Commit cd9bc2c9 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

arm64: Recover kretprobe modified return address in stacktrace 



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. For this purpose
this adds 'kr_cur' loop cursor to memorize the current kretprobe
instance.

With this fix, now arm64 can enable
CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE, and pass the
kprobe self tests.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent fc6d6476

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/arm64/include/asm/stacktrace.h

+4 −0
Original line number Diff line number Diff line
@@ -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 +60,9 @@ struct stackframe { 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	int graph;

#endif

#ifdef CONFIG_KRETPROBES

	struct llist_node *kr_cur;

#endif

};



extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);

arch/arm64/kernel/stacktrace.c

+7 −0
Original line number Diff line number Diff line
@@ -41,6 +41,9 @@ void start_backtrace(struct stackframe *frame, unsigned long fp, 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	frame->graph = 0;

#endif

#ifdef CONFIG_KRETPROBES

	frame->kr_cur = NULL;

#endif



	/*

	 * Prime the first unwind.
@@ -129,6 +132,10 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) 
		frame->pc = ret_stack->ret;

	}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifdef CONFIG_KRETPROBES

	if (is_kretprobe_trampoline(frame->pc))

		frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur);

#endif



	frame->pc = ptrauth_strip_insn_pac(frame->pc);