Rework the defintion of struct siginfo so that the array padding
struct siginfo to SI_MAX_SIZE can be placed in a union along side of
the rest of the struct siginfo members. The result is that we no
longer need the __ARCH_SI_PREAMBLE_SIZE or SI_PAD_SIZE definitions.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
When moving all of the architectures specific si_codes into
siginfo.h, I apparently overlooked EMT_TAGOVF. Move it now.
Remove the now redundant test in siginfo_layout for SIGEMT
as now NSIGEMT is always defined.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Both powerpc and alpha have cases where they wronly set si_code to 0
in combination with SIGTRAP and don't mean SI_USER.
About half the time this is because the architecture can not report
accurately what kind of trap exception triggered the trap exception.
The other half the time it looks like no one has bothered to
figure out an appropriate si_code.
For the cases where the architecture does not have enough information
or is too lazy to figure out exactly what kind of trap exception
it is define TRAP_UNK.
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Posix and common sense requires that SI_USER not be a signal specific
si_code. Thus add a new FPE_CONDTRAP si_code for conditional traps.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Pull siginfo updates from Eric Biederman:
"The work on cleaning up and getting the bugs out of siginfo generation
was largely stalled this round. The progress that was made was the
definition of FPE_FLTUNK. Which is usable to fix many of the cases
where siginfo generation is erroneously generating SI_USER by setting
si_code to 0, that has recently been tagged as FPE_FIXME.
You already have the change by way of the arm64 tree as that
definition was pulled into the arm64 tree to allow fixing the problem
there.
What remains is the second round of fixing for what I thought was a
trivial change to the struct siginfo when put the union in _sigfault
where it belongs. Do to historical reasons 32bit m68k only ensures
that pointers are 2 byte aligned. So I have added a m68k test case
made of BUILD_BUG_ONs to verify I have this fix correct and possibly
catch problems, and I have computed the number of bytes of padding
needed for the _addr_bnd and _addr_pkey cases and just use an array of
characters that size.
For pure paranoia I have written the code so if there is an
architecture out there that does not perform any alignment of
structures it should still work.
With the removal of all of the stale arechitectures this cycle future
work on cleaning up struct siginfo should be much easier. Almost all
of the conflicting si_code definitions have been removed with the
removal of (blackfin, tile, and frv). Plus some of the most difficult
to test cases have simply been removed from the tree.
Which means that with a little luck copy_siginfo_to_user can become a
light weight wrapper around copy_to_user in the next cycle"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
m68k: Verify the offsets in struct siginfo never change.
signal: Correct the offset of si_pkey and si_lower in struct siginfo on m68k
Nothing particularly stands out here, probably because people were tied
up with spectre/meltdown stuff last time around. Still, the main pieces
are:
- Rework of our CPU features framework so that we can whitelist CPUs that
don't require kpti even in a heterogeneous system
- Support for the IDC/DIC architecture extensions, which allow us to elide
instruction and data cache maintenance when writing out instructions
- Removal of the large memory model which resulted in suboptimal codegen
by the compiler and increased the use of literal pools, which could
potentially be used as ROP gadgets since they are mapped as executable
- Rework of forced signal delivery so that the siginfo_t is well-formed
and handling of show_unhandled_signals is consolidated and made
consistent between different fault types
- More siginfo cleanup based on the initial patches from Eric Biederman
- Workaround for Cortex-A55 erratum #1024718
- Some small ACPI IORT updates and cleanups from Lorenzo Pieralisi
- Misc cleanups and non-critical fixes
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"Nothing particularly stands out here, probably because people were
tied up with spectre/meltdown stuff last time around. Still, the main
pieces are:
- Rework of our CPU features framework so that we can whitelist CPUs
that don't require kpti even in a heterogeneous system
- Support for the IDC/DIC architecture extensions, which allow us to
elide instruction and data cache maintenance when writing out
instructions
- Removal of the large memory model which resulted in suboptimal
codegen by the compiler and increased the use of literal pools,
which could potentially be used as ROP gadgets since they are
