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arm64: Recover kretprobe modified return address in stacktrace

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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>
This commit is contained in:
Masami Hiramatsu 2021-10-21 09:55:09 +09:00 committed by Steven Rostedt (VMware)
parent fc6d647638
commit cd9bc2c925
3 changed files with 12 additions and 0 deletions
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1
arch/arm64/Kconfig
View file

@ -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

4
arch/arm64/include/asm/stacktrace.h
View file

@ -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);

7
arch/arm64/kernel/stacktrace.c
View file

@ -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);