CPU
     hotplug.
 
   - Update split lock cpu matching to use the new X86_MATCH macros.
 
   - Change the split lock enumeration as Intel finaly decided that the
     IA32_CORE_CAPABILITIES bits are not architectural contrary to what
     the SDM claims. !@#%$^!
 
   - Add Tremont CPU models to the split lock detection cpu match.
 
   - Add a missing static attribute to make sparse happy.
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Merge tag 'x86-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 and objtool fixes from Thomas Gleixner:
 "A set of fixes for x86 and objtool:

  objtool:

   - Ignore the double UD2 which is emitted in BUG() when
     CONFIG_UBSAN_TRAP is enabled.

   - Support clang non-section symbols in objtool ORC dump

   - Fix switch table detection in .text.unlikely

   - Make the BP scratch register warning more robust.

  x86:

   - Increase microcode maximum patch size for AMD to cope with new CPUs
     which have a larger patch size.

   - Fix a crash in the resource control filesystem when the removal of
     the default resource group is attempted.

   - Preserve Code and Data Prioritization enabled state accross CPU
     hotplug.

   - Update split lock cpu matching to use the new X86_MATCH macros.

   - Change the split lock enumeration as Intel finaly decided that the
     IA32_CORE_CAPABILITIES bits are not architectural contrary to what
     the SDM claims. !@#%$^!

   - Add Tremont CPU models to the split lock detection cpu match.

   - Add a missing static attribute to make sparse happy"

* tag 'x86-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/split_lock: Add Tremont family CPU models
  x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural
  x86/resctrl: Preserve CDP enable over CPU hotplug
  x86/resctrl: Fix invalid attempt at removing the default resource group
  x86/split_lock: Update to use X86_MATCH_INTEL_FAM6_MODEL()
  x86/umip: Make umip_insns static
  x86/microcode/AMD: Increase microcode PATCH_MAX_SIZE
  objtool: Make BP scratch register warning more robust
  objtool: Fix switch table detection in .text.unlikely
  objtool: Support Clang non-section symbols in ORC generation
  objtool: Support Clang non-section symbols in ORC dump
  objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings
2020-04-19 11:58:32 -07:00
Linus Torvalds
3e0dea5768 An update for the proc interface of time namespaces: Use symbolic names
instead of clockid numbers. The usability nuisance of numbers was noticed
 by Michael when polishing the man page.
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Merge tag 'timers-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull time namespace fix from Thomas Gleixner:
 "An update for the proc interface of time namespaces: Use symbolic
  names instead of clockid numbers. The usability nuisance of numbers
  was noticed by Michael when polishing the man page"

* tag 'timers-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets
2020-04-19 11:46:21 -07:00
Linus Torvalds
b7374586eb Perf updates and fixes:
- Fix the header line of perf stat output for '--metric-only --per-socket'
 
  - Fix the python build with clang
 
  - The usual tools UAPI header synchronization
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Merge tag 'perf-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf tooling fixes and updates from Thomas Gleixner:

 - Fix the header line of perf stat output for '--metric-only --per-socket'

 - Fix the python build with clang

 - The usual tools UAPI header synchronization

* tag 'perf-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools headers: Synchronize linux/bits.h with the kernel sources
  tools headers: Adopt verbatim copy of compiletime_assert() from kernel sources
  tools headers: Update x86's syscall_64.tbl with the kernel sources
  tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
  tools headers UAPI: Update tools's copy of drm.h headers
  tools headers kvm: Sync linux/kvm.h with the kernel sources
  tools headers UAPI: Sync linux/fscrypt.h with the kernel sources
  tools include UAPI: Sync linux/vhost.h with the kernel sources
  tools arch x86: Sync asm/cpufeatures.h with the kernel sources
  tools headers UAPI: Sync linux/mman.h with the kernel
  tools headers UAPI: Sync sched.h with the kernel
  tools headers: Update linux/vdso.h and grab a copy of vdso/const.h
  perf stat: Fix no metric header if --per-socket and --metric-only set
  perf python: Check if clang supports -fno-semantic-interposition
  tools arch x86: Sync the msr-index.h copy with the kernel sources
2020-04-19 11:28:01 -07:00
Linus Torvalds
80ade29e1e A set of fixes/updates for the interrupt subsystem:
- Remove setup_irq() and remove_irq(). All users have been converted so
    remove them before new users surface.
 
  - A set of bugfixes for various interrupt chip drivers
 
  - Add a few missing static attributes to address sparse warnings.
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Merge tag 'irq-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq fixes from Thomas Gleixner:
 "A set of fixes/updates for the interrupt subsystem:

   - Remove setup_irq() and remove_irq(). All users have been converted
     so remove them before new users surface.

