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/kernel/process.c | |
| 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/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 6f428da53e2..96d2fdf3aa9 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 |