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 <bibo.mao@xxxxxxxxx>
>
> 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 <linux/ptrace.h>
> #include <linux/percpu.h>
> #include <asm/break.h>
>
> -#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
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