diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2015-03-07 02:50:19 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-07 09:34:03 +0100 |
| commit | a7fcf28d431ef70afaa91496e64e16dc51dccec4 (patch) | |
| tree | 3de032435c43db84cdfc4f7e46df4d118b86fe82 /arch/x86/kernel/process_32.c | |
| parent | x86/asm/entry: Delay loading sp0 slightly on task switch (diff) | |
| download | linux-a7fcf28d431ef70afaa91496e64e16dc51dccec4.tar.xz linux-a7fcf28d431ef70afaa91496e64e16dc51dccec4.zip | |
x86/asm/entry: Replace this_cpu_sp0() with current_top_of_stack() and fix it on x86_32
I broke 32-bit kernels. The implementation of sp0 was correct
as far as I can tell, but sp0 was much weirder on x86_32 than I
realized. It has the following issues:
- Init's sp0 is inconsistent with everything else's: non-init tasks
are offset by 8 bytes. (I have no idea why, and the comment is unhelpful.)
- vm86 does crazy things to sp0.
Fix it up by replacing this_cpu_sp0() with
current_top_of_stack() and using a new percpu variable to track
the top of the stack on x86_32.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 75182b1632a8 ("x86/asm/entry: Switch all C consumers of kernel_stack to this_cpu_sp0()")
Link: http://lkml.kernel.org/r/d09dbe270883433776e0cbee3c7079433349e96d.1425692936.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/process_32.c')
| -rw-r--r-- | arch/x86/kernel/process_32.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 0405cab6634d..1b9963faf4eb 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -306,13 +306,16 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) arch_end_context_switch(next_p); /* - * Reload esp0. This changes current_thread_info(). + * Reload esp0, kernel_stack, and current_top_of_stack. This changes + * current_thread_info(). */ load_sp0(tss, next); - this_cpu_write(kernel_stack, - (unsigned long)task_stack_page(next_p) + - THREAD_SIZE - KERNEL_STACK_OFFSET); + (unsigned long)task_stack_page(next_p) + + THREAD_SIZE - KERNEL_STACK_OFFSET); + this_cpu_write(cpu_current_top_of_stack, + (unsigned long)task_stack_page(next_p) + + THREAD_SIZE); /* * Restore %gs if needed (which is common) |