mapped as executable
- Rework of forced signal delivery so that the siginfo_t is
well-formed and handling of show_unhandled_signals is consolidated
and made consistent between different fault types
- More siginfo cleanup based on the initial patches from Eric
Biederman
- Workaround for Cortex-A55 erratum #1024718
- Some small ACPI IORT updates and cleanups from Lorenzo Pieralisi
- Misc cleanups and non-critical fixes"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (70 commits)
arm64: uaccess: Fix omissions from usercopy whitelist
arm64: fpsimd: Split cpu field out from struct fpsimd_state
arm64: tlbflush: avoid writing RES0 bits
arm64: cmpxchg: Include linux/compiler.h in asm/cmpxchg.h
arm64: move percpu cmpxchg implementation from cmpxchg.h to percpu.h
arm64: cmpxchg: Include build_bug.h instead of bug.h for BUILD_BUG
arm64: lse: Include compiler_types.h and export.h for out-of-line LL/SC
arm64: fpsimd: include <linux/init.h> in fpsimd.h
drivers/perf: arm_pmu_platform: do not warn about affinity on uniprocessor
perf: arm_spe: include linux/vmalloc.h for vmap()
Revert "arm64: Revert L1_CACHE_SHIFT back to 6 (64-byte cache line size)"
arm64: cpufeature: Avoid warnings due to unused symbols
arm64: Add work around for Arm Cortex-A55 Erratum 1024718
arm64: Delay enabling hardware DBM feature
arm64: Add MIDR encoding for Arm Cortex-A55 and Cortex-A35
arm64: capabilities: Handle shared entries
arm64: capabilities: Add support for checks based on a list of MIDRs
arm64: Add helpers for checking CPU MIDR against a range
arm64: capabilities: Clean up midr range helpers
arm64: capabilities: Change scope of VHE to Boot CPU feature
...
Pull sparc updates from David Miller:
1) Add support for ADI (Application Data Integrity) found in more
recent sparc64 cpus. Essentially this is keyed based access to
virtual memory, and if the key encoded in the virual address is
wrong you get a trap.
The mm changes were reviewed by Andrew Morton and others.
Work by Khalid Aziz.
2) Validate DAX completion index range properly, from Rob Gardner.
3) Add proper Kconfig deps for DAX driver. From Guenter Roeck.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next:
sparc64: Make atomic_xchg() an inline function rather than a macro.
sparc64: Properly range check DAX completion index
sparc: Make auxiliary vectors for ADI available on 32-bit as well
sparc64: Oracle DAX driver depends on SPARC64
sparc64: Update signal delivery to use new helper functions
sparc64: Add support for ADI (Application Data Integrity)
mm: Allow arch code to override copy_highpage()
mm: Clear arch specific VM flags on protection change
mm: Add address parameter to arch_validate_prot()
sparc64: Add auxiliary vectors to report platform ADI properties
sparc64: Add handler for "Memory Corruption Detected" trap
sparc64: Add HV fault type handlers for ADI related faults
sparc64: Add support for ADI register fields, ASIs and traps
mm, swap: Add infrastructure for saving page metadata on swap
signals, sparc: Add signal codes for ADI violations
This removes the entire architecture code for blackfin, cris, frv, m32r,
metag, mn10300, score, and tile, including the associated device drivers.
I have been working with the (former) maintainers for each one to ensure
that my interpretation was right and the code is definitely unused in
mainline kernels. Many had fond memories of working on the respective
ports to start with and getting them included in upstream, but also saw
no point in keeping the port alive without any users.
In the end, it seems that while the eight architectures are extremely
different, they all suffered the same fate: There was one company
in charge of an SoC line, a CPU microarchitecture and a software
ecosystem, which was more costly than licensing newer off-the-shelf
CPU cores from a third party (typically ARM, MIPS, or RISC-V). It seems
that all the SoC product lines are still around, but have not used the
custom CPU architectures for several years at this point. In contrast,
CPU instruction sets that remain popular and have actively maintained
kernel ports tend to all be used across multiple licensees.
The removal came out of a discussion that is now documented at
https://lwn.net/Articles/748074/. Unlike the original plans, I'm not
marking any ports as deprecated but remove them all at once after I made
sure that they are all unused. Some architectures (notably tile, mn10300,
and blackfin) are still being shipped in products with old kernels,
but those products will never be updated to newer kernel releases.
After this series, we still have a few architectures without mainline
gcc support:
- unicore32 and hexagon both have very outdated gcc releases, but the
maintainers promised to work on providing something newer. At least
in case of hexagon, this will only be llvm, not gcc.
