diff mbox series

[v7,12/17] arm64: unwind: strip PAC from kernel addresses

Message ID 1584090304-18043-13-git-send-email-amit.kachhap@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: return address signing | expand

Commit Message

Amit Daniel Kachhap March 13, 2020, 9:04 a.m. UTC 
From: Mark Rutland <mark.rutland@arm.com>

When we enable pointer authentication in the kernel, LR values saved to
the stack will have a PAC which we must strip in order to retrieve the
real return address.

Strip PACs when unwinding the stack in order to account for this.

When function graph tracer is used with patchable-function-entry then
return_to_handler will also have pac bits so strip it too.

Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-position ptrauth_strip_insn_pac, comment]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v6:
 * Mask PAC bits of return_to_handler in case of FUNCTION_GRAPH_TRACER.

   incase 
 arch/arm64/kernel/stacktrace.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index a336cb1..139679c 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -14,6 +14,7 @@ 
 #include <linux/stacktrace.h>
 
 #include <asm/irq.h>
+#include <asm/pointer_auth.h>
 #include <asm/stack_pointer.h>
 #include <asm/stacktrace.h>
 
@@ -86,7 +87,7 @@  int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (tsk->ret_stack &&
-			(frame->pc == (unsigned long)return_to_handler)) {
+		(ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) {
 		struct ftrace_ret_stack *ret_stack;
 		/*
 		 * This is a case where function graph tracer has
@@ -101,6 +102,8 @@  int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 	}
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
+	frame->pc = ptrauth_strip_insn_pac(frame->pc);
+
 	/*
 	 * Frames created upon entry from EL0 have NULL FP and PC values, so
 	 * don't bother reporting these. Frames created by __noreturn functions