diff options
Diffstat (limited to 'arch/i386/kernel/alternative.c')
| -rw-r--r-- | arch/i386/kernel/alternative.c | 40 |
1 files changed, 34 insertions, 6 deletions
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c index 0695be538de5..206ea2ca63cc 100644 --- a/arch/i386/kernel/alternative.c +++ b/arch/i386/kernel/alternative.c @@ -2,8 +2,12 @@ #include <linux/sched.h> #include <linux/spinlock.h> #include <linux/list.h> +#include <linux/kprobes.h> +#include <linux/mm.h> +#include <linux/vmalloc.h> #include <asm/alternative.h> #include <asm/sections.h> +#include <asm/pgtable.h> #ifdef CONFIG_HOTPLUG_CPU static int smp_alt_once; @@ -150,7 +154,7 @@ static void nop_out(void *insns, unsigned int len) unsigned int noplen = len; if (noplen > ASM_NOP_MAX) noplen = ASM_NOP_MAX; - memcpy(insns, noptable[noplen], noplen); + text_poke(insns, noptable[noplen], noplen); insns += noplen; len -= noplen; } @@ -202,7 +206,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end) continue; if (*ptr > text_end) continue; - **ptr = 0xf0; /* lock prefix */ + text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock prefix */ }; } @@ -360,10 +364,6 @@ void apply_paravirt(struct paravirt_patch_site *start, /* Pad the rest with nops */ nop_out(p->instr + used, p->len - used); } - - /* Sync to be conservative, in case we patched following - * instructions */ - sync_core(); } extern struct paravirt_patch_site __start_parainstructions[], __stop_parainstructions[]; @@ -406,3 +406,31 @@ void __init alternative_instructions(void) apply_paravirt(__parainstructions, __parainstructions_end); local_irq_restore(flags); } + +/* + * Warning: + * When you use this code to patch more than one byte of an instruction + * you need to make sure that other CPUs cannot execute this code in parallel. + * Also no thread must be currently preempted in the middle of these instructions. + * And on the local CPU you need to be protected again NMI or MCE handlers + * seeing an inconsistent instruction while you patch. + */ +void __kprobes text_poke(void *oaddr, unsigned char *opcode, int len) +{ + u8 *addr = oaddr; + if (!pte_write(*lookup_address((unsigned long)addr))) { + struct page *p[2] = { virt_to_page(addr), virt_to_page(addr+PAGE_SIZE) }; + addr = vmap(p, 2, VM_MAP, PAGE_KERNEL); + if (!addr) + return; + addr += ((unsigned long)oaddr) % PAGE_SIZE; + } + memcpy(addr, opcode, len); + sync_core(); + /* Not strictly needed, but can speed CPU recovery up. Ignore cross cacheline + case. */ + if (cpu_has_clflush) + asm("clflush (%0) " :: "r" (oaddr) : "memory"); + if (addr != oaddr) + vunmap(addr); +} |