- openrisc, risc-v and nds32 are still in the process of finishing their
support or getting it added to mainline gcc in the first place.
They all have patched gcc-7.3 ports that work to some degree, but
complete upstream support won't happen before gcc-8.1. Csky posted
their first kernel patch set last week, their situation will be similar.
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Merge tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pul removal of obsolete architecture ports from Arnd Bergmann:
"This removes the entire architecture code for blackfin, cris, frv,
m32r, metag, mn10300, score, and tile, including the associated device
drivers.
I have been working with the (former) maintainers for each one to
ensure that my interpretation was right and the code is definitely
unused in mainline kernels. Many had fond memories of working on the
respective ports to start with and getting them included in upstream,
but also saw no point in keeping the port alive without any users.
In the end, it seems that while the eight architectures are extremely
different, they all suffered the same fate: There was one company in
charge of an SoC line, a CPU microarchitecture and a software
ecosystem, which was more costly than licensing newer off-the-shelf
CPU cores from a third party (typically ARM, MIPS, or RISC-V). It
seems that all the SoC product lines are still around, but have not
used the custom CPU architectures for several years at this point. In
contrast, CPU instruction sets that remain popular and have actively
maintained kernel ports tend to all be used across multiple licensees.
[ See the new nds32 port merged in the previous commit for the next
generation of "one company in charge of an SoC line, a CPU
microarchitecture and a software ecosystem" - Linus ]
The removal came out of a discussion that is now documented at
https://lwn.net/Articles/748074/. Unlike the original plans, I'm not
marking any ports as deprecated but remove them all at once after I
made sure that they are all unused. Some architectures (notably tile,
mn10300, and blackfin) are still being shipped in products with old
kernels, but those products will never be updated to newer kernel
releases.
After this series, we still have a few architectures without mainline
gcc support:
- unicore32 and hexagon both have very outdated gcc releases, but the
maintainers promised to work on providing something newer. At least
in case of hexagon, this will only be llvm, not gcc.
- openrisc, risc-v and nds32 are still in the process of finishing
their support or getting it added to mainline gcc in the first
place. They all have patched gcc-7.3 ports that work to some
degree, but complete upstream support won't happen before gcc-8.1.
Csky posted their first kernel patch set last week, their situation
will be similar
[ Palmer Dabbelt points out that RISC-V support is in mainline gcc
since gcc-7, although gcc-7.3.0 is the recommended minimum - Linus ]"
This really says it all:
2498 files changed, 95 insertions(+), 467668 deletions(-)
* tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (74 commits)
MAINTAINERS: UNICORE32: Change email account
staging: iio: remove iio-trig-bfin-timer driver
tty: hvc: remove tile driver
tty: remove bfin_jtag_comm and hvc_bfin_jtag drivers
serial: remove tile uart driver
serial: remove m32r_sio driver
serial: remove blackfin drivers
serial: remove cris/etrax uart drivers
usb: Remove Blackfin references in USB support
usb: isp1362: remove blackfin arch glue
usb: musb: remove blackfin port
usb: host: remove tilegx platform glue
pwm: remove pwm-bfin driver
i2c: remove bfin-twi driver
spi: remove blackfin related host drivers
watchdog: remove bfin_wdt driver
can: remove bfin_can driver
mmc: remove bfin_sdh driver
input: misc: remove blackfin rotary driver
input: keyboard: remove bf54x driver
...
The change moving addr_lsb into the _sigfault union failed to take
into account that _sigfault._addr_bnd._lower being a pointer forced
the entire union to have pointer alignment. The fix for
_sigfault._addr_bnd._lower having pointer alignment failed to take
into account that m68k has a pointer alignment less than the size
of a pointer. So simply making the padding members pointers changed
the location of later members in the structure.
Fix this by directly computing the needed size of the padding members,
and making the padding members char arrays of the needed size. AKA
if __alignof__(void *) is 1 sizeof(short) otherwise __alignof__(void *).
Which should be exactly the same rules the compiler whould have
used when computing the padding.
I have tested this change by adding BUILD_BUG_ONs to m68k to verify
the offset of every member of struct siginfo, and with those testing
that the offsets of the fields in struct siginfo is the same before
I changed the generic _sigfault member and after the correction
to the _sigfault member.
