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| author | Markus F.X.J. Oberhumer <markus@oberhumer.com> | 2005-10-09 18:54:23 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-10 08:45:06 -0700 |
| commit | d347f372273c2b3d86a66e2e1c94c790c208e166 (patch) | |
| tree | 2015798f0acdc66866765438343f992326db51ad | |
| parent | 867f8b4e47a17c5d68c98dc6eee12739c4490056 (diff) | |
| download | linux-d347f372273c2b3d86a66e2e1c94c790c208e166.tar.bz2 | |
[PATCH] i386: fix stack alignment for signal handlers
This fixes the setup of the alignment of the signal frame, so that all
signal handlers are run with a properly aligned stack frame.
The current code "over-aligns" the stack pointer so that the stack frame
is effectively always mis-aligned by 4 bytes. But what we really want
is that on function entry ((sp + 4) & 15) == 0, which matches what would
happen if the stack were aligned before a "call" instruction.
Signed-off-by: Markus F.X.J. Oberhumer <markus@oberhumer.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | arch/i386/kernel/signal.c | 6 | ||||
| -rw-r--r-- | arch/x86_64/ia32/ia32_signal.c | 6 |
2 files changed, 10 insertions, 2 deletions
diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c index 61eb0c8a6e47..adcd069db91e 100644 --- a/arch/i386/kernel/signal.c +++ b/arch/i386/kernel/signal.c @@ -338,7 +338,11 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) esp = (unsigned long) ka->sa.sa_restorer; } - return (void __user *)((esp - frame_size) & -8ul); + esp -= frame_size; + /* Align the stack pointer according to the i386 ABI, + * i.e. so that on function entry ((sp + 4) & 15) == 0. */ + esp = ((esp + 4) & -16ul) - 4; + return (void __user *) esp; } /* These symbols are defined with the addresses in the vsyscall page. diff --git a/arch/x86_64/ia32/ia32_signal.c b/arch/x86_64/ia32/ia32_signal.c index 66e2821533db..0903cc1faef2 100644 --- a/arch/x86_64/ia32/ia32_signal.c +++ b/arch/x86_64/ia32/ia32_signal.c @@ -425,7 +425,11 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) rsp = (unsigned long) ka->sa.sa_restorer; } - return (void __user *)((rsp - frame_size) & -8UL); + rsp -= frame_size; + /* Align the stack pointer according to the i386 ABI, + * i.e. so that on function entry ((sp + 4) & 15) == 0. */ + rsp = ((rsp + 4) & -16ul) - 4; + return (void __user *) rsp; } int ia32_setup_frame(int sig, struct k_sigaction *ka, |