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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-09-24 15:17:21 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-09-25 14:15:51 +1000
commitcbc9565ee82694dec31d8137dec975b83175183b (patch)
tree7740d7f8f0372e80c067ee2e867bb69ab7b15eec /arch/powerpc/lib/sstep.c
parent0366a1c70b89efed4f9d590216bb004a16effbed (diff)
downloadop-kernel-dev-cbc9565ee82694dec31d8137dec975b83175183b.zip
op-kernel-dev-cbc9565ee82694dec31d8137dec975b83175183b.tar.gz
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/sstep.c')
-rw-r--r--arch/powerpc/lib/sstep.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index a7ee978..b1faa15 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.
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