diff options
| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-24 15:17:21 +1000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-25 14:15:51 +1000 |
| commit | cbc9565ee82694dec31d8137dec975b83175183b (patch) | |
| tree | 7740d7f8f0372e80c067ee2e867bb69ab7b15eec /arch/powerpc/include | |
| parent | 0366a1c70b89efed4f9d590216bb004a16effbed (diff) | |
powerpc: Remove ksp_limit on ppc64
We've been keeping that field in thread_struct for a while, it contains
the "limit" of the current stack pointer and is meant to be used for
detecting stack overflows.
It has a few problems however:
- First, it was never actually *used* on 64-bit. Set and updated but
not actually exploited
- When switching stack to/from irq and softirq stacks, it's update
is racy unless we hard disable interrupts, which is costly. This
is fine on 32-bit as we don't soft-disable there but not on 64-bit.
Thus rather than fixing 2 in order to implement 1 in some hypothetical
future, let's remove the code completely from 64-bit. In order to avoid
a clutter of ifdef's, we remove the updates from C code completely
during interrupt stack switching, and instead maintain it from the
asm helper that is used to do the stack switching in the first place.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/processor.h | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index e378cccfca55..ce4de5aed7b5 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -149,8 +149,6 @@ typedef struct { struct thread_struct { unsigned long ksp; /* Kernel stack pointer */ - unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */ - #ifdef CONFIG_PPC64 unsigned long ksp_vsid; #endif @@ -162,6 +160,7 @@ struct thread_struct { #endif #ifdef CONFIG_PPC32 void *pgdir; /* root of page-table tree */ + unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */ #endif #ifdef CONFIG_PPC_ADV_DEBUG_REGS /* @@ -321,7 +320,6 @@ struct thread_struct { #else #define INIT_THREAD { \ .ksp = INIT_SP, \ - .ksp_limit = INIT_SP_LIMIT, \ .regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \ .fs = KERNEL_DS, \ .fpr = {{0}}, \ |