linux_dsm_epyc7002/arch/x86/kernel
Borislav Petkov dbe4058a6a x86/alternatives: Fix ALTERNATIVE_2 padding generation properly
Quentin caught a corner case with the generation of instruction
padding in the ALTERNATIVE_2 macro: if len(orig_insn) <
len(alt1) < len(alt2), then not enough padding gets added and
that is not good(tm) as we could overwrite the beginning of the
next instruction.

Luckily, at the time of this writing, we don't have
ALTERNATIVE_2() invocations which have that problem and even if
we did, a simple fix would be to prepend the instructions with
enough prefixes so that that corner case doesn't happen.

However, best it would be if we fixed it properly. See below for
a simple, abstracted example of what we're doing.

So what we ended up doing is, we compute the

	max(len(alt1), len(alt2)) - len(orig_insn)

and feed that value to the .skip gas directive. The max() cannot
have conditionals due to gas limitations, thus the fancy integer
math.

With this patch, all ALTERNATIVE_2 sites get padded correctly;
generating obscure test cases pass too:

  #define alt_max_short(a, b)    ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))

  #define gen_skip(orig, alt1, alt2, marker)	\
  	.skip -((alt_max_short(alt1, alt2) - (orig)) > 0) * \
  		(alt_max_short(alt1, alt2) - (orig)),marker

  	.pushsection .text, "ax"
  .globl main
  main:
  	gen_skip(1, 2, 4, 0x09)
  	gen_skip(4, 1, 2, 0x10)
  	...
  	.popsection

Thanks to Quentin for catching it and double-checking the fix!

