From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Thu, 21 Oct 2021 09:55:09 +0900
Subject: arm64: Recover kretprobe modified return address in stacktrace
Patch-mainline: v5.16-rc1
Git-commit: cd9bc2c9258816dc934b300705076519d7375b81
References: jsc#PED-1377
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: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/stacktrace.h | 4 ++++
arch/arm64/kernel/stacktrace.c | 7 +++++++
3 files changed, 12 insertions(+)
--- 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
--- 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 +60,9 @@ 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);
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -41,6 +41,9 @@ void start_backtrace(struct stackframe *
#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_str
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);