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author | Guo Ren <guoren@linux.alibaba.com> | 2020-04-01 09:17:02 +0800 |
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committer | Guo Ren <guoren@linux.alibaba.com> | 2020-04-03 11:14:17 +0800 |
commit | 33e53ae1ce413a081254e686d9b27cc1b3585e2f (patch) | |
tree | dd6ddbf5a1707f1d0351143cedc00147a465abf4 /arch/csky/kernel/probes/ftrace.c | |
parent | 000591f1ca3312d9a29e15a9e3fe5c4171f75586 (diff) | |
download | linux-stable-33e53ae1ce413a081254e686d9b27cc1b3585e2f.tar.gz linux-stable-33e53ae1ce413a081254e686d9b27cc1b3585e2f.tar.bz2 linux-stable-33e53ae1ce413a081254e686d9b27cc1b3585e2f.zip |
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.c | 66 |
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; +} |