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authorChris Smith <chris.smith@st.com>2008-09-05 17:15:39 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-09-08 10:35:05 +0900
commitd39f5450146ff39f66cfde9d5184420627d0ac51 (patch)
treef71bf54b0e633b5a0cf4ca9a72809ba26c813bda /arch/sh/kernel/kprobes.c
parentsh: remove unnecessary memset after alloc_bootmem_low_pages (diff)
downloadlinux-dev-d39f5450146ff39f66cfde9d5184420627d0ac51.tar.xz
linux-dev-d39f5450146ff39f66cfde9d5184420627d0ac51.zip
sh: Add kprobes support.
Initial support for kprobes/kretprobes for 32-bit SH platforms. [ General cleanup and some rework for the kretprobe hash lock. -- PFM ] Signed-off-by: Chris Smith <chris.smith@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to '')
-rw-r--r--arch/sh/kernel/kprobes.c568
1 files changed, 568 insertions, 0 deletions
diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
new file mode 100644
index 000000000000..c4f4a0923eb9
--- /dev/null
+++ b/arch/sh/kernel/kprobes.c
@@ -0,0 +1,568 @@
+/*
+ * Kernel probes (kprobes) for SuperH
+ *
+ * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
+ * Copyright (C) 2006 Lineo Solutions, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/preempt.h>
+#include <linux/kdebug.h>
+#include <asm/cacheflush.h>
+#include <asm/uaccess.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+static struct kprobe saved_current_opcode;
+static struct kprobe saved_next_opcode;
+static struct kprobe saved_next_opcode2;
+
+#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
+#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
+#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
+#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
+#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
+#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
+
+#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
+#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
+
+#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
+#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
+
+#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
+#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
+
+ if (OPCODE_RTE(opcode))
+ return -EFAULT; /* Bad breakpoint */
+
+ p->opcode = opcode;
+
+ return 0;
+}
+
+void __kprobes arch_copy_kprobe(struct kprobe *p)
+{
+ memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+ p->opcode = *p->addr;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ *p->addr = BREAKPOINT_INSTRUCTION;
+ flush_icache_range((unsigned long)p->addr,
+ (unsigned long)p->addr + sizeof(kprobe_opcode_t));
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ *p->addr = p->opcode;
+ flush_icache_range((unsigned long)p->addr,
+ (unsigned long)p->addr + sizeof(kprobe_opcode_t));
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+ if (*p->addr == BREAKPOINT_INSTRUCTION)
+ return 1;
+
+ return 0;
+}
+
+/**
+ * If an illegal slot instruction exception occurs for an address
+ * containing a kprobe, remove the probe.
+ *
+ * Returns 0 if the exception was handled successfully, 1 otherwise.
+ */
+int __kprobes kprobe_handle_illslot(unsigned long pc)
+{
+ struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
+
+ if (p != NULL) {
+ printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
+ (unsigned int)pc + 2);
+ unregister_kprobe(p);
+ return 0;
+ }
+
+ return 1;
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ if (saved_next_opcode.addr != 0x0) {
+ arch_disarm_kprobe(p);
+ arch_disarm_kprobe(&saved_next_opcode);
+ saved_next_opcode.addr = 0x0;
+ saved_next_opcode.opcode = 0x0;
+
+ if (saved_next_opcode2.addr != 0x0) {
+ arch_disarm_kprobe(&saved_next_opcode2);
+ saved_next_opcode2.addr = 0x0;
+ saved_next_opcode2.opcode = 0x0;
+ }
+ }
+}
+
+static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+}
+
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+}
+
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = p;
+}
+
+/*
+ * Singlestep is implemented by disabling the current kprobe and setting one
+ * on the next instruction, following branches. Two probes are set if the
+ * branch is conditional.
