diff options
| -rw-r--r-- | arch/ppc64/kernel/kprobes.c | 26 | ||||
| -rw-r--r-- | arch/x86_64/kernel/kprobes.c | 113 | ||||
| -rw-r--r-- | include/asm-ia64/kprobes.h | 1 | ||||
| -rw-r--r-- | include/asm-ppc64/kprobes.h | 2 | ||||
| -rw-r--r-- | include/linux/kprobes.h | 2 | ||||
| -rw-r--r-- | kernel/kprobes.c | 101 |
6 files changed, 128 insertions, 117 deletions
diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c index 782ce3e..86cc549 100644 --- a/arch/ppc64/kernel/kprobes.c +++ b/arch/ppc64/kernel/kprobes.c @@ -36,6 +36,8 @@ #include <asm/kdebug.h> #include <asm/sstep.h> +static DECLARE_MUTEX(kprobe_mutex); + static struct kprobe *current_kprobe; static unsigned long kprobe_status, kprobe_saved_msr; static struct kprobe *kprobe_prev; @@ -54,6 +56,15 @@ int arch_prepare_kprobe(struct kprobe *p) printk("Cannot register a kprobe on rfid or mtmsrd\n"); ret = -EINVAL; } + + /* insn must be on a special executable page on ppc64 */ + if (!ret) { + up(&kprobe_mutex); + p->ainsn.insn = get_insn_slot(); + down(&kprobe_mutex); + if (!p->ainsn.insn) + ret = -ENOMEM; + } return ret; } @@ -79,16 +90,22 @@ void arch_disarm_kprobe(struct kprobe *p) void arch_remove_kprobe(struct kprobe *p) { + up(&kprobe_mutex); + free_insn_slot(p->ainsn.insn); + down(&kprobe_mutex); } static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { + kprobe_opcode_t insn = *p->ainsn.insn; + regs->msr |= MSR_SE; - /*single step inline if it a breakpoint instruction*/ - if (p->opcode == BREAKPOINT_INSTRUCTION) + + /* single step inline if it is a trap variant */ + if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn)) regs->nip = (unsigned long)p->addr; else - regs->nip = (unsigned long)&p->ainsn.insn; + regs->nip = (unsigned long)p->ainsn.insn; } static inline void save_previous_kprobe(void) @@ -205,9 +222,10 @@ no_kprobe: static void resume_execution(struct kprobe *p, struct pt_regs *regs) { int ret; + unsigned int insn = *p->ainsn.insn; regs->nip = (unsigned long)p->addr; - ret = emulate_step(regs, p->ainsn.insn[0]); + ret = emulate_step(regs, insn); if (ret == 0) regs->nip = (unsigned long)p->addr + 4; } diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index 4e680f8..6a1c883 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -38,7 +38,7 @@ #include <linux/string.h> #include <linux/slab.h> #include <linux/preempt.h> -#include <linux/moduleloader.h> + #include <asm/cacheflush.h> #include <asm/pgtable.h> #include <asm/kdebug.h> @@ -51,8 +51,6 @@ static struct kprobe *kprobe_prev; static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev; static struct pt_regs jprobe_saved_regs; static long *jprobe_saved_rsp; -static kprobe_opcode_t *get_insn_slot(void); -static void free_insn_slot(kprobe_opcode_t *slot); void jprobe_return_end(void); /* copy of the kernel stack at the probe fire time */ @@ -681,112 +679,3 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) } return 0; } - -/* - * kprobe->ainsn.insn points to the copy of the instruction to be single-stepped. - * By default on x86_64, pages we get from kmalloc or vmalloc are not - * executable. Single-stepping an instruction on such a page yields an - * oops. So instead of storing the instruction copies in their respective - * kprobe objects, we allocate a page, map it executable, and store all the - * instruction copies there. (We can allocate additional pages if somebody - * inserts a huge number of probes.) Each page can hold up to INSNS_PER_PAGE - * instruction slots, each of which is MAX_INSN_SIZE*sizeof(kprobe_opcode_t) - * bytes. - */ -#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE*sizeof(kprobe_opcode_t))) -struct kprobe_insn_page { - struct hlist_node hlist; - kprobe_opcode_t *insns; /* page of instruction slots */ - char slot_used[INSNS_PER_PAGE]; - int nused; -}; - -static struct hlist_head kprobe_insn_pages; - -/** - * get_insn_slot() - Find a slot on an executable page for an instruction. - * We allocate an executable page if there's no room on existing ones. - */ -static kprobe_opcode_t *get_insn_slot(void) -{ - struct kprobe_insn_page *kip; - struct hlist_node *pos; - - hlist_for_each(pos, &kprobe_insn_pages) { - kip = hlist_entry(pos, struct kprobe_insn_page, hlist); - if (kip->nused < INSNS_PER_PAGE) { - int i; - for (i = 0; i < INSNS_PER_PAGE; i++) { - if (!kip->slot_used[i]) { - kip->slot_used[i] = 1; - kip->nused++; - return kip->insns + (i*MAX_INSN_SIZE); - } - } - /* Surprise! No unused slots. Fix kip->nused. */ - kip->nused = INSNS_PER_PAGE; - } - } - - /* All out of space. Need to allocate a new page. Use slot 0.*/ - kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); - if (!kip) { - return NULL; - } - - /* - * For the %rip-relative displacement fixups to be doable, we - * need our instruction copy to be within +/- 2GB of any data it - * might access via %rip. That is, within 2GB of where the - * kernel image and loaded module images reside. So we allocate - * a page in the module loading area. - */ - kip->insns = module_alloc(PAGE_SIZE); - if (!kip->insns) { - kfree(kip); - return NULL; - } - INIT_HLIST_NODE(&kip->hlist); - hlist_add_head(&kip->hlist, &kprobe_insn_pages); - memset(kip->slot_used, 0, INSNS_PER_PAGE); - kip->slot_used[0] = 1; - kip->nused = 1; - return kip->insns; -} - -/** - * free_insn_slot() - Free instruction slot obtained from get_insn_slot(). - */ -static void free_insn_slot(kprobe_opcode_t *slot) -{ - struct kprobe_insn_page *kip; - struct hlist_node *pos; - - hlist_for_each(pos, &kprobe_insn_pages) { - kip = hlist_entry(pos, struct kprobe_insn_page, hlist); - if (kip->insns <= slot - && slot < kip->insns+(INSNS_PER_PAGE*MAX_INSN_SIZE)) { - int i = (slot - kip->insns) / MAX_INSN_SIZE; - kip->slot_used[i] = 0; - kip->nused--; - if (kip->nused == 0) { - /* - * Page is no longer in use. Free it unless - * it's the last one. We keep the last one - * so as not to have to set it up again the - * next time somebody inserts a probe. - */ - hlist_del(&kip->hlist); - if (hlist_empty(&kprobe_insn_pages)) { - INIT_HLIST_NODE(&kip->hlist); - hlist_add_head(&kip->hlist, - &kprobe_insn_pages); - } else { - module_free(NULL, kip->insns); - kfree(kip); - } - } - return; - } - } -} diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h index 7b70003..25d8b1e 100644 --- a/include/asm-ia64/kprobes.h +++ b/include/asm-ia64/kprobes.h @@ -28,6 +28,7 @@ #include <linux/ptrace.h> #include <asm/break.h> +#define MAX_INSN_SIZE 16 #define BREAK_INST (long)(__IA64_BREAK_KPROBE << 6) typedef union cmp_inst { diff --git a/include/asm-ppc64/kprobes.h b/include/asm-ppc64/kprobes.h index 19b468b..790cf7c 100644 --- a/include/asm-ppc64/kprobes.h +++ b/include/asm-ppc64/kprobes.h @@ -45,7 +45,7 @@ typedef unsigned int kprobe_opcode_t; /* Architecture specific copy of original instruction */ struct arch_specific_insn { /* copy of original instruction */ - kprobe_opcode_t insn[MAX_INSN_SIZE]; + kprobe_opcode_t *insn; }; #ifdef CONFIG_KPROBES diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 5e1a7b0..d304d45 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -177,6 +177,8 @@ extern void arch_arm_kprobe(struct