On 25 September 2013 20:05, Steven Rostedt <rost...@goodmis.org> wrote: > On Wed, 25 Sep 2013 18:44:22 +0800 > Jiang Liu <liu...@gmail.com> wrote: >> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c >> index 8541c3a..50facfc 100644 >> --- a/arch/arm64/kernel/insn.c >> +++ b/arch/arm64/kernel/insn.c >> @@ -15,6 +15,8 @@ >> * along with this program. If not, see <http://www.gnu.org/licenses/>. >> */ >> #include <linux/kernel.h> >> +#include <linux/stop_machine.h> >> +#include <asm/cacheflush.h> >> #include <asm/insn.h> >> >> static int aarch64_insn_cls[] = { >> @@ -69,3 +71,65 @@ bool __kprobes aarch64_insn_hotpatch_safe(u32 old_insn, >> u32 new_insn) >> return __aarch64_insn_hotpatch_safe(old_insn) && >> __aarch64_insn_hotpatch_safe(new_insn); >> } >> + >> +struct aarch64_insn_patch { >> + void *text_addr; >> + u32 *new_insns; >> + int insn_cnt; >> +}; >> + >> +int __kprobes __aarch64_insn_patch_text(void *addr, u32 *insns, int cnt) >> +{ >> + int i; >> + u32 *tp = addr; >> + >> + /* instructions must be word aligned */ >> + if (cnt <= 0 || ((uintptr_t)addr & 0x3)) >> + return -EINVAL; > > On aarch64, are instructions always word aligned? If not, it should be > safe for stop machine to modify non word aligned instructions, but this > patch looks like it doesn't allow stop_machine() to do so. Steve,
Yes, aarch64 instructions must be word-aligned, else instruction fetch would generate Misaligned PC fault. Thanks, Sandeepa > > -- Steve > >> + >> + for (i = 0; i < cnt; i++) >> + tp[i] = insns[i]; >> + >> + flush_icache_range((uintptr_t)tp, (uintptr_t)tp + cnt * sizeof(u32)); >> + >> + return 0; >> +} >> + >> +static int __kprobes aarch64_insn_patch_text_cb(void *arg) >> +{ >> + struct aarch64_insn_patch *pp = arg; >> + >> + return __aarch64_insn_patch_text(pp->text_addr, pp->new_insns, >> + pp->insn_cnt); >> +} >> + >> +int __kprobes aarch64_insn_patch_text(void *addr, u32 *insns, int cnt) >> +{ >> + int ret; >> + bool safe = false; >> + >> + /* instructions must be word aligned */ >> + if (cnt <= 0 || ((uintptr_t)addr & 0x3)) >> + return -EINVAL; >> + >> + if (cnt == 1) >> + safe = aarch64_insn_hotpatch_safe(*(u32 *)addr, insns[0]); >> + >> + if (safe) { >> + ret = __aarch64_insn_patch_text(addr, insns, cnt); >> + } else { >> + struct aarch64_insn_patch patch = { >> + .text_addr = addr, >> + .new_insns = insns, >> + .insn_cnt = cnt, >> + }; >> + >> + /* >> + * Execute __aarch64_insn_patch_text() on every online CPU, >> + * which ensure serialization among all online CPUs. >> + */ >> + ret = stop_machine(aarch64_insn_patch_text_cb, &patch, NULL); >> + } >> + >> + return ret; >> +} > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/