From ab144f5ec64c42218a555ec1dbde6b60cf2982d6 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 10 Aug 2007 22:31:03 +0200 Subject: i386: Make patching more robust, fix paravirt issue Commit 19d36ccdc34f5ed444f8a6af0cbfdb6790eb1177 "x86: Fix alternatives and kprobes to remap write-protected kernel text" uses code which is being patched for patching. In particular, paravirt_ops does patching in two stages: first it calls paravirt_ops.patch, then it fills any remaining instructions with nop_out(). nop_out calls text_poke() which calls lookup_address() which calls pgd_val() (aka paravirt_ops.pgd_val): that call site is one of the places we patch. If we always do patching as one single call to text_poke(), we only need make sure we're not patching the memcpy in text_poke itself. This means the prototype to paravirt_ops.patch needs to change, to marshal the new code into a buffer rather than patching in place as it does now. It also means all patching goes through text_poke(), which is known to be safe (apply_alternatives is also changed to make a single patch). AK: fix compilation on x86-64 (bad rusty!) AK: fix boot on x86-64 (sigh) AK: merged with other patches Signed-off-by: Rusty Russell Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/i386/kernel/paravirt.c | 52 ++++++++++++++++++++++----------------------- 1 file changed, 26 insertions(+), 26 deletions(-) (limited to 'arch/i386/kernel/paravirt.c') diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c index ea962c0667d5..739cfb207dd7 100644 --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -69,7 +69,8 @@ DEF_NATIVE(read_tsc, "rdtsc"); DEF_NATIVE(ud2a, "ud2a"); -static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len) +static unsigned native_patch(u8 type, u16 clobbers, void *ibuf, + unsigned long addr, unsigned len) { const unsigned char *start, *end; unsigned ret; @@ -90,7 +91,7 @@ static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len) #undef SITE patch_site: - ret = paravirt_patch_insns(insns, len, start, end); + ret = paravirt_patch_insns(ibuf, len, start, end); break; case PARAVIRT_PATCH(make_pgd): @@ -107,7 +108,7 @@ static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len) break; default: - ret = paravirt_patch_default(type, clobbers, insns, len); + ret = paravirt_patch_default(type, clobbers, ibuf, addr, len); break; } @@ -129,68 +130,67 @@ struct branch { u32 delta; } __attribute__((packed)); -unsigned paravirt_patch_call(void *target, u16 tgt_clobbers, - void *site, u16 site_clobbers, +unsigned paravirt_patch_call(void *insnbuf, + const void *target, u16 tgt_clobbers, + unsigned long addr, u16 site_clobbers, unsigned len) { - unsigned char *call = site; - unsigned long delta = (unsigned long)target - (unsigned long)(call+5); - struct branch b; + struct branch *b = insnbuf; + unsigned long delta = (unsigned long)target - (addr+5); if (tgt_clobbers & ~site_clobbers) return len; /* target would clobber too much for this site */ if (len < 5) return len; /* call too long for patch site */ - b.opcode = 0xe8; /* call */ - b.delta = delta; - BUILD_BUG_ON(sizeof(b) != 5); - text_poke(call, (unsigned char *)&b, 5); + b->opcode = 0xe8; /* call */ + b->delta = delta; + BUILD_BUG_ON(sizeof(*b) != 5); return 5; } -unsigned paravirt_patch_jmp(void *target, void *site, unsigned len) +unsigned paravirt_patch_jmp(const void *target, void *insnbuf, + unsigned long addr, unsigned len) { - unsigned char *jmp = site; - unsigned long delta = (unsigned long)target - (unsigned long)(jmp+5); - struct branch b; + struct branch *b = insnbuf; + unsigned long delta = (unsigned long)target - (addr+5); if (len < 5) return len; /* call too long for patch site */ - b.opcode = 0xe9; /* jmp */ - b.delta = delta; - text_poke(jmp, (unsigned char *)&b, 5); + b->opcode = 0xe9; /* jmp */ + b->delta = delta; return 5; } -unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len) +unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf, + unsigned long addr, unsigned len) { void *opfunc = *((void **)¶virt_ops + type); unsigned ret; if (opfunc == NULL) /* If there's no function, patch it with a ud2a (BUG) */ - ret = paravirt_patch_insns(site, len, start_ud2a, end_ud2a); + ret = paravirt_patch_insns(insnbuf, len, start_ud2a, end_ud2a); else if (opfunc == paravirt_nop) /* If the operation is a nop, then nop the callsite */ ret = paravirt_patch_nop(); else if (type == PARAVIRT_PATCH(iret) || type == PARAVIRT_PATCH(irq_enable_sysexit)) /* If operation requires a jmp, then jmp */ - ret = paravirt_patch_jmp(opfunc, site, len); + ret = paravirt_patch_jmp(opfunc, insnbuf, addr, len); else /* Otherwise call the function; assume target could clobber any caller-save reg */ - ret = paravirt_patch_call(opfunc, CLBR_ANY, - site, clobbers, len); + ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY, + addr, clobbers, len); return ret; } -unsigned paravirt_patch_insns(void *site, unsigned len, +unsigned paravirt_patch_insns(void *insnbuf, unsigned len, const char *start, const char *end) { unsigned insn_len = end - start; @@ -198,7 +198,7 @@ unsigned paravirt_patch_insns(void *site, unsigned len, if (insn_len > len || start == NULL) insn_len = len; else - memcpy(site, start, insn_len); + memcpy(insnbuf, start, insn_len); return insn_len; } -- cgit v1.2.3-59-g8ed1b