I have also verified that the x86 with it's own BUILD_BUG_ONs to verify
the offsets of the siginfo members also compiles cleanly.
Cc: stable@vger.kernel.org
Reported-by: Eugene Syromiatnikov <esyr@redhat.com>
Fixes: 859d880cf5 ("signal: Correct the offset of si_pkey in struct siginfo")
Fixes: b68a68d3dc ("signal: Move addr_lsb into the _sigfault union for clarity")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Unlike system call numbers the assignment of si_codes has never had a
reason to be made per architecture. Some architectures have had unique
conditions to report and reporting those conditions needed new si_codes.
Nothing has ever needed si_codes to have different values on different
architectures. The si_code space is vast so even with defining all
si_codes on all architectures there is no danger in running out of
si_code values.
The history of the si_codes BUS_MCEERR_AR, BUS_MCEER_AO, SEGV_BNDERR,
and SEGV_PKUERR show that a need of one architecture frequently becomes
a need of another architecture which makes sharing si_codes between
architectures a positive benefit and something to be encouraged.
Where there are no conflicts with the historical ia64 arch specific
si_codes and any other si_codes make them generic si_codes. We might
need them on another architecture someday.
This leaves only the good example of arch generic si_codes in the kernel
for future architectures and architecture enhancments to follow.
Without bad examples to follow it should be easy to avoid the mistakes
of the past.
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
[arnd: took Eric's changelog text]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The frv, tile and blackfin architectures are being removed, so
we can clean up this header by removing all the special cases
except those for ia64.
The SEGV_BNDERR and BUS_MCEERR_AR si_code macros are now
defined unconditionally on all remaining architectures.
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
SPARC M7 processor introduces a new feature - Application Data
Integrity (ADI). ADI allows MMU to catch rogue accesses to memory.
When a rogue access occurs, MMU blocks the access and raises an
exception. In response to the exception, kernel sends the offending
task a SIGSEGV with si_code that indicates the nature of exception.
This patch adds three new signal codes specific to ADI feature:
1. ADI is not enabled for the address and task attempted to access
memory using ADI
2. Task attempted to access memory using wrong ADI tag and caused
a deferred exception.
3. Task attempted to access memory using wrong ADI tag and caused
a precise exception.
Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Khalid Aziz <khalid@gonehiking.org>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some architectures cannot always report accurately what kind of
floating-point exception triggered a floating-point exception trap.
This can occur with fp exceptions occurring on lanes in a vector
instruction on arm64 for example.
Rather than have every architecture come up with its own way of
describing such a condition, this patch adds a common FPE_FLTUNK
si_code value to report that an fp exception caused a trap but we
cannot be certain which kind of fp exception it was.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
The change moving addr_lsb into the _sigfault union failed to take
into account that _sigfault._addr_bnd._lower being a pointer forced
the entire union to have pointer alignment. In practice this only
mattered for the offset of si_pkey which is why this has taken so long
to discover.
To correct this change _dummy_pkey and _dummy_bnd to have pointer type.
Reported-by: kernel test robot <shun.hao@intel.com>
Fixes: b68a68d3dc ("signal: Move addr_lsb into the _sigfault union for clarity")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Fix grammar and add an omitted word.
Link: http://lkml.kernel.org/r/1a5a021c-0207-f793-7f07-addca26772d5@infradead.org
Fixes: f9886bc50a ("signal: Document the strange si_codes used by ptrace event stops")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Having si_codes in many different files simply encourages duplicate definitions
that can cause problems later. To avoid that merge the blackfin specific si_codes
into uapi/asm-generic/siginfo.h
Update copy_siginfo_to_user to copy with the absence of BUS_MCEERR_AR that blackfin
defines to be something else.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Having si_codes in many different files simply encourages duplicate definitions
that can cause problems later. To avoid that merge the tile specific si_codes
into uapi/asm-generic/siginfo.h
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Having si_codes in many different files simply encourages duplicate definitions
that can cause problems later. To avoid that merce the frv specific si_codes
into uapi/asm-generic/siginfo.h
This allows the removal of arch/frv/uapi/include/asm/siginfo.h as the last
last meaningful definition it held was FPE_MDAOVF.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Having si_codes in many different files simply encourages duplicate
definitions that can cause problems later. To avoid that merge the
ia64 specific si_codes into uapi/asm-generic/siginfo.h
Update the sanity checks in arch/x86/kernel/signal_compat.c to expect
the now lager NSIGILL and NSIGFPE. As nothing excpe the larger count
is exposed on x86 no additional code needs to be updated.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The addr_lsb fields is only valid and available when the
signal is SIGBUS and the si_code is BUS_MCEERR_AR or BUS_MCEERR_AO.
