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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/kernel/process.c
parent0366a1c70b89efed4f9d590216bb004a16effbed (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/kernel/process.c')
-rw-r--r--arch/powerpc/kernel/process.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 6f428da53e20..96d2fdf3aa9e 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1000,9 +1000,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
kregs = (struct pt_regs *) sp;
sp -= STACK_FRAME_OVERHEAD;
p->thread.ksp = sp;
+#ifdef CONFIG_PPC32
p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
_ALIGN_UP(sizeof(struct thread_info), 16);
-
+#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
p->thread.ptrace_bps[0] = NULL;
#endif