Messages in this thread Patch in this message | | | From | Tiezhu Yang <> | Subject | [PATCH 2/4] LoongArch: Add kretprobe support | Date | Tue, 20 Sep 2022 11:37:12 +0800 |
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Use the generic kretprobe trampoline handler to add kretprobe support for LoongArch.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> --- arch/loongarch/Kconfig | 1 + arch/loongarch/kernel/kprobes.c | 49 ++++++++++++++++++++++++++++++++++++++++- 2 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 6b01073..5f8503a 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -95,6 +95,7 @@ config LOONGARCH select HAVE_IRQ_EXIT_ON_IRQ_STACK select HAVE_IRQ_TIME_ACCOUNTING select HAVE_KPROBES + select HAVE_KRETPROBES select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI select HAVE_PCI diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c index b2c73a5..8c3efe5 100644 --- a/arch/loongarch/kernel/kprobes.c +++ b/arch/loongarch/kernel/kprobes.c @@ -303,7 +303,54 @@ int kprobe_exceptions_notify(struct notifier_block *self, } NOKPROBE_SYMBOL(kprobe_exceptions_notify); +/* + * 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. + */ +static void __used kretprobe_trampoline_holder(void) +{ + asm volatile(".global __kretprobe_trampoline\n" + "__kretprobe_trampoline:\n" + "nop\n"); +} + +/* Called when the probe at kretprobe trampoline is hit */ +static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) +{ + instruction_pointer(regs) = __kretprobe_trampoline_handler(regs, NULL); + /* + * By returning a non-zero value, we are telling + * kprobe_handler() that we don't want the post_handler + * to run (and have re-enabled preemption) + */ + return 1; +} +NOKPROBE_SYMBOL(trampoline_probe_handler); + +static struct kprobe trampoline_p = { + .addr = (kprobe_opcode_t *)__kretprobe_trampoline, + .pre_handler = trampoline_probe_handler +}; + +void arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->regs[1]; + ri->fp = NULL; + + /* Replace the return addr with trampoline addr */ + regs->regs[1] = (unsigned long)__kretprobe_trampoline; +} +NOKPROBE_SYMBOL(arch_prepare_kretprobe); + +int arch_trampoline_kprobe(struct kprobe *p) +{ + return p->addr == trampoline_p.addr; +} +NOKPROBE_SYMBOL(arch_trampoline_kprobe); + int __init arch_init_kprobes(void) { - return 0; + return register_kprobe(&trampoline_p); } -- 2.1.0
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