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 conversions) will also
help to get completely rid of those sorts of issues.
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 <gustavoars@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Misuse of CONFIG_* in UAPI headers should result in an error. These config
options can be set in userspace by the user application which includes
these headers to control the APIs and structures being used in a kernel
which supports multiple targets.
Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Merge {CLEAN,MRPROPER,DISTCLEAN}_DIRS into {CLEAN,MRPROPER,DISTCLEAN}_FILES
because the difference is just the -r option passed to the 'rm' command.
Do likewise as commit 1634f2bfdb ("kbuild: remove clean-dirs syntax").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
If include/generated/autoconf.h is accidentally lost somehow,
there is no clear way to fix it. Make it self-healing.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.
Add the entry to samples/Makefile to put this into the build bot
coverage.
I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.
Add the entry to samples/Makefile to put this into the build bot
coverage.
I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.
Add the entry to samples/Makefile to put this into the build bot
coverage.
I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.
I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.
I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
These userspace programs include UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample programs should be built for
the target as well. Kbuild now supports 'userprogs' for that.
I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.
$(CC) can always compile cn_text.o since it is the kenrel-space code,
but building ucon requires libc.
I guarded it by:
always-$(CONFIG_CC_CAN_LINK) := $(userprogs)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.
I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.
Add the entry to samples/Makefile to put this into the build bot
coverage.
I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Fix warnings seen when building for 32-bit architecture.
Use "%xd" for arguments of type size_t to fix the warnings.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Kbuild now supports the syntax 'userprogs' to compile userspace
programs for the same architecture as the kernel.
Insert the section '5 Userspace Program support' to explain it.
I copy-pasted '4 Host Program support' and fixed it up.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
These userspace programs include UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample programs should be built for
the target as well. Kbuild now supports 'userprogs' for that.
I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
The 'ifndef CROSS_COMPILE' is no longer needed.
BTW, the -m31 for s390 is left-over code. Commit 5a79859ae0 ("s390:
remove 31 bit support") killed it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
The user mode helper should be compiled for the same architecture as
the kernel.
This Makefile reused the 'hostprogs' syntax by overriding HOSTCC with CC.
Use the new syntax 'userprogs' to fix the Makefile mess.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Kbuild supports the infrastructure to build host programs, but there
was no support to build userspace programs for the target architecture
(i.e. the same architecture as the kernel).
Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154),
but it was not merged. One problem at that time was, there was no good way
to know whether $(CC) can link standalone programs. In fact, pre-built
kernel.org toolchains [1] are often used for building the kernel, but they
do not provide libc.
Now, we can handle this cleanly because the compiler capability is
evaluated at the Kconfig time. If $(CC) cannot link standalone programs,
the relevant options are hidden by 'depends on CC_CAN_LINK'.
The implementation just mimics scripts/Makefile.host
The userspace programs are compiled with the same flags as the host
programs. In addition, it uses -m32 or -m64 if it is found in
$(KBUILD_CFLAGS).
This new syntax has two usecases.
- Sample programs
Several userspace programs under samples/ include UAPI headers
installed in usr/include. Most of them were previously built for
the host architecture just to use the 'hostprogs' syntax.
However, 'make headers' always works for the target architecture.
This caused the arch mismatch in cross-compiling. To fix this
distortion, sample code should be built for the target architecture.
- Bpfilter
net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper,
and embeds it into the kernel. Currently, it overrides HOSTCC with
CC to use the 'hostprogs' syntax. This hack should go away.
[1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
On Fedora, linking static glibc requires the glibc-static RPM package,
which is not part of the glibc-devel package.
CONFIG_CC_CAN_LINK does not check the capability of static linking,
so you can enable CONFIG_BPFILTER_UMH, then fail to build:
HOSTLD net/bpfilter/bpfilter_umh
/usr/bin/ld: cannot find -lc
collect2: error: ld returned 1 exit status
Add CONFIG_CC_CAN_LINK_STATIC, and make CONFIG_BPFILTER_UMH depend
on it.
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
bpfilter_umh is built for the default machine bit of the compiler,
which may not match to the bit size of the kernel.