Document this with a comment and place the field in the _sigfault union
to make this clear.
All of the fields stay in the same physical location so both the old
and new definitions of struct siginfo will continue to work.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
... having taught the latter that si_errno and si_code might be
swapped.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
... at a cost of added small ifdef __ia64__ in asm-generic siginfo.h,
that is.
-- EWB Corrected the comment on _flags to reflect the move
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The header uapi/asm-generic/siginfo.h appears to the the repository of
all of these definitions in linux so collect up glibcs additions as
well. Just to prevent someone from accidentally creating a conflict
in the future.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.
By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:
NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".
otherwise syscall usage would not be possible.
Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
struct siginfo is a union and the kernel since 2.4 has been hiding a union
tag in the high 16bits of si_code using the values:
__SI_KILL
__SI_TIMER
__SI_POLL
__SI_FAULT
__SI_CHLD
__SI_RT
__SI_MESGQ
__SI_SYS
While this looks plausible on the surface, in practice this situation has
not worked well.
- Injected positive signals are not copied to user space properly
unless they have these magic high bits set.
- Injected positive signals are not reported properly by signalfd
unless they have these magic high bits set.
- These kernel internal values leaked to userspace via ptrace_peek_siginfo
- It was possible to inject these kernel internal values and cause the
the kernel to misbehave.
- Kernel developers got confused and expected these kernel internal values
in userspace in kernel self tests.
- Kernel developers got confused and set si_code to __SI_FAULT which
is SI_USER in userspace which causes userspace to think an ordinary user
sent the signal and that it was not kernel generated.
- The values make it impossible to reorganize the code to transform
siginfo_copy_to_user into a plain copy_to_user. As si_code must
be massaged before being passed to userspace.
So remove these kernel internal si codes and make the kernel code simpler
and more maintainable.
To replace these kernel internal magic si_codes introduce the helper
function siginfo_layout, that takes a signal number and an si_code and
computes which union member of siginfo is being used. Have
siginfo_layout return an enumeration so that gcc will have enough
information to warn if a switch statement does not handle all of union
members.
A couple of architectures have a messed up ABI that defines signal
specific duplications of SI_USER which causes more special cases in
siginfo_layout than I would like. The good news is only problem
architectures pay the cost.
Update all of the code that used the previous magic __SI_ values to
use the new SIL_ values and to call siginfo_layout to get those
values. Escept where not all of the cases are handled remove the
defaults in the switch statements so that if a new case is missed in
the future the lack will show up at compile time.
Modify the code that copies siginfo si_code to userspace to just copy
the value and not cast si_code to a short first. The high bits are no
longer used to hold a magic union member.
Fixup the siginfo header files to stop including the __SI_ values in
their constants and for the headers that were missing it to properly
update the number of si_codes for each signal type.
The fixes to copy_siginfo_from_user32 implementations has the
interesting property that several of them perviously should never have
worked as the __SI_ values they depended up where kernel internal.
With that dependency gone those implementations should work much
better.
The idea of not passing the __SI_ values out to userspace and then
not reinserting them has been tested with criu and criu worked without
changes.
Ref: 2.4.0-test1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
We have a weird and problematic intersection of features that when
they all come together result in ambiguous siginfo values, that
we can not support properly.
- Supporting fcntl(F_SETSIG,...) with arbitrary valid signals.
- Using positive values for POLL_IN, POLL_OUT, POLL_MSG, ..., etc
that imply they are signal specific si_codes and using the
aforementioned arbitrary signal to deliver them.
- Supporting injection of arbitrary siginfo values for debugging and
checkpoint/restore.
The result is that just looking at siginfo si_codes of 1 to 6 are
ambigious. It could either be a signal specific si_code or it could
be a generic si_code.
For most of the kernel this is a non-issue but for sending signals
with siginfo it is impossible to play back the kernel signals and
get the same result.
