From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Subject: [PATCH] nptl: x86_64: Use stackinfo.h definition for CURRENT_STACK_FRAME
Date: Mon, 29 Aug 2022 16:00:12 -0300 [thread overview]
Message-ID: <20220829190012.946402-1-adhemerval.zanella@linaro.org> (raw)
It avoids the possible warning of uninitialized 'frame' variable when
building with clang:
../sysdeps/nptl/jmp-unwind.c:27:42: error: variable 'frame' is
uninitialized when used here [-Werror,-Wuninitialized]
__pthread_cleanup_upto (env->__jmpbuf, CURRENT_STACK_FRAME);
It increases the generated code by one instruction:
--- master
+++ patch
@@ -25068,11 +25068,11 @@ Disassembly of section .text:
3db1b: 00 00
3db1d: 48 89 44 24 08 mov %rax,0x8(%rsp)
3db22: 31 c0 xor %eax,%eax
- 3db24: 48 8b 44 24 08 mov 0x8(%rsp),%rax
- 3db29: 64 48 2b 04 25 28 00 sub %fs:0x28,%rax
- 3db30: 00 00
- 3db32: 75 0c jne 3db40
<_longjmp_unwind+0x30>
- 3db34: 48 89 e6 mov %rsp,%rsi
+ 3db24: 48 89 e6 mov %rsp,%rsi
+ 3db27: 48 8b 44 24 08 mov 0x8(%rsp),%rax
+ 3db2c: 64 48 2b 04 25 28 00 sub %fs:0x28,%rax
+ 3db33: 00 00
+ 3db35: 75 09 jne 3db40
<_longjmp_unwind+0x30>
3db37: 48 83 c4 18 add $0x18,%rsp
3db3b: e9 60 31 05 00 jmp 90ca0
<__GI___pthread_cleanup_upto>
3db40: e8 4b ec 0e 00 call 12c790 <__stack_chk_fail>
Checked on x86_64-linux-gnu.
---
sysdeps/x86/nptl/pthreaddef.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sysdeps/x86/nptl/pthreaddef.h b/sysdeps/x86/nptl/pthreaddef.h
index 63fdbcb27c..3ff95efee6 100644
--- a/sysdeps/x86/nptl/pthreaddef.h
+++ b/sysdeps/x86/nptl/pthreaddef.h
@@ -42,7 +42,7 @@
#ifdef __x86_64__
/* The frame pointer is not usable. */
# define CURRENT_STACK_FRAME \
- ({ register char *frame __asm__("rsp"); frame; })
+ ({ void *p__; asm volatile ("mov %%" RSP_REG ", %0" : "=r" (p__)); p__; })
#else
# define CURRENT_STACK_FRAME __builtin_frame_address (0)
#endif
--
2.34.1
next reply other threads:[~2022-08-29 19:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-29 19:00 Adhemerval Zanella [this message]
2022-08-29 19:24 ` Noah Goldstein
2022-08-29 20:20 ` Adhemerval Zanella Netto
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