This happens in the scenario below:
You can use biarch GCC that defaults to 64-bit for building the 32-bit
kernel. In this case, Kbuild passes -m32 to teach the compiler to
produce 32-bit kernel space objects. However, it is missing when
building bpfilter_umh. It is built as a 64-bit ELF, and then embedded
into the 32-bit kernel.
The 32-bit kernel and 64-bit umh is a bad combination.
In theory, we can have 32-bit umh running on 64-bit kernel, but we do
not have a good reason to support such a usecase.
The best is to match the bit size between them.
Pass -m32 or -m64 to the umh build command if it is found in
$(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
always, hostprogs-y, and hostprogs-m are deprecated.
There is no user in upstream code, but I will keep them for external
modules. I want to remove them entirely someday. Prompt downstream
users for the migration.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
cmd_dtc takes the additional parameter $(2) to select the target
format, dtb or yaml. This makes things complicated when it is used
with cmd_and_fixdep and if_changed_rule. I actually stumbled on this.
See commit 3d4b223868 ("kbuild: fix DT binding schema rule again to
avoid needless rebuilds").
Extract the suffix part of the target instead of passing the parameter.
Fortunately, this works for both $(obj)/%.dtb and $(obj)/%.dt.yaml .
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
$(AS) is not used anywhere in the kernel build, hence commit
aa824e0c96 ("kbuild: remove AS variable") killed it.
Remove the left-over code in arch/{arm,arm64}/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Will Deacon <will@kernel.org>
This reverts commit 8728497895.
samples/ contains only sub-directories.
Because OBJECT_FILES_NON_STANDARD does not work recursively,
this line has no effect.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
scripts/mkcompile_h runs $(CC) just for getting the version string.
Reuse CONFIG_CC_VERSION_TEXT for optimization.
For GCC, this slightly changes the version string. I do not think it
is a big deal as we do not have the defined format for LINUX_COMPILER.
In fact, the recent commit 4dcc9a8844 ("kbuild: mkcompile_h:
Include $LD version in /proc/version") added the linker version.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This omits system headers from the generated header dependency.
System headers are not updated unless you upgrade the compiler. Nor do
they contain CONFIG options, so fixdep does not need to parse them.
Having said that, the effect of this optimization will be quite small
because the kernel code generally does not include system headers
except <stdarg.h>. Host programs include a lot of system headers,
but there are not so many in the kernel tree.
At first, keeping system headers in .*.cmd files might be useful to
detect the compiler update, but there is no guarantee that <stdarg.h>
is included from every file. So, I implemented a more reliable way in
the previous commit.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Commit 21c54b7747 ("kconfig: show compiler version text in the top
comment") added the environment variable, CC_VERSION_TEXT in the comment
of the top Kconfig file. It can detect the compiler update, and invoke
the syncconfig because all environment variables referenced in Kconfig
files are recorded in include/config/auto.conf.cmd
This commit makes it a CONFIG option in order to ensure the full rebuild
when the compiler is updated.
This works like follows:
include/config/kconfig.h contains "CONFIG_CC_VERSION_TEXT" in the comment
block.
The top Makefile specifies "-include $(srctree)/include/linux/kconfig.h"
to guarantee it is included from all kernel source files.
fixdep parses every source file and all headers included from it,
searching for words prefixed with "CONFIG_". Then, fixdep finds
CONFIG_CC_VERSION_TEXT in include/config/kconfig.h and adds
include/config/cc/version/text.h into every .*.cmd file.
When the compiler is updated, syncconfig is invoked because init/Kconfig
contains the reference to the environment variable CC_VERTION_TEXT.
CONFIG_CC_VERSION_TEXT is updated to the new version string, and
include/config/cc/version/text.h is touched.
In the next rebuild, Make will rebuild every files since the timestamp
of include/config/cc/version/text.h is newer than that of target.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The result of '$(CC) --version | head -n 1' has already been computed
by the top Makefile, and stored in the environment variable,
CC_VERSION_TEXT.
'echo' is cheaper than the two commands $(CC) and 'head' although this
optimization is not noticeable level.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Since commit a83e4ca26a ("kbuild: remove cc-option switch from
-Wframe-larger-than="), 'make ARCH=unicore32 clean' emits error
messages as follows:
$ make ARCH=unicore32 clean
gcc: error: missing argument to '-Wframe-larger-than='
gcc: error: missing argument to '-Wframe-larger-than='
We do not care compiler flags when cleaning.
Use the '=' operator for lazy expansion because we do not use
GNU_LIBC_A or GNU_LIBGCC_A when cleaning.
Fixes: a83e4ca26a ("kbuild: remove cc-option switch from -Wframe-larger-than=")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
'make ARCH=h8300 clean' emits error messages as follows:
$ make ARCH=h8300 clean
gcc: error: missing argument to '-Wframe-larger-than='
gcc: error: unrecognized command line option '-mint32'
You can suppress the second one by setting the correct CROSS_COMPILE=,
but we should not require any compiler for cleaning.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
'make ARCH=hexagon clean' emits an error message as follows:
$ make ARCH=hexagon clean
gcc: error: unrecognized command line option '-G0'
You can suppress it by setting the correct CROSS_COMPILE=,
but we should not require any compiler for cleaning.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Brian Cain <bcain@codeaurora.org>
Since commit a83e4ca26a ("kbuild: remove cc-option switch from
-Wframe-larger-than="), 'make ARCH=um clean' emits an error message
as follows:
$ make ARCH=um clean
gcc: error: missing argument to '-Wframe-larger-than='
We do not care compiler flags when cleaning.
Use the '=' operator for lazy expansion because we do not use
LDFLAGS_pcap.o or LDFLAGS_vde.o when cleaning.
While I was here, I removed the redundant -r option because it
already exists in the recipe.
Fixes: a83e4ca26a ("kbuild: remove cc-option switch from -Wframe-larger-than=")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com> [build]
- Ensure that direct mapping alias is always flushed when changing page
attributes. The optimization for small ranges failed to do so when
the virtual address was in the vmalloc or module space.
- Unbreak the trace event registration for syscalls without arguments
caused by the refactoring of the SYSCALL_DEFINE0() macro.
- Move the printk in the TSC deadline timer code to a place where it is
guaranteed to only be called once during boot and cannot be rearmed by
clearing warn_once after boot. If it's invoked post boot then lockdep
rightfully complains about a potential deadlock as the calling context
is different.
- A series of fixes for objtool and the ORC unwinder addressing variety
of small issues:
Stack offset tracking for indirect CFAs in objtool ignored subsequent
pushs and pops
Repair the unwind hints in the register clearing entry ASM code
Make the unwinding in the low level exit to usermode code stop after
switching to the trampoline stack. The unwind hint is not longer valid
and the ORC unwinder emits a warning as it can't find the registers
anymore.
Fix the unwind hints in switch_to_asm() and rewind_stack_do_exit()
which caused objtool to generate bogus ORC data.
Prevent unwinder warnings when dumping the stack of a non-current
task as there is no way to be sure about the validity because the
dumped stack can be a moving target.
Make the ORC unwinder behave the same way as the frame pointer
unwinder when dumping an inactive tasks stack and do not skip the
first frame.
Prevent ORC unwinding before ORC data has been initialized
Immediately terminate unwinding when a unknown ORC entry type is
found.
Prevent premature stop of the unwinder caused by IRET frames.
Fix another infinite loop in objtool caused by a negative offset which
was not catched.
Address a few build warnings in the ORC unwinder and add missing
static/ro_after_init annotations
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Merge tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
"A set of fixes for x86:
- Ensure that direct mapping alias is always flushed when changing
page attributes. The optimization for small ranges failed to do so
when the virtual address was in the vmalloc or module space.
- Unbreak the trace event registration for syscalls without arguments
caused by the refactoring of the SYSCALL_DEFINE0() macro.
- Move the printk in the TSC deadline timer code to a place where it
is guaranteed to only be called once during boot and cannot be
rearmed by clearing warn_once after boot. If it's invoked post boot
then lockdep rightfully complains about a potential deadlock as the
calling context is different.
- A series of fixes for objtool and the ORC unwinder addressing
variety of small issues:
- Stack offset tracking for indirect CFAs in objtool ignored
subsequent pushs and pops
- Repair the unwind hints in the register clearing entry ASM code
- Make the unwinding in the low level exit to usermode code stop
after switching to the trampoline stack. The unwind hint is no
longer valid and the ORC unwinder emits a warning as it can't
find the registers anymore.
