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authorGuo Ren <guoren@linux.alibaba.com>2020-04-01 09:17:02 +0800
committerGuo Ren <guoren@linux.alibaba.com>2020-04-03 11:14:17 +0800
commit33e53ae1ce413a081254e686d9b27cc1b3585e2f (patch)
treedd6ddbf5a1707f1d0351143cedc00147a465abf4 /arch/csky/kernel/probes/ftrace.c
parent000591f1ca3312d9a29e15a9e3fe5c4171f75586 (diff)
downloadlinux-sh-33e53ae1ce413a081254e686d9b27cc1b3585e2f.tar.gz
csky: Add kprobes supported
This patch enable kprobes, kretprobes, ftrace interface. It utilized software breakpoint and single step debug exceptions, instructions simulation on csky. We use USR_BKPT replace origin instruction, and the kprobe handler prepares an excutable memory slot for out-of-line execution with a copy of the original instruction being probed. Most of instructions could be executed by single-step, but some instructions need origin pc value to execute and we need software simulate these instructions. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'arch/csky/kernel/probes/ftrace.c')
-rw-r--r--arch/csky/kernel/probes/ftrace.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/arch/csky/kernel/probes/ftrace.c b/arch/csky/kernel/probes/ftrace.c
new file mode 100644
index 000000000000..5264763d05be
--- /dev/null
+++ b/arch/csky/kernel/probes/ftrace.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kprobes.h>
+
+int arch_check_ftrace_location(struct kprobe *p)
+{
+ if (ftrace_location((unsigned long)p->addr))
+ p->flags |= KPROBE_FLAG_FTRACE;
+ return 0;
+}
+
+/* Ftrace callback handler for kprobes -- called under preepmt disabed */
+void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *ops, struct pt_regs *regs)
+{
+ bool lr_saver = false;
+ struct kprobe *p;
+ struct kprobe_ctlblk *kcb;
+
+ /* Preempt is disabled by ftrace */
+ p = get_kprobe((kprobe_opcode_t *)ip);
+ if (!p) {
+ p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
+ if (unlikely(!p) || kprobe_disabled(p))
+ return;
+ lr_saver = true;
+ }
+
+ kcb = get_kprobe_ctlblk();
+ if (kprobe_running()) {
+ kprobes_inc_nmissed_count(p);
+ } else {
+ unsigned long orig_ip = instruction_pointer(regs);
+
+ if (lr_saver)
+ ip -= MCOUNT_INSN_SIZE;
+ instruction_pointer_set(regs, ip);
+ __this_cpu_write(current_kprobe, p);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ if (!p->pre_handler || !p->pre_handler(p, regs)) {
+ /*
+ * Emulate singlestep (and also recover regs->pc)
+ * as if there is a nop
+ */
+ instruction_pointer_set(regs,
+ (unsigned long)p->addr + MCOUNT_INSN_SIZE);
+ if (unlikely(p->post_handler)) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ p->post_handler(p, regs, 0);
+ }
+ instruction_pointer_set(regs, orig_ip);
+ }
+ /*
+ * If pre_handler returns !0, it changes regs->pc. We have to
+ * skip emulating post_handler.
+ */
+ __this_cpu_write(current_kprobe, NULL);
+ }
+}
+NOKPROBE_SYMBOL(kprobe_ftrace_handler);
+
+int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+ p->ainsn.api.insn = NULL;
+ return 0;
+}