From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zou Nan hai Date: Thu, 21 Sep 2006 07:13:28 +0000 Subject: Re: [PATCH] kprobe opcode 16 bytes alignment on IA64 Message-Id: <1158822808.2718.43.camel@linux-znh> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Thu, 2006-09-21 at 15:31, bibo,mao wrote: > Hi, > On IA64 instruction opcode must be 16 bytes alignment, in kprobe > structure there is one element to save original instruction, currently > saved opcode is not statically allocated in kprobe structure, that can > not assure 16 bytes alignment. This patch dynamically allocated kprobe > instruction opcode to assure 16 bytes alignment. > > signed-off-by: bibo mao > > thanks > bibo,mao > > diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c > index 781960f..e6cf5d4 100644 > --- a/arch/ia64/kernel/kprobes.c > +++ b/arch/ia64/kernel/kprobes.c > @@ -136,10 +136,8 @@ static void __kprobes update_kprobe_inst > static int __kprobes unsupported_inst(uint template, uint slot, > uint major_opcode, > unsigned long kprobe_inst, > - struct kprobe *p) > + unsigned long addr) > { > - unsigned long addr = (unsigned long)p->addr; > - > if (bundle_encoding[template][slot] = I) { > switch (major_opcode) { > case 0x0: //I_UNIT_MISC_OPCODE: > @@ -217,7 +215,7 @@ static void __kprobes prepare_break_inst > struct kprobe *p) > { > unsigned long break_inst = BREAK_INST; > - bundle_t *bundle = &p->ainsn.insn.bundle; > + bundle_t *bundle = &p->opcode.bundle; > > /* > * Copy the original kprobe_inst qualifying predicate(qp) > @@ -423,11 +421,9 @@ int __kprobes arch_prepare_kprobe(struct > unsigned long *kprobe_addr = (unsigned long *)(addr & > ~0xFULL); > unsigned long kprobe_inst=0; > unsigned int slot = addr & 0xf, template, major_opcode = 0; > - bundle_t *bundle = &p->ainsn.insn.bundle; > - > - memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t)); > - memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t)); > + bundle_t *bundle; > > + bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle; > template = bundle->quad0.template; > > if(valid_kprobe_addr(template, slot, addr)) > @@ -440,20 +436,19 @@ int __kprobes arch_prepare_kprobe(struct > /* Get kprobe_inst and major_opcode from the bundle */ > get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode); > > - if (unsupported_inst(template, slot, major_opcode, > kprobe_inst, p)) > + if (unsupported_inst(template, slot, major_opcode, > kprobe_inst, addr)) > return -EINVAL; > > - prepare_break_inst(template, slot, major_opcode, kprobe_inst, > p); > > - return 0; > -} > + p->ainsn.insn = get_insn_slot(); > + if (!p->ainsn.insn) > + return -ENOMEM; > + memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t)); > + memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t)); > > -void __kprobes flush_insn_slot(struct kprobe *p) > -{ > - unsigned long arm_addr; > + prepare_break_inst(template, slot, major_opcode, kprobe_inst, > p); > > - arm_addr = ((unsigned long)&p->opcode.bundle) & ~0xFULL; > - flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t)); > + return 0; > } > > void __kprobes arch_arm_kprobe(struct kprobe *p) > @@ -461,9 +456,10 @@ void __kprobes arch_arm_kprobe(struct kp > unsigned long addr = (unsigned long)p->addr; > unsigned long arm_addr = addr & ~0xFULL; > > - flush_insn_slot(p); > - memcpy((char *)arm_addr, &p->ainsn.insn.bundle, > sizeof(bundle_t)); > - flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t)); > + flush_icache_range((unsigned long)p->ainsn.insn, > + (unsigned long)p->ainsn.insn + > sizeof(kprobe_opcode_t)); > + memcpy((char *)arm_addr, &p->opcode, sizeof(kprobe_opcode_t)); > + flush_icache_range(arm_addr, arm_addr + > sizeof(kprobe_opcode_t)); > } > > void __kprobes arch_disarm_kprobe(struct kprobe *p) > @@ -471,11 +467,18 @@ void __kprobes arch_disarm_kprobe(struct > unsigned long addr = (unsigned long)p->addr; > unsigned long arm_addr = addr & ~0xFULL; > > - /* p->opcode contains the original unaltered bundle */ > - memcpy((char *) arm_addr, (char *) &p->opcode.bundle, > sizeof(bundle_t)); > - flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t)); > + /* p->ainsn.insn contains the original unaltered > kprobe_opcode_t */ > + memcpy((char *) arm_addr, (char *) p->ainsn.insn, > + sizeof(kprobe_opcode_t)); > + flush_icache_range(arm_addr, arm_addr + > sizeof(kprobe_opcode_t)); > } > > +void __kprobes arch_remove_kprobe(struct kprobe *p) > +{ > + mutex_lock(&kprobe_mutex); > + free_insn_slot(p->ainsn.insn); > + mutex_unlock(&kprobe_mutex); > +} > /* > * We are resuming execution after a single step fault, so the > pt_regs > * structure reflects the register state after we executed the > instruction > @@ -486,12 +489,12 @@ void __kprobes arch_disarm_kprobe(struct > */ > static void __kprobes resume_execution(struct kprobe *p, struct > pt_regs *regs) > { > - unsigned long bundle_addr = ((unsigned long) > (&p->opcode.bundle)) & ~0xFULL; > + unsigned long bundle_addr = (unsigned long) > (&p->ainsn.insn->bundle); > unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL; > unsigned long template; > int slot = ((unsigned long)p->addr & 0xf); > > - template = p->opcode.bundle.quad0.template; > + template = p->ainsn.insn->bundle.quad0.template; > > if (slot = 1 && bundle_encoding[template][1] = L) > slot = 2; > @@ -553,7 +556,7 @@ turn_ss_off: > > static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs > *regs) > { > - unsigned long bundle_addr = (unsigned long) &p->opcode.bundle; > + unsigned long bundle_addr = (unsigned long) > &p->ainsn.insn->bundle; > unsigned long slot = (unsigned long)p->addr & 0xf; > > /* single step inline if break instruction */ > diff --git a/include/asm-i386/kprobes.h b/include/asm-i386/kprobes.h > diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h > index 9389049..1b45b71 100644 > --- a/include/asm-ia64/kprobes.h > +++ b/include/asm-ia64/kprobes.h > @@ -29,7 +29,8 @@ #include > #include > #include > > -#define MAX_INSN_SIZE 16 > +#define __ARCH_WANT_KPROBES_INSN_SLOT > +#define MAX_INSN_SIZE 1 > #define BREAK_INST (long)(__IA64_BREAK_KPROBE << 6) > > typedef union cmp_inst { > @@ -94,7 +95,7 @@ #define IP_RELATIVE_BRANCH_OPCODE (4) > #define IP_RELATIVE_PREDICT_OPCODE (7) > #define LONG_BRANCH_OPCODE (0xC) > #define LONG_CALL_OPCODE (0xD) > -#define arch_remove_kprobe(p) do {} while (0) > +#define flush_insn_slot(p) do { } while (0) > > typedef struct kprobe_opcode { > bundle_t bundle; > @@ -108,7 +109,7 @@ struct fnptr { > /* Architecture specific copy of original instruction*/ > struct arch_specific_insn { > /* copy of the instruction to be emulated */ > - kprobe_opcode_t insn; > + kprobe_opcode_t *insn; > #define INST_FLAG_FIX_RELATIVE_IP_ADDR 1 > #define INST_FLAG_FIX_BRANCH_REG 2 > #define INST_FLAG_BREAK_INST 4 > @@ -125,6 +126,6 @@ static inline void jprobe_return(void) > } > extern void invalidate_stacked_regs(void); > extern void flush_register_stack(void); > -extern void flush_insn_slot(struct kprobe *p); > +extern void arch_remove_kprobe(struct kprobe *p); > > #endif /* _ASM_KPROBES_H */ > - I think it is DEBUG_SLAB that breaks the nature alignment of the kmalloced area. On a system without DEBUG_SLAB, ARCH_KMALLOC_MINALIGN is 128, and bundle_t is declared as __aligned__(16);. It is impossible to see insn aligned to a 8 byte boundary. But with DEBUG_SLAB enabled, ARCH_KMALLOC_MINALIGN may shrink to 8 bytes. Thanks Zou Nan hai > To unsubscribe from this list: send the line "unsubscribe linux-ia64" > in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >