From cbc9565ee82694dec31d8137dec975b83175183b Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Tue, 24 Sep 2013 15:17:21 +1000 Subject: 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 --- arch/powerpc/lib/sstep.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/lib') 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. -- cgit v1.2.3