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/include/asm/processor.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'arch/powerpc/include/asm/processor.h') diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index e378cccfca5..ce4de5aed7b 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -149,8 +149,6 @@ typedef struct { struct thread_struct { unsigned long ksp; /* Kernel stack pointer */ - unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */ - #ifdef CONFIG_PPC64 unsigned long ksp_vsid; #endif @@ -162,6 +160,7 @@ struct thread_struct { #endif #ifdef CONFIG_PPC32 void *pgdir; /* root of page-table tree */ + unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */ #endif #ifdef CONFIG_PPC_ADV_DEBUG_REGS /* @@ -321,7 +320,6 @@ struct thread_struct { #else #define INIT_THREAD { \ .ksp = INIT_SP, \ - .ksp_limit = INIT_SP_LIMIT, \ .regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \ .fs = KERNEL_DS, \ .fpr = {{0}}, \ -- cgit v1.2.3-70-g09d2