diff options
| author | Andy Lutomirski <[email protected]> | 2015-04-02 12:41:44 -0700 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2015-04-03 08:30:44 +0200 |
| commit | ff8287f36381deff729aa4e7b02296a080519fd0 (patch) | |
| tree | 0b59f060d0c1589edf8463bdad414592a3f1ef17 | |
| parent | d9dc64f30abe42f71bc7e9eb9d38c41006cf39f9 (diff) | |
x86/asm/entry/32: Improve a TOP_OF_KERNEL_STACK_PADDING comment
At Denys' request, clean up the comment describing stack padding
in the 32-bit sysenter path.
No code changes.
Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/41fee7bb8490ae840fe7ef2699f9c2feb932e729.1428002830.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/kernel/entry_32.S | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 4c8cc34e6d68..effa2793feba 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -395,10 +395,13 @@ sysenter_past_esp: /*CFI_REL_OFFSET cs, 0*/ /* * Push current_thread_info()->sysenter_return to the stack. - * A tiny bit of offset fixup is necessary - 4*4 means the 4 words - * pushed above; +8 corresponds to copy_thread's esp0 setting. + * A tiny bit of offset fixup is necessary: TI_sysenter_return + * is relative to thread_info, which is at the bottom of the + * kernel stack page. 4*4 means the 4 words pushed above; + * TOP_OF_KERNEL_STACK_PADDING takes us to the top of the stack; + * and THREAD_SIZE takes us to the bottom. */ - pushl_cfi ((TI_sysenter_return)-THREAD_SIZE+TOP_OF_KERNEL_STACK_PADDING+4*4)(%esp) + pushl_cfi ((TI_sysenter_return) - THREAD_SIZE + TOP_OF_KERNEL_STACK_PADDING + 4*4)(%esp) CFI_REL_OFFSET eip, 0 pushl_cfi %eax |