   - A set of bugfixes for various interrupt chip drivers

   - Add a few missing static attributes to address sparse warnings"

* tag 'irq-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/irq-bcm7038-l1: Make bcm7038_l1_of_init() static
  irqchip/irq-mvebu-icu: Make legacy_bindings static
  irqchip/meson-gpio: Fix HARDIRQ-safe -> HARDIRQ-unsafe lock order
  irqchip/sifive-plic: Fix maximum priority threshold value
  irqchip/ti-sci-inta: Fix processing of masked irqs
  irqchip/mbigen: Free msi_desc on device teardown
  irqchip/gic-v4.1: Update effective affinity of virtual SGIs
  irqchip/gic-v4.1: Add support for VPENDBASER's Dirty+Valid signaling
  genirq: Remove setup_irq() and remove_irq()
2020-04-19 11:23:33 -07:00
Linus Torvalds
08dd387277 Two fixes for the scheduler:
- Work around an uninitializaed variable warning where GCC can't figure it
    out.
 
  - Allow 'isolcpus=' to skip unknown subparameters so that older kernels
    work with the commandline of a newer kernel. Improve the error output
    while at it.
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Merge tag 'sched-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Thomas Gleixner:
 "Two fixes for the scheduler:

   - Work around an uninitialized variable warning where GCC can't
     figure it out.

   - Allow 'isolcpus=' to skip unknown subparameters so that older
     kernels work with the commandline of a newer kernel. Improve the
     error output while at it"

* tag 'sched-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/vtime: Work around an unitialized variable warning
  sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters
2020-04-19 11:18:20 -07:00
Linus Torvalds
5e7de58127 A single bugfix for RCU to prevent taking a lock in NMI context.
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Merge tag 'core-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU fix from Thomas Gleixner:
 "A single bugfix for RCU to prevent taking a lock in NMI context"

* tag 'core-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Don't acquire lock in NMI handler in rcu_nmi_enter_common()
2020-04-19 11:16:00 -07:00
Linus Torvalds
439f1da923 Miscellaneous bug fixes and cleanups for ext4, including a fix for
generic/388 in data=journal mode, removing some BUG_ON's, and cleaning
 up some compiler warnings.
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Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Miscellaneous bug fixes and cleanups for ext4, including a fix for
  generic/388 in data=journal mode, removing some BUG_ON's, and cleaning
  up some compiler warnings"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: convert BUG_ON's to WARN_ON's in mballoc.c
  ext4: increase wait time needed before reuse of deleted inode numbers
  ext4: remove set but not used variable 'es' in ext4_jbd2.c
  ext4: remove set but not used variable 'es'
  ext4: do not zeroout extents beyond i_disksize
  ext4: fix return-value types in several function comments
  ext4: use non-movable memory for superblock readahead
  ext4: use matching invalidatepage in ext4_writepage
2020-04-19 11:05:15 -07:00
Linus Torvalds
aee0314bc3 Three small smb3 fixes: two debug related, and one fixing a performance problem with 64K pages
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Merge tag '5.7-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:
 "Three small smb3 fixes: two debug related (helping network tracing for
  SMB2 mounts, and the other removing an unintended debug line on
  signing failures), and one fixing a performance problem with 64K
  pages"

* tag '5.7-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: remove overly noisy debug line in signing errors
  cifs: improve read performance for page size 64KB & cache=strict & vers=2.1+
  cifs: dump the session id and keys also for SMB2 sessions
2020-04-19 11:00:27 -07:00
Linus Torvalds
1340283741 flexible-array member convertion patches for 5.7-rc2
Hi Linus,
 
 Please, pull the following patches that replace zero-length arrays with
 flexible-array members.
 
 The current codebase makes use of the zero-length array language
 extension to the C90 standard, but the preferred mechanism to declare
 variable-length types such as these ones is a flexible array member[1][2],
 introduced in C99:
 
 struct foo {
         int stuff;
         struct boo array[];
 };
 
 By making use of the mechanism above, we will get a compiler warning
 in case the flexible array does not occur last in the structure, which
 will help us prevent some kind of undefined behavior bugs from being
 inadvertently introduced[3] to the codebase from now on.
 
 Also, notice that, dynamic memory allocations won't be affected by
 this change:
 
 "Flexible array members have incomplete type, and so the sizeof operator
 may not be applied. As a quirk of the original implementation of
 zero-length arrays, sizeof evaluates to zero."[1]
 
 sizeof(flexible-array-member) triggers a warning because flexible array
 members have incomplete type[1]. There are some instances of code in
 which the sizeof operator is being incorrectly/erroneously applied to
 zero-length arrays and the result is zero. Such instances may be hiding
 some bugs. So, this work (flexible-array member convertions) will also
 help to get completely rid of those sorts of issues.
 
 Notice that all of these patches have been baking in linux-next for
 quite a while now and, 238 more of these patches have already been
 merged into 5.7-rc1.
 
 There are a couple hundred more of these issues waiting to be addressed
 in the whole codebase.
 
 [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
 [2] https://github.com/KSPP/linux/issues/21
 [3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
 
 Thanks
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Merge tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull flexible-array member conversion from Gustavo Silva:
 "The current codebase makes use of the zero-length array language
  extension to the C90 standard, but the preferred mechanism to declare
  variable-length types such as these ones is a flexible array
  member[1][2], introduced in C99:

    struct foo {
        int stuff;
        struct boo array[];
    };

  By making use of the mechanism above, we will get a compiler warning
  in case the flexible array does not occur last in the structure, which
  will help us prevent some kind of undefined behavior bugs from being
  inadvertently introduced[3] to the codebase from now on.

  Also, notice that, dynamic memory allocations won't be affected by
  this change:

   "Flexible array members have incomplete type, and so the sizeof
    operator may not be applied. As a quirk of the original
    implementation of zero-length arrays, sizeof evaluates to zero."[1]

  sizeof(flexible-array-member) triggers a warning because flexible
  array members have incomplete type[1]. There are some instances of
  code in which the sizeof operator is being incorrectly/erroneously
  applied to zero-length arrays and the result is zero. Such instances
  may be hiding some bugs. So, this work (flexible-array member
  convertions) will also help to get completely rid of those sorts of
  issues.

  Notice that all of these patches have been baking in linux-next for
  quite a while now and, 238 more of these patches have already been
  merged into 5.7-rc1.

  There are a couple hundred more of these issues waiting to be
  addressed in the whole codebase"

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

* tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (28 commits)
  xattr.h: Replace zero-length array with flexible-array member
  uapi: linux: fiemap.h: Replace zero-length array with flexible-array member
  uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member
  tpm_eventlog.h: Replace zero-length array with flexible-array member
  ti_wilink_st.h: Replace zero-length array with flexible-array member
  swap.h: Replace zero-length array with flexible-array member
  skbuff.h: Replace zero-length array with flexible-array member
  sched: topology.h: Replace zero-length array with flexible-array member
  rslib.h: Replace zero-length array with flexible-array member
  rio.h: Replace zero-length array with flexible-array member
  posix_acl.h: Replace zero-length array with flexible-array member
  platform_data: wilco-ec.h: Replace zero-length array with flexible-array member
  memcontrol.h: Replace zero-length array with flexible-array member
  list_lru.h: Replace zero-length array with flexible-array member
  lib: cpu_rmap: Replace zero-length array with flexible-array member
  irq.h: Replace zero-length array with flexible-array member
  ihex.h: Replace zero-length array with flexible-array member
  igmp.h: Replace zero-length array with flexible-array member
  genalloc.h: Replace zero-length array with flexible-array member
  ethtool.h: Replace zero-length array with flexible-array member
  ...
2020-04-19 10:34:30 -07:00
Linus Torvalds
50cc09c189 SCSI fixes on 20200418
Seven fixes; three in target, one on a sg error leg, two in qla2xxx
 fixing warnings introduced in the last merge window and updating
 MAINTAINERS and one in hisi_sas fixing a problem introduced by libata.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "Seven fixes: three in target, one on a sg error leg, two in qla2xxx
  fixing warnings introduced in the last merge window and updating
  MAINTAINERS and one in hisi_sas fixing a problem introduced by libata"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sg: add sg_remove_request in sg_common_write
  scsi: target: tcmu: reset_ring should reset TCMU_DEV_BIT_BROKEN
  scsi: target: fix PR IN / READ FULL STATUS for FC
  scsi: target: Write NULL to *port_nexus_ptr if no ISID
  scsi: MAINTAINERS: Update qla2xxx FC-SCSI driver maintainer
  scsi: qla2xxx: Fix regression warnings
  scsi: hisi_sas: Fix build error without SATA_HOST
2020-04-18 14:03:12 -07:00
Gustavo A. R. Silva
43951585e1 xattr.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
6e88abb862 uapi: linux: fiemap.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
d6cdad8703 uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
06ccf63da5 tpm_eventlog.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
4ea19ecf32 ti_wilink_st.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
16c3380f8c swap.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
5c91aa1df0 skbuff.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
fe946db6ca sched: topology.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
9dd8bb5f8c rslib.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
a1c4b9247d rio.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Gustavo A. R. Silva
70f1451ec9 posix_acl.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:55 -05:00
Gustavo A. R. Silva
1223f3db71 platform_data: wilco-ec.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:55 -05:00