+ */
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+ kprobe_opcode_t *addr = NULL;
+ saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
+ addr = saved_current_opcode.addr;
+
+ if (p != NULL) {
+ arch_disarm_kprobe(p);
+
+ if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
+ unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
+ saved_next_opcode.addr =
+ (kprobe_opcode_t *) regs->regs[reg_nr];
+ } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
+ unsigned long disp = (p->opcode & 0x0FFF);
+ saved_next_opcode.addr =
+ (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+
+ } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
+ unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
+ saved_next_opcode.addr =
+ (kprobe_opcode_t *) (regs->pc + 4 +
+ regs->regs[reg_nr]);
+
+ } else if (OPCODE_RTS(p->opcode)) {
+ saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr;
+
+ } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
+ unsigned long disp = (p->opcode & 0x00FF);
+ /* case 1 */
+ saved_next_opcode.addr = p->addr + 1;
+ /* case 2 */
+ saved_next_opcode2.addr =
+ (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+ saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
+ arch_arm_kprobe(&saved_next_opcode2);
+
+ } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
+ unsigned long disp = (p->opcode & 0x00FF);
+ /* case 1 */
+ saved_next_opcode.addr = p->addr + 2;
+ /* case 2 */
+ saved_next_opcode2.addr =
+ (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+ saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
+ arch_arm_kprobe(&saved_next_opcode2);
+
+ } else {
+ saved_next_opcode.addr = p->addr + 1;
+ }
+
+ saved_next_opcode.opcode = *(saved_next_opcode.addr);
+ arch_arm_kprobe(&saved_next_opcode);
+ }
+}
+
+/* Called with kretprobe_lock held */
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ ri->ret_addr = (kprobe_opcode_t *) regs->pr;
+
+ /* Replace the return addr with trampoline addr */
+ regs->pr = (unsigned long)kretprobe_trampoline;
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ int ret = 0;
+ kprobe_opcode_t *addr = NULL;
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
+
+ addr = (kprobe_opcode_t *) (regs->pc);
+
+ /* Check we're not actually recursing */
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
+ *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+ goto no_kprobe;
+ }
+ /* We have reentered the kprobe_handler(), since
+ * another probe was hit while within the handler.
+ * We here save the original kprobes variables and
+ * just single step on the instruction of the new probe
+ * without calling any user handlers.
+ */
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kprobes_inc_nmissed_count(p);
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_REENTER;
+ return 1;
+ } else {
+ p = __get_cpu_var(current_kprobe);
+ if (p->break_handler && p->break_handler(p, regs)) {
+ goto ss_probe;
+ }
+ }
+ goto no_kprobe;
+ }
+
+ p = get_kprobe(addr);
+ if (!p) {
+ /* Not one of ours: let kernel handle it */
+ goto no_kprobe;
+ }
+
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+ if (p->pre_handler && p->pre_handler(p, regs))
+ /* handler has already set things up, so skip ss setup */
+ return 1;
+
+ ss_probe:
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+ no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+/*
+ * For function-return probes, init_kprobes() establishes a probepoint
+ * here. When a retprobed function returns, this probe is hit and
+ * trampoline_probe_handler() runs, calling the kretprobe's handler.
+ */
+void kretprobe_trampoline_holder(void)
+{
+ asm volatile ("kretprobe_trampoline: \n" "nop\n");
+}
+
+/*
+ * Called when we hit the probe point at kretprobe_trampoline
+ */
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri = NULL;
+ struct hlist_head *head, empty_rp;
+ struct hlist_node *node, *tmp;
+ unsigned long flags, orig_ret_address = 0;
+ unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+
+ INIT_HLIST_HEAD(&empty_rp);
+ kretprobe_hash_lock(current, &head, &flags);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because an multiple functions in the call path
+ * have a return probe installed on them, and/or more then one return
+ * return probe was registered for a target function.
+ *
+ * We can handle this because:
+ * - instances are always inserted at the head of the list
+ * - when multiple return probes are registered for the same
+ * function, the first instance's ret_addr will point to the
+ * real return address, and all the rest will point to
+ * kretprobe_trampoline
+ */
+ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler) {
+ __get_cpu_var(current_kprobe) = &ri->rp->kp;
+ ri->rp->handler(ri, regs);
+ __get_cpu_var(current_kprobe) = NULL;
+ }
+
+ orig_ret_address = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri, &empty_rp);
+
+ if (orig_ret_address != trampoline_address)
+ /*
+ * This is the real return address. Any other
+ * instances associated with this task are for
+ * other calls deeper on the call stack
+ */
+ break;
+ }
+
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
+
+ regs->pc = orig_ret_address;
+ kretprobe_hash_unlock(current, &flags);
+
+ preempt_enable_no_resched();
+
+ hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+ hlist_del(&ri->hlist);
+ kfree(ri);
+ }
+
+ return orig_ret_address;
+}
+
+static inline int post_kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ kprobe_opcode_t *addr = NULL;
+ struct kprobe *p = NULL;
+
+ if (!cur)
+ return 0;
+
+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ cur->post_handler(cur, regs, 0);
+ }
+
+ if (saved_next_opcode.addr != 0x0) {
+ arch_disarm_kprobe(&saved_next_opcode);
+ saved_next_opcode.addr = 0x0;
+ saved_next_opcode.opcode = 0x0;
+
+ addr = saved_current_opcode.addr;
+ saved_current_opcode.addr = 0x0;
+
+ p = get_kprobe(addr);
+ arch_arm_kprobe(p);
+
+ if (saved_next_opcode2.addr != 0x0) {
+ arch_disarm_kprobe(&saved_next_opcode2);
+ saved_next_opcode2.addr = 0x0;
+ saved_next_opcode2.opcode = 0x0;
+ }
+ }
+
+ /*Restore back the original saved kprobes variables and continue. */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
+ goto out;
+ }
+ reset_current_kprobe();
+
+ out:
+ preempt_enable_no_resched();
+
+ return 1;
+}
+
+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ const struct exception_table_entry *entry;
+
+ switch (kcb->kprobe_status) {
+ case KPROBE_HIT_SS:
+ case KPROBE_REENTER:
+ /*
+ * We are here because the instruction being single
+ * stepped caused a page fault. We reset the current
+ * kprobe, point the pc back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->pc = (unsigned long)cur->addr;
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else
+ reset_current_kprobe();
+ preempt_enable_no_resched();
+ break;
+ case KPROBE_HIT_ACTIVE:
+ case KPROBE_HIT_SSDONE:
+ /*
+ * We increment the nmissed count for accounting,
+ * we can also use npre/npostfault count for accounting
+ * these specific fault cases.