Strictly speaking when the si_code was changed from SI_SIGIO to
POLL_IN and friends between 2.2 and 2.4 this functionality was not
ambiguous, as only real time signals were supported. Before 2.4 was
released the kernel began supporting siginfo with non realtime signals
so they could give details of why the signal was sent.
The result is that if F_SETSIG is set to one of the signals with signal
specific si_codes then user space can not know why the signal was sent.
I grepped through a bunch of userspace programs using debian code
search to get a feel for how often people choose a signal that results
in an ambiguous si_code. I only found one program doing so and it was
using SIGCHLD to test the F_SETSIG functionality, and did not appear
to be a real world usage.
Therefore the ambiguity does not appears to be a real world problem in
practice. Remove the ambiguity while introducing the smallest chance
of breakage by changing the si_code to SI_SIGIO when signals with
signal specific si_codes are targeted.
Fixes: v2.3.40 -- Added support for queueing non-rt signals
Fixes: v2.3.21 -- Changed the si_code from SI_SIGIO
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
By moving the kernel side __SI_* defintions right next to the userspace
ones we can kill the non-uapi versions of <asm/siginfo.h> include
include/asm-generic/siginfo.h and untangle the unholy mess of includes.
[ tglx: Removed uapi/asm/siginfo.h from m32r, microblaze, mn10300 and score ]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20170603190102.28866-6-hch@lst.de
Stephen Rothwell reported this linux-next build failure:
http://lkml.kernel.org/r/20160226164406.065a1ffc@canb.auug.org.au
... caused by the Memory Protection Keys patches from the tip tree triggering
a newly introduced build-time sanity check on an ARM build, because they changed
the ABI of siginfo in an unexpected way.
If u64 has a natural alignment of 8 bytes (which is the case on most mainstream
platforms, with the notable exception of x86-32), then the leadup to the
_sifields union matters:
typedef struct siginfo {
int si_signo;
int si_errno;
int si_code;
union {
...
} _sifields;
} __ARCH_SI_ATTRIBUTES siginfo_t;
Note how the first 3 fields give us 12 bytes, so _sifields is not 8
naturally bytes aligned.
Before the _pkey field addition the largest element of _sifields (on
32-bit platforms) was 32 bits. With the u64 added, the minimum alignment
requirement increased to 8 bytes on those (rare) 32-bit platforms. Thus
GCC padded the space after si_code with 4 extra bytes, and shifted all
_sifields offsets by 4 bytes - breaking the ABI of all of those
remaining fields.
On 64-bit platforms this problem was hidden due to _sifields already
having numerous fields with natural 8 bytes alignment (pointers).
To fix this, we replace the u64 with an '__u32'. The __u32 does not
increase the minimum alignment requirement of the union, and it is
also large enough to store the 16-bit pkey we have today on x86.
Reported-by: Stehen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Stehen Rothwell <sfr@canb.auug.org.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Helge Deller <deller@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-next@vger.kernel.org
Fixes: cd0ea35ff5 ("signals, pkeys: Notify userspace about protection key faults")
Link: http://lkml.kernel.org/r/20160301125451.02C7426D@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A protection key fault is very similar to any other access error.
There must be a VMA, etc... We even want to take the same action
(SIGSEGV) that we do with a normal access fault.
However, we do need to let userspace know that something is
different. We do this the same way what we did with SEGV_BNDERR
with Memory Protection eXtensions (MPX): define a new SEGV code:
SEGV_PKUERR.
We add a siginfo field: si_pkey that reveals to userspace which
protection key was set on the PTE that we faulted on. There is
no other easy way for userspace to figure this out. They could
parse smaps but that would be a bit cruel.
We share space with in siginfo with _addr_bnd. #BR faults from
MPX are completely separate from page faults (#PF) that trigger
from protection key violations, so we never need both at the same
time.
Note that _pkey is a 64-bit value. The current hardware only
supports 4-bit protection keys. We do this because there is
_plenty_ of space in _sigfault and it is possible that future
processors would support more than 4 bits of protection keys.
The x86 code to actually fill in the siginfo is in the next
patch.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amanieu d'Antras <amanieu@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
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: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210212.3A9B83AC@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch adds new fields about bound violation into siginfo
structure. si_lower and si_upper are respectively lower bound
and upper bound when bound violation is caused.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151819.1908C900@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Eric W. Biederman