- Fix unwind hints in switch_to_asm() and rewind_stack_do_exit()
which caused objtool to generate bogus ORC data.
- Prevent unwinder warnings when dumping the stack of a
non-current task as there is no way to be sure about the
validity because the dumped stack can be a moving target.
- Make the ORC unwinder behave the same way as the frame pointer
unwinder when dumping an inactive tasks stack and do not skip
the first frame.
- Prevent ORC unwinding before ORC data has been initialized
- Immediately terminate unwinding when a unknown ORC entry type
is found.
- Prevent premature stop of the unwinder caused by IRET frames.
- Fix another infinite loop in objtool caused by a negative
offset which was not catched.
- Address a few build warnings in the ORC unwinder and add
missing static/ro_after_init annotations"
* tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/unwind/orc: Move ORC sorting variables under !CONFIG_MODULES
x86/apic: Move TSC deadline timer debug printk
ftrace/x86: Fix trace event registration for syscalls without arguments
x86/mm/cpa: Flush direct map alias during cpa
objtool: Fix infinite loop in for_offset_range()
x86/unwind/orc: Fix premature unwind stoppage due to IRET frames
x86/unwind/orc: Fix error path for bad ORC entry type
x86/unwind/orc: Prevent unwinding before ORC initialization
x86/unwind/orc: Don't skip the first frame for inactive tasks
x86/unwind: Prevent false warnings for non-current tasks
x86/unwind/orc: Convert global variables to static
x86/entry/64: Fix unwind hints in rewind_stack_do_exit()
x86/entry/64: Fix unwind hints in __switch_to_asm()
x86/entry/64: Fix unwind hints in kernel exit path
x86/entry/64: Fix unwind hints in register clearing code
objtool: Fix stack offset tracking for indirect CFAs
search which can be triggered when building the kernel with
-ffunction-sections.
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Merge tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fix from Thomas Gleixner:
"A single fix for objtool to prevent an infinite loop in the
jump table search which can be triggered when building the
kernel with '-ffunction-sections'"
* tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix infinite loop in find_jump_table()
With those changes GCC9 fails to analyze arch_futex_atomic_op_inuser()
correctly and emits a 'maybe unitialized' warning. While we usually ignore
compiler stupidity the conditional store is pointless anyway because the
correct case has to store. For the fault case the extra store does no harm.
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Merge tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Thomas Gleixner:
"A single fix for the fallout of the recent futex uacess rework.
With those changes GCC9 fails to analyze arch_futex_atomic_op_inuser()
correctly and emits a 'maybe unitialized' warning. While we usually
ignore compiler stupidity the conditional store is pointless anyway
because the correct case has to store. For the fault case the extra
store does no harm"
* tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ARM: futex: Address build warning
Including:
- The race condition fixes for the AMD IOMMU driver. This are 5
patches fixing two race conditions around
increase_address_space(). The first race condition was around
the non-atomic update of the domain page-table root pointer
and the variable containing the page-table depth (called
mode). This is fixed now be merging page-table root and mode
into one 64-bit field which is read/written atomically.
The second race condition was around updating the page-table
root pointer and making it public before the hardware caches
were flushed. This could cause addresses to be mapped and
returned to drivers which are not reachable by IOMMU hardware
yet, causing IO page-faults. This is fixed too by adding the
necessary flushes before a new page-table root is published.
Related to the race condition fixes these patches also add a
missing domain_flush_complete() barrier to update_domain() and
a fix to bail out of the loop which tries to increase the
address space when the call to increase_address_space() fails.
Qian was able to trigger the race conditions under high load
and memory pressure within a few days of testing. He confirmed
that he has seen no issues anymore with the fixes included
here.
- Fix for a list-handling bug in the VirtIO IOMMU driver.
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Merge tag 'iommu-fixes-v5.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu
Pull iommu fixes from Joerg Roedel:
- Race condition fixes for the AMD IOMMU driver.
These are five patches fixing two race conditions around
increase_address_space(). The first race condition was around the
non-atomic update of the domain page-table root pointer and the
variable containing the page-table depth (called mode). This is fixed
now be merging page-table root and mode into one 64-bit field which
is read/written atomically.
