Messages in this thread | | | Date | Wed, 13 Oct 2021 09:14:16 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 5/8] arm64: Recover kretprobe modified return address in stacktrace |
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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. If it's only relevant for kprobes, then let's define it conditionally too (based on CONFIG_KRETPROBES ?)
> 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
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