+ */
+ kprobes_inc_nmissed_count(cur);
+
+ /*
+ * We come here because instructions in the pre/post
+ * handler caused the page_fault, this could happen
+ * if handler tries to access user space by
+ * copy_from_user(), get_user() etc. Let the
+ * user-specified handler try to fix it first.
+ */
+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+ return 1;
+
+ /*
+ * In case the user-specified fault handler returned
+ * zero, try to fix up.
+ */
+ if ((entry = search_exception_tables(regs->pc)) != NULL) {
+ regs->pc = entry->fixup;
+ return 1;
+ }
+
+ /*
+ * fixup_exception() could not handle it,
+ * Let do_page_fault() fix it.
+ */
+ break;
+ default:
+ break;
+ }
+ return 0;
+}
+
+/*
+ * Wrapper routine to for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct kprobe *p = NULL;
+ struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+ kprobe_opcode_t *addr = NULL;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ addr = (kprobe_opcode_t *) (args->regs->pc);
+ if (val == DIE_TRAP) {
+ if (!kprobe_running()) {
+ if (kprobe_handler(args->regs)) {
+ ret = NOTIFY_STOP;
+ } else {
+ /* Not a kprobe trap */
+ force_sig(SIGTRAP, current);
+ }
+ } else {
+ p = get_kprobe(addr);
+ if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
+ (kcb->kprobe_status == KPROBE_REENTER)) {
+ if (post_kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ } else {
+ if (kprobe_handler(args->regs)) {
+ ret = NOTIFY_STOP;
+ } else {
+ p = __get_cpu_var(current_kprobe);
+ if (p->break_handler
+ && p->break_handler(p, args->regs))
+ ret = NOTIFY_STOP;
+ }
+ }
+ }
+ }
+
+ return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct jprobe *jp = container_of(p, struct jprobe, kp);
+ unsigned long addr;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ kcb->jprobe_saved_regs = *regs;
+ kcb->jprobe_saved_r15 = regs->regs[15];
+ addr = kcb->jprobe_saved_r15;
+
+ /*
+ * TBD: As Linus pointed out, gcc assumes that the callee
+ * owns the argument space and could overwrite it, e.g.
+ * tailcall optimization. So, to be absolutely safe
+ * we also save and restore enough stack bytes to cover
+ * the argument area.
+ */
+ memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
+ MIN_STACK_SIZE(addr));
+
+ regs->pc = (unsigned long)(jp->entry);
+
+ return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+ __asm("trapa #-1\n\t" "jprobe_return_end:\n\t" "nop\n\t");
+
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ u8 *addr = (u8 *) regs->pc;
+ unsigned long stack_addr = kcb->jprobe_saved_r15;
+
+ if ((addr >= (u8 *) jprobe_return)
+ && (addr <= (u8 *) jprobe_return_end)) {
+ *regs = kcb->jprobe_saved_regs;
+
+ memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
+ MIN_STACK_SIZE(stack_addr));
+
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+ }
+ return 0;
+}
+
+static struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+ saved_next_opcode.addr = 0x0;
+ saved_next_opcode.opcode = 0x0;
+
+ saved_current_opcode.addr = 0x0;
+ saved_current_opcode.opcode = 0x0;
+
+ saved_next_opcode2.addr = 0x0;
+ saved_next_opcode2.opcode = 0x0;
+
+ return register_kprobe(&trampoline_p);
+}