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0b6ad02b33
commit 494d65129e
Author: Michael Jeanson <mjeanson@efficios.com>
Date: Thu Aug 1 10:35:34 2024 -0400
nptl: Introduce <rseq-access.h> for RSEQ_* accessors
added things like
asm volatile ("movl %%fs:%P1(%q2),%0" \
: "=r" (__value) \
: "i" (offsetof (struct rseq_area, member)), \
"r" (__rseq_offset)); \
But this doesn't work for x32 when __rseq_offset is negative since the
address is computed as
FS + 32-bit to 64-bit zero extension of __rseq_offset
+ offsetof (struct rseq_area, member)
Cast __rseq_offset to long long int
"r" ((long long int) __rseq_offset)); \
to sign-extend 32-bit __rseq_offset to 64-bit. This is a no-op for x86-64
since x86-64 __rseq_offset is 64-bit. This fixes BZ #32543.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
78 lines
3.5 KiB
C
78 lines
3.5 KiB
C
/* RSEQ_* accessors. x86_64 version.
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Copyright (C) 2002-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Read member of the RSEQ area directly, with single-copy atomicity semantics. */
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#define RSEQ_GETMEM_ONCE(member) \
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({ __typeof (RSEQ_SELF()->member) __value; \
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_Static_assert (sizeof (__value) == 1 \
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|| sizeof (__value) == 4 \
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|| sizeof (__value) == 8, \
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"size of rseq data"); \
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if (sizeof (__value) == 1) \
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asm volatile ("movb %%fs:%P2(%q3),%b0" \
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: "=q" (__value) \
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: "0" (0), "i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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else if (sizeof (__value) == 4) \
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asm volatile ("movl %%fs:%P1(%q2),%0" \
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: "=r" (__value) \
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: "i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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else /* 8 */ \
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{ \
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asm volatile ("movq %%fs:%P1(%q2),%q0" \
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: "=r" (__value) \
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: "i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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} \
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__value; })
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/* Read member of the RSEQ area directly. */
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#define RSEQ_GETMEM(member) RSEQ_GETMEM_ONCE(member)
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/* Set member of the RSEQ area directly, with single-copy atomicity semantics. */
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#define RSEQ_SETMEM_ONCE(member, value) \
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({ \
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_Static_assert (sizeof (RSEQ_SELF()->member) == 1 \
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|| sizeof (RSEQ_SELF()->member) == 4 \
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|| sizeof (RSEQ_SELF()->member) == 8, \
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"size of rseq data"); \
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if (sizeof (RSEQ_SELF()->member) == 1) \
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asm volatile ("movb %b0,%%fs:%P1(%q2)" : \
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: "iq" (value), \
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"i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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else if (sizeof (RSEQ_SELF()->member) == 4) \
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asm volatile ("movl %0,%%fs:%P1(%q2)" : \
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: IMM_MODE (value), \
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"i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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else /* 8 */ \
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{ \
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/* Since movq takes a signed 32-bit immediate or a register source \
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operand, use "er" constraint for 32-bit signed integer constant \
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or register. */ \
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asm volatile ("movq %q0,%%fs:%P1(%q2)" : \
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: "er" ((uint64_t) cast_to_integer (value)), \
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"i" (offsetof (struct rseq_area, member)), \
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"r" ((long long int) __rseq_offset)); \
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}})
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/* Set member of the RSEQ area directly. */
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#define RSEQ_SETMEM(member, value) RSEQ_SETMEM_ONCE(member, value)
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