From: Andi Kleen Date: Wed, 11 Jan 2006 21:45:21 +0000 (+0100) Subject: [PATCH] x86_64: Support alternative() in vsyscalls X-Git-Tag: v2.6.16-rc1~321 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f6c5b046978d68e69bdc73433ead41612a2a1c9;p=linux-2.6 [PATCH] x86_64: Support alternative() in vsyscalls The real vsyscall .text addresses are not mapped when the alternative() replacement runs early, so use some black magic to access them using the direct mapping. Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index e7a4d2cd39..8090a0a468 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -478,6 +478,8 @@ static unsigned char *k8_nops[ASM_NOP_MAX+1] = { k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, }; +extern char __vsyscall_0; + /* Replace instructions with better alternatives for this CPU type. This runs before SMP is initialized to avoid SMP problems with @@ -489,11 +491,17 @@ void apply_alternatives(void *start, void *end) struct alt_instr *a; int diff, i, k; for (a = start; (void *)a < end; a++) { + u8 *instr; + if (!boot_cpu_has(a->cpuid)) continue; BUG_ON(a->replacementlen > a->instrlen); - __inline_memcpy(a->instr, a->replacement, a->replacementlen); + instr = a->instr; + /* vsyscall code is not mapped yet. resolve it manually. */ + if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) + instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0)); + __inline_memcpy(instr, a->replacement, a->replacementlen); diff = a->instrlen - a->replacementlen; /* Pad the rest with nops */ @@ -501,7 +509,7 @@ void apply_alternatives(void *start, void *end) k = diff; if (k > ASM_NOP_MAX) k = ASM_NOP_MAX; - __inline_memcpy(a->instr + i, k8_nops[k], k); + __inline_memcpy(instr + i, k8_nops[k], k); } } }