The second race condition was around updating the page-table root
pointer and making it public before the hardware caches were flushed.
This could cause addresses to be mapped and returned to drivers which
are not reachable by IOMMU hardware yet, causing IO page-faults. This
is fixed too by adding the necessary flushes before a new page-table
root is published.
Related to the race condition fixes these patches also add a missing
domain_flush_complete() barrier to update_domain() and a fix to bail
out of the loop which tries to increase the address space when the
call to increase_address_space() fails.
Qian was able to trigger the race conditions under high load and
memory pressure within a few days of testing. He confirmed that he
has seen no issues anymore with the fixes included here.
- Fix for a list-handling bug in the VirtIO IOMMU driver.
* tag 'iommu-fixes-v5.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
iommu/virtio: Reverse arguments to list_add
iommu/amd: Do not flush Device Table in iommu_map_page()
iommu/amd: Update Device Table in increase_address_space()
iommu/amd: Call domain_flush_complete() in update_domain()
iommu/amd: Do not loop forever when trying to increase address space
iommu/amd: Fix race in increase_address_space()/fetch_pte()
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Merge tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
- a small series fixing a use-after-free of bdi name (Christoph,Yufen)
- NVMe fix for a regression with the smaller CQ update (Alexey)
- NVMe fix for a hang at namespace scanning error recovery (Sagi)
- fix race with blk-iocost iocg->abs_vdebt updates (Tejun)
* tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block:
nvme: fix possible hang when ns scanning fails during error recovery
nvme-pci: fix "slimmer CQ head update"
bdi: add a ->dev_name field to struct backing_dev_info
bdi: use bdi_dev_name() to get device name
bdi: move bdi_dev_name out of line
vboxsf: don't use the source name in the bdi name
iocost: protect iocg->abs_vdebt with iocg->waitq.lock
It seems that for whatever reason, gcc-10 ends up not inlining a couple
of functions that used to be inlined before. Even if they only have one
single callsite - it looks like gcc may have decided that the code was
unlikely, and not worth inlining.
The code generation difference is harmless, but caused a few new section
mismatch errors, since the (now no longer inlined) function wasn't in
the __init section, but called other init functions:
Section mismatch in reference from the function kexec_free_initrd() to the function .init.text:free_initrd_mem()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memremap()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memunmap()
So add the appropriate __init annotation to make modpost not complain.
In both cases there were trivially just a single callsite from another
__init function.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This contains a smattering of fixes and cleanups that I'd like to target for
5.7:
* Dead code removal.
* Exporting riscv_cpuid_to_hartid_mask for modules.
* Per-CPU tracking of ISA features.
* Setting max_pfn correctly when probing memory.
* Adding a note to the VDSO so glibc can check the kernel's version without a
uname().
* A fix to force the bootloader to initialize the boot spin tables, which still
get used as a fallback when SBI-0.1 is enabled.
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Merge tag 'riscv-for-linus-5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V fixes from Palmer Dabbelt:
"A smattering of fixes and cleanups:
- Dead code removal.
- Exporting riscv_cpuid_to_hartid_mask for modules.
- Per-CPU tracking of ISA features.
- Setting max_pfn correctly when probing memory.
- Adding a note to the VDSO so glibc can check the kernel's version
without a uname().
- A fix to force the bootloader to initialize the boot spin tables,
which still get used as a fallback when SBI-0.1 is enabled"
* tag 'riscv-for-linus-5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
RISC-V: Remove unused code from STRICT_KERNEL_RWX
riscv: force __cpu_up_ variables to put in data section
riscv: add Linux note to vdso
riscv: set max_pfn to the PFN of the last page
RISC-V: Remove N-extension related defines
RISC-V: Add bitmap reprensenting ISA features common across CPUs
RISC-V: Export riscv_cpuid_to_hartid_mask() API
gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.
This results in warnings like:
crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]
because the crypto layer had its local freeing functions called
'free()'.
Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.
But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.
[ Side note: gcc knowing about 'free()' is in itself not the
mis-feature: the semantics of 'free()' are special enough that a
compiler can validly do special things when seeing it.
So the mis-feature here is that gcc thinks that 'free()' is some
restricted name, and you can't shadow it as a local static function.
