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49cd53bf14
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>
129 lines
3.1 KiB
C
129 lines
3.1 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1998, 1999, 2001, 2003 Ralf Baechle
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* Copyright (C) 2000, 2001 Silicon Graphics, Inc.
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*/
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#ifndef _UAPI_ASM_SIGINFO_H
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#define _UAPI_ASM_SIGINFO_H
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#define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
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#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ... */
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#define HAVE_ARCH_SIGINFO_T
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/*
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* Careful to keep union _sifields from shifting ...
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*/
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#if _MIPS_SZLONG == 32
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#define __ARCH_SI_PREAMBLE_SIZE (3 * sizeof(int))
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#elif _MIPS_SZLONG == 64
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#define __ARCH_SI_PREAMBLE_SIZE (4 * sizeof(int))
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#else
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#error _MIPS_SZLONG neither 32 nor 64
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#endif
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#define __ARCH_SIGSYS
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#include <uapi/asm-generic/siginfo.h>
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/* We can't use generic siginfo_t, because our si_code and si_errno are swapped */
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typedef struct siginfo {
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int si_signo;
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int si_code;
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int si_errno;
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int __pad0[SI_MAX_SIZE / sizeof(int) - SI_PAD_SIZE - 3];
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union {
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int _pad[SI_PAD_SIZE];
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/* kill() */
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struct {
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pid_t _pid; /* sender's pid */
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__ARCH_SI_UID_T _uid; /* sender's uid */
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} _kill;
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/* POSIX.1b timers */
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struct {
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timer_t _tid; /* timer id */
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int _overrun; /* overrun count */
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char _pad[sizeof( __ARCH_SI_UID_T) - sizeof(int)];
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sigval_t _sigval; /* same as below */
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int _sys_private; /* not to be passed to user */
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} _timer;
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/* POSIX.1b signals */
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struct {
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pid_t _pid; /* sender's pid */
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__ARCH_SI_UID_T _uid; /* sender's uid */
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sigval_t _sigval;
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} _rt;
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/* SIGCHLD */
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struct {
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pid_t _pid; /* which child */
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__ARCH_SI_UID_T _uid; /* sender's uid */
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int _status; /* exit code */
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clock_t _utime;
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clock_t _stime;
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} _sigchld;
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/* IRIX SIGCHLD */
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struct {
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pid_t _pid; /* which child */
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clock_t _utime;
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int _status; /* exit code */
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clock_t _stime;
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} _irix_sigchld;
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/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
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struct {
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void __user *_addr; /* faulting insn/memory ref. */
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#ifdef __ARCH_SI_TRAPNO
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int _trapno; /* TRAP # which caused the signal */
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#endif
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short _addr_lsb;
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union {
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/* used when si_code=SEGV_BNDERR */
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struct {
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void __user *_lower;
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void __user *_upper;
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} _addr_bnd;
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/* used when si_code=SEGV_PKUERR */
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__u32 _pkey;
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};
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} _sigfault;
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/* SIGPOLL, SIGXFSZ (To do ...) */
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struct {
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__ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */
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int _fd;
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} _sigpoll;
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/* SIGSYS */
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struct {
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void __user *_call_addr; /* calling user insn */
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int _syscall; /* triggering system call number */
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unsigned int _arch; /* AUDIT_ARCH_* of syscall */
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} _sigsys;
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} _sifields;
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} siginfo_t;
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/*
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* si_code values
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* Again these have been chosen to be IRIX compatible.
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*/
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#undef SI_ASYNCIO
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#undef SI_TIMER
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#undef SI_MESGQ
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#define SI_ASYNCIO -2 /* sent by AIO completion */
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#define SI_TIMER __SI_CODE(__SI_TIMER, -3) /* sent by timer expiration */
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#define SI_MESGQ __SI_CODE(__SI_MESGQ, -4) /* sent by real time mesq state change */
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#include <asm-generic/siginfo.h>
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#endif /* _UAPI_ASM_SIGINFO_H */
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