kprobe *p); extern void arch_disarm_kprobe(struct kprobe *p); extern void arch_remove_kprobe(struct kprobe *p); extern void show_registers(struct pt_regs *regs); +extern kprobe_opcode_t *get_insn_slot(void); +extern void free_insn_slot(kprobe_opcode_t *slot); /* Get the kprobe at this addr (if any). Must have called lock_kprobes */ struct kprobe *get_kprobe(void *addr); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 334f374..6524252 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -36,6 +36,7 @@ #include <linux/hash.h> #include <linux/init.h> #include <linux/module.h> +#include <linux/moduleloader.h> #include <asm/cacheflush.h> #include <asm/errno.h> #include <asm/kdebug.h> @@ -50,6 +51,106 @@ unsigned int kprobe_cpu = NR_CPUS; static DEFINE_SPINLOCK(kprobe_lock); static struct kprobe *curr_kprobe; +/* + * kprobe->ainsn.insn points to the copy of the instruction to be + * single-stepped. x86_64, POWER4 and above have no-exec support and + * stepping on the instruction on a vmalloced/kmalloced/data page + * is a recipe for disaster + */ +#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) + +struct kprobe_insn_page { + struct hlist_node hlist; + kprobe_opcode_t *insns; /* Page of instruction slots */ + char slot_used[INSNS_PER_PAGE]; + int nused; +}; + +static struct hlist_head kprobe_insn_pages; + +/** + * get_insn_slot() - Find a slot on an executable page for an instruction. + * We allocate an executable page if there's no room on existing ones. + */ +kprobe_opcode_t *get_insn_slot(void) +{ + struct kprobe_insn_page *kip; + struct hlist_node *pos; + + hlist_for_each(pos, &kprobe_insn_pages) { + kip = hlist_entry(pos, struct kprobe_insn_page, hlist); + if (kip->nused < INSNS_PER_PAGE) { + int i; + for (i = 0; i < INSNS_PER_PAGE; i++) { + if (!kip->slot_used[i]) { + kip->slot_used[i] = 1; + kip->nused++; + return kip->insns + (i * MAX_INSN_SIZE); + } + } + /* Surprise! No unused slots. Fix kip->nused. */ + kip->nused = INSNS_PER_PAGE; + } + } + + /* All out of space. Need to allocate a new page. Use slot 0.*/ + kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); + if (!kip) { + return NULL; + } + + /* + * Use module_alloc so this page is within +/- 2GB of where the + * kernel image and loaded module images reside. This is required + * so x86_64 can correctly handle the %rip-relative fixups. + */ + kip->insns = module_alloc(PAGE_SIZE); + if (!kip->insns) { + kfree(kip); + return NULL; + } + INIT_HLIST_NODE(&kip->hlist); + hlist_add_head(&kip->hlist, &kprobe_insn_pages); + memset(kip->slot_used, 0, INSNS_PER_PAGE); + kip->slot_used[0] = 1; + kip->nused = 1; + return kip->insns; +} + +void free_insn_slot(kprobe_opcode_t *slot) +{ + struct kprobe_insn_page *kip; + struct hlist_node *pos; + + hlist_for_each(pos, &kprobe_insn_pages) { + kip = hlist_entry(pos, struct kprobe_insn_page, hlist); + if (kip->insns <= slot && + slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { + int i = (slot - kip->insns) / MAX_INSN_SIZE; + kip->slot_used[i] = 0; + kip->nused--; + if (kip->nused == 0) { + /* + * Page is no longer in use. Free it unless + * it's the last one. We keep the last one + * so as not to have to set it up again the + * next time somebody inserts a probe. + */ + hlist_del(&kip->hlist); + if (hlist_empty(&kprobe_insn_pages)) { + INIT_HLIST_NODE(&kip->hlist); + hlist_add_head(&kip->hlist, + &kprobe_insn_pages); + } else { + module_free(NULL, kip->insns); + kfree(kip); + } + } + return; + } + } +} + /* Locks kprobe: irqs must be disabled */ void lock_kprobes(void) { |