Reported-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150404133443.GE21152@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-04 15:58:23 +02:00
..
acpi x86/platform, acpi: Bypass legacy PIC and PIT in ACPI hardware reduced mode 2015-03-12 12:07:13 +01:00
apic x86/apic/numachip: Fix sibling map with NumaChip 2015-03-12 16:58:59 +01:00
cpu x86/asm/entry/64: Use a define for an invalid segment selector 2015-04-03 15:29:13 +02:00
kprobes x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
.gitignore
alternative.c x86/alternatives: Fix ALTERNATIVE_2 padding generation properly 2015-04-04 15:58:23 +02:00
amd_gart_64.c
amd_nb.c x86, amd_nb: Add device IDs to NB tables for F15h M60h 2014-10-20 14:18:45 +02:00
apb_timer.c x86/platform: Remove unused function from apb_timer.c 2014-12-23 10:43:35 +01:00
aperture_64.c
apm_32.c cpuidle: Invert CPUIDLE_FLAG_TIME_VALID logic 2014-11-12 21:17:27 +01:00
asm-offsets_32.c x86/asm/entry/32: Document the 32-bit SYSENTER "emergency stack" better 2015-03-17 09:25:29 +01:00
asm-offsets_64.c x86/asm/entry/64/compat: Change the 32-bit sysenter code to use sp0 2015-03-06 08:32:58 +01:00
asm-offsets.c
audit_64.c x86: hook up execveat system call 2014-12-13 12:42:51 -08:00
bootflag.c
check.c
cpuid.c x86, cpuid: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:51 -07:00
crash_dump_32.c
crash_dump_64.c
crash.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
devicetree.c
doublefault.c
dumpstack_32.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
dumpstack_64.c x86_64, traps: Stop using IST for #SS 2014-11-23 13:56:19 -08:00
dumpstack.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
e820.c x86, e820: Clean up sanitize_e820_map() users 2015-01-23 16:14:27 +01:00
early_printk.c Specify PCI based UART for earlyprintk 2015-02-02 10:11:27 -08:00
early-quirks.c drm/i915/skl: Add the additional graphics stolen sizes 2014-09-24 14:47:39 +02:00
entry_32.S x86/asm/entry/32: Improve a TOP_OF_KERNEL_STACK_PADDING comment 2015-04-03 08:30:44 +02:00
entry_64.S x86/asm/entry/64: Fold the 'test_in_nmi' macro into its only user 2015-04-02 12:00:10 +02:00
espfix_64.c x86, espfix: Remove stale ptemask 2014-11-11 17:57:46 +01:00
ftrace.c module: remove mod arg from module_free, rename module_memfree(). 2015-01-20 11:38:33 +10:30
head32.c x86: Store a per-cpu shadow copy of CR4 2015-02-04 12:10:42 +01:00
head64.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-16 14:58:12 -08:00
head_32.S x86/asm/boot: Use already defined KEEP_SEGMENTS macro in head_{32,64}.S 2015-02-19 10:05:04 +01:00
head_64.S x86/asm: Optimize unnecessarily wide TEST instructions 2015-03-07 11:12:43 +01:00
head.c
hpet.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
hw_breakpoint.c perf/x86: Remove get_hbp_len and replace with bp_len 2014-12-03 15:14:30 +01:00
i386_ksyms_32.c
i387.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
i8237.c
i8253.c
i8259.c x86/irq: Fix XT-PIC-XT-PIC in /proc/interrupts 2014-10-28 12:01:08 +01:00
io_delay.c
ioport.c x86/asm/entry: Rename 'init_tss' to 'cpu_tss' 2015-03-06 08:32:58 +01:00
iosf_mbi.c x86/platform/intel/iosf: Add debugfs config option for IOSF 2014-09-19 13:08:43 +02:00
irq_32.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
irq_64.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
irq_work.c x86: Tell irq work about self IPI support 2014-09-13 18:38:29 +02:00
irq.c x86/irq: Check for valid irq descriptor in check_irq_vectors_for_cpu_disable() 2015-02-18 15:01:42 +01:00
irqinit.c x86, irq: Move local APIC related code from io_apic.c into vector.c 2014-12-16 14:08:16 +01:00
jump_label.c
kdebugfs.c
kexec-bzimage64.c kexec-bzimage64: fix sparse warnings 2014-10-14 02:18:21 +02:00
kgdb.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
ksysfs.c
kvm.c x86/spinlocks/paravirt: Fix memory corruption on unlock 2015-02-18 14:53:49 +01:00
kvmclock.c x86, kvm: Clear paravirt_enabled on KVM guests for espfix32's benefit 2014-12-10 12:49:39 +01:00
ldt.c
livepatch.c livepatch: kernel: add support for live patching 2014-12-22 15:40:49 +01:00
machine_kexec_32.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
machine_kexec_64.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
Makefile Linux 4.0-rc2 2015-03-04 06:35:43 +01:00
mcount_64.S ftrace/fgraph/x86: Have prepare_ftrace_return() take ip as first parameter 2014-12-01 14:08:58 -05:00
mmconf-fam10h_64.c
module.c x86/mm/KASLR: Propagate KASLR status to kernel proper 2015-04-03 15:26:15 +02:00
mpparse.c x86, apic: Remove mps_oem_check callback 2014-07-31 08:05:42 -07:00
msr.c x86, msr: Use seek definitions instead of hard-coded values 2014-10-17 13:40:55 -07:00
nmi_selftest.c
nmi.c
paravirt_patch_32.c
paravirt_patch_64.c x86_64/entry/xen: Do not invoke espfix64 on Xen 2014-07-28 15:25:40 -07:00
paravirt-spinlocks.c
paravirt.c
pci-calgary_64.c
pci-dma.c
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c
pcspeaker.c
perf_regs.c x86/asm/entry/64: Save user RSP in pt_regs->sp on SYSCALL64 fastpath 2015-03-10 13:56:10 +01:00
pmc_atom.c x86: pmc_atom: Expose contents of PSS 2015-01-20 12:50:14 +01:00
probe_roms.c
process_32.c x86/asm/entry: Get rid of KERNEL_STACK_OFFSET 2015-03-24 19:42:38 +01:00
process_64.c x86/asm/entry: Get rid of KERNEL_STACK_OFFSET 2015-03-24 19:42:38 +01:00
process.c x86/asm/entry: Unify and fix initial thread_struct::sp0 values 2015-03-17 09:25:27 +01:00
ptrace.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
pvclock.c
quirks.c x86: HPET force enable for e6xx based systems 2014-09-15 17:53:35 -07:00
reboot_fixups_32.c
reboot.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
relocate_kernel_32.S x86/asm: Optimize unnecessarily wide TEST instructions 2015-03-07 11:12:43 +01:00
relocate_kernel_64.S x86/asm: Replace "MOVQ $imm, %reg" with MOVL 2015-04-01 13:17:39 +02:00
resource.c x86: don't exclude low BIOS area when allocating address space for non-PCI cards 2014-07-16 12:29:36 -06:00
rtc.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
setup_percpu.c x86: Convert a few more per-CPU items to read-mostly ones 2014-11-04 20:13:28 +01:00
setup.c x86/mm/KASLR: Propagate KASLR status to kernel proper 2015-04-03 15:26:15 +02:00
signal.c x86/asm/entry: Fix execve() and sigreturn() syscalls to always return via IRET 2015-03-23 08:52:46 +01:00
smp.c
smpboot.c x86/cpu: Factor out common CPU initialization code, fix 32-bit Xen PV guests 2015-04-02 12:06:41 +02:00
stacktrace.c
step.c
sys_x86_64.c
syscall_32.c x86/compat: Merge native and compat 32-bit syscall tables 2015-03-04 06:16:21 +01:00
syscall_64.c
sysfb_efi.c
sysfb_simplefb.c x86/simplefb: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:52 -07:00
sysfb.c x86/sysfb: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:52 -07:00
tboot.c
tce_64.c
test_nx.c
test_rodata.c
time.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
tls.c x86, tls: Interpret an all-zero struct user_desc as "no segment" 2015-01-22 21:45:07 +01:00
tls.h
topology.c
trace_clock.c
tracepoint.c
traps.c x86/asm/entry: Remove user_mode_ignore_vm86() 2015-03-31 11:45:19 +02:00
tsc_msr.c
tsc_sync.c
tsc.c x86/tsc: Change Fast TSC calibration failed from error to info 2015-01-23 10:53:52 +01:00
uprobes.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
verify_cpu.S
vm86_32.c x86/asm/entry: Rename 'init_tss' to 'cpu_tss' 2015-03-06 08:32:58 +01:00
vmlinux.lds.S x86-64: Use RIP-relative addressing for most per-CPU accesses 2014-11-04 20:43:14 +01:00
vsmp_64.c x86/apic/vsmp: Make is_vsmp_box() static 2014-08-01 15:09:45 -07:00
vsyscall_64.c x86_64/vsyscall: Restore orig_ax after vsyscall seccomp 2014-11-10 10:46:35 +01:00
vsyscall_emu_64.S
vsyscall_gtod.c timekeeping: Create struct tk_read_base and use it in struct timekeeper 2014-07-23 15:01:53 -07:00
vsyscall_trace.h
x86_init.c Revert "PCI: Add x86_msi.msi_mask_irq() and msix_mask_irq()" 2014-11-11 15:14:30 -07:00
x8664_ksyms_64.c x86_64: kasan: add interceptors for memset/memmove/memcpy functions 2015-02-13 21:21:41 -08:00
xsave.c x86/fpu: Avoid math_state_restore() without used_math() in __restore_xstate_sig() 2015-03-13 12:44:28 +01:00