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x86_64: Use __seg_fs qualifier to cast access to TCB in THREAD_GSCOPE_RESET_FLAG() 

Use the __seg_fs named address space qualifier to cast access to the
gscope_flag in the TCB as a %fs: prefixed address.  This enables the
use of the "m" operand constraint, which informs the compiler about
memory access in the inline assembly.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: H.J.Lu <hjl.tools@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Uros Bizjak 2025-09-10 20:30:56 +02:00
parent 273f80374a
commit 3628351bcd
1 changed files with 3 additions and 2 deletions
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5
sysdeps/x86_64/nptl/tls.h
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@ -201,9 +201,10 @@ _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
# define THREAD_GSCOPE_RESET_FLAG() \
do \
{ int __res; \
asm volatile ("xchgl %0, %%fs:%P1" \
asm volatile ("xchgl %1, %0" \
: "=r" (__res) \
: "i" (offsetof (struct pthread, header.gscope_flag)), \
: "m" (*(int __seg_fs *) \
offsetof (struct pthread, header.gscope_flag)), \
"0" (THREAD_GSCOPE_FLAG_UNUSED)); \
if (__res == THREAD_GSCOPE_FLAG_WAIT) \
lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \