Messages in this thread | | | Date | Thu, 14 Oct 2021 17:05:52 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 5/8] arm64: Recover kretprobe modified return address in stacktrace |
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On Wed, 13 Oct 2021 09:14:16 +0100 Will Deacon <will@kernel.org> wrote:
> On Fri, Oct 08, 2021 at 09:28:58PM +0900, Masami Hiramatsu wrote: > > Since the kretprobe replaces the function return address with > > the kretprobe_trampoline on the stack, stack unwinder shows it > > instead of the correct return address. > > > > This checks whether the next return address is the > > __kretprobe_trampoline(), and if so, try to find the correct > > return address from the kretprobe instance list. > > > > With this fix, now arm64 can enable > > CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE, and pass the > > kprobe self tests. > > > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > > --- > > arch/arm64/Kconfig | 1 + > > arch/arm64/include/asm/stacktrace.h | 2 ++ > > arch/arm64/kernel/stacktrace.c | 3 +++ > > 3 files changed, 6 insertions(+) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 5c7ae4c3954b..edde5171ffb2 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -11,6 +11,7 @@ config ARM64 > > select ACPI_PPTT if ACPI > > select ARCH_HAS_DEBUG_WX > > select ARCH_BINFMT_ELF_STATE > > + select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE > > select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION > > select ARCH_ENABLE_MEMORY_HOTPLUG > > select ARCH_ENABLE_MEMORY_HOTREMOVE > > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h > > index 8aebc00c1718..8f997a602651 100644 > > --- a/arch/arm64/include/asm/stacktrace.h > > +++ b/arch/arm64/include/asm/stacktrace.h > > @@ -9,6 +9,7 @@ > > #include <linux/sched.h> > > #include <linux/sched/task_stack.h> > > #include <linux/types.h> > > +#include <linux/llist.h> > > > > #include <asm/memory.h> > > #include <asm/ptrace.h> > > @@ -59,6 +60,7 @@ struct stackframe { > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > > int graph; > > #endif > > + struct llist_node *kr_cur; > > }; > > Please update the comment above this structure to describe the new member > you're adding.
OK, let me update that.
> If it's only relevant for kprobes, then let's define it > conditionally too (based on CONFIG_KRETPROBES ?)
Ah, good point! Yes, it must be only valid when CONFIG_KRETPROBES=y.
Thank you,
> > > extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); > > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > > index 8982a2b78acf..f1eef5745542 100644 > > --- a/arch/arm64/kernel/stacktrace.c > > +++ b/arch/arm64/kernel/stacktrace.c > > @@ -129,6 +129,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) > > frame->pc = ret_stack->ret; > > } > > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > > + if (is_kretprobe_trampoline(frame->pc)) > > + frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur); > > > > frame->pc = ptrauth_strip_insn_pac(frame->pc); > > > > @@ -224,6 +226,7 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > > { > > struct stackframe frame; > > > > + memset(&frame, 0, sizeof(frame)); > > Why do we need this? > > Will
-- Masami Hiramatsu <mhiramat@kernel.org>
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