Making the special 'free()' semantics be a function attribute rather
than tied to the name would be the much better model ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gcc-10 now warns about passing aliasing pointers to functions that take
restricted pointers.
That's actually a great warning, and if we ever start using 'restrict'
in the kernel, it might be quite useful. But right now we don't, and it
turns out that the only thing this warns about is an idiom where we have
declared a few functions to be "printf-like" (which seems to make gcc
pick up the restricted pointer thing), and then we print to the same
buffer that we also use as an input.
And people do that as an odd concatenation pattern, with code like this:
#define sysfs_show_gen_prop(buffer, fmt, ...) \
snprintf(buffer, PAGE_SIZE, "%s"fmt, buffer, __VA_ARGS__)
where we have 'buffer' as both the destination of the final result, and
as the initial argument.
Yes, it's a bit questionable. And outside of the kernel, people do have
standard declarations like
int snprintf( char *restrict buffer, size_t bufsz,
const char *restrict format, ... );
where that output buffer is marked as a restrict pointer that cannot
alias with any other arguments.
But in the context of the kernel, that 'use snprintf() to concatenate to
the end result' does work, and the pattern shows up in multiple places.
And we have not marked our own version of snprintf() as taking restrict
pointers, so the warning is incorrect for now, and gcc picks it up on
its own.
If we do start using 'restrict' in the kernel (and it might be a good
idea if people find places where it matters), we'll need to figure out
how to avoid this issue for snprintf and friends. But in the meantime,
this warning is not useful.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the final array bounds warning removal for gcc-10 for now.
Again, the warning is good, and we should re-enable all these warnings
when we have converted all the legacy array declaration cases to
flexible arrays. But in the meantime, it's just noise.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the controller is reconnecting, the host fails I/O and admin
commands as the host cannot reach the controller. ns scanning may
revalidate namespaces during that period and it is wrong to remove
namespaces due to these failures as we may hang (see 205da24343).
One command that may fail is nvme_identify_ns_descs. Since we return
success due to having ns identify descriptor list optional, we continue
to compare ns identifiers in nvme_revalidate_disk, obviously fail and
return -ENODEV to nvme_validate_ns, which will remove the namespace.
Exactly what we don't want to happen.
Fixes: 22802bf742 ("nvme: Namepace identification descriptor list is optional")
Tested-by: Anton Eidelman <anton@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pre-incrementing ->cq_head can't be done in memory because OOB value
can be observed by another context.
This devalues space savings compared to original code :-\
$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-32 (-32)
Function old new delta
nvme_poll_irqdisable 464 456 -8
nvme_poll 455 447 -8
nvme_irq 388 380 -8
nvme_dev_disable 955 947 -8
But the code is minimal now: one read for head, one read for q_depth,
one increment, one comparison, single instruction phase bit update and
one write for new head.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: John Garry <john.garry@huawei.com>
Tested-by: John Garry <john.garry@huawei.com>
Fixes: e2a366a4b0 ("nvme-pci: slimmer CQ head update")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.
Fixes: 68f23b8906 ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use the common interface bdi_dev_name() to get device name.
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Add missing <linux/backing-dev.h> include BFQ
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is another fine warning, related to the 'zero-length-bounds' one,
but hitting the same historical code in the kernel.
Because C didn't historically support flexible array members, we have
code that instead uses a one-sized array, the same way we have cases of
zero-sized arrays.
The one-sized arrays come from either not wanting to use the gcc
zero-sized array extension, or from a slight convenience-feature, where
particularly for strings, the size of the structure now includes the
allocation for the final NUL character.
So with a "char name[1];" at the end of a structure, you can do things
like
v = my_malloc(sizeof(struct vendor) + strlen(name));
and avoid the "+1" for the terminator.
Yes, the modern way to do that is with a flexible array, and using
'offsetof()' instead of 'sizeof()', and adding the "+1" by hand. That
also technically gets the size "more correct" in that it avoids any
alignment (and thus padding) issues, but this is another long-term
cleanup thing that will not happen for 5.7.
So disable the warning for now, even though it's potentially quite
useful. Having a slew of warnings that then hide more urgent new issues
is not an improvement.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
