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| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-24 09:17:21 +0400 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-25 08:15:51 +0400 |
| commit | cbc9565ee82694dec31d8137dec975b83175183b (patch) | |
| tree | 7740d7f8f0372e80c067ee2e867bb69ab7b15eec /arch/powerpc/lib | |
| parent | 0366a1c70b89efed4f9d590216bb004a16effbed (diff) | |
| download | linux-cbc9565ee82694dec31d8137dec975b83175183b.tar.xz | |
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/lib')
| -rw-r--r-- | arch/powerpc/lib/sstep.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index a7ee978fb860..b1faa1593c90 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1505,6 +1505,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) */ if ((ra == 1) && !(regs->msr & MSR_PR) \ && (val3 >= (regs->gpr[1] - STACK_INT_FRAME_SIZE))) { +#ifdef CONFIG_PPC32 /* * Check if we will touch kernel sack overflow */ @@ -1513,7 +1514,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) err = -EINVAL; break; } - +#endif /* CONFIG_PPC32 */ /* * Check if we already set since that means we'll * lose the previous value. |