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Message-Id: <1674007261-9198-5-git-send-email-yangtiezhu@loongson.cn>
Date: Wed, 18 Jan 2023 10:01:00 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Masami Hiramatsu <mhiramat@...nel.org>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v12 4/5] LoongArch: Mark some assembler symbols as non-kprobe-able
Some assembler symbols are not kprobe safe, such as handle_syscall
(used as syscall exception handler), *memcpy* (may cause recursive
exceptions), they can not be instrumented, just blacklist them for
kprobing.
Here is a related problem and discussion:
Link: https://lore.kernel.org/lkml/20230114143859.7ccc45c1c5d9ce302113ab0a@kernel.org/
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
arch/loongarch/include/asm/asm.h | 10 ++++++++++
arch/loongarch/kernel/entry.S | 1 +
arch/loongarch/lib/memcpy.S | 3 +++
3 files changed, 14 insertions(+)
diff --git a/arch/loongarch/include/asm/asm.h b/arch/loongarch/include/asm/asm.h
index 40eea6a..f591b32 100644
--- a/arch/loongarch/include/asm/asm.h
+++ b/arch/loongarch/include/asm/asm.h
@@ -188,4 +188,14 @@
#define PTRLOG 3
#endif
+/* Annotate a function as being unsuitable for kprobes. */
+#ifdef CONFIG_KPROBES
+#define _ASM_NOKPROBE(name) \
+ .pushsection "_kprobe_blacklist", "aw"; \
+ .quad name; \
+ .popsection
+#else
+#define _ASM_NOKPROBE(name)
+#endif
+
#endif /* __ASM_ASM_H */
diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
index d53b631..55e23b1 100644
--- a/arch/loongarch/kernel/entry.S
+++ b/arch/loongarch/kernel/entry.S
@@ -67,6 +67,7 @@ SYM_FUNC_START(handle_syscall)
RESTORE_ALL_AND_RET
SYM_FUNC_END(handle_syscall)
+_ASM_NOKPROBE(handle_syscall)
SYM_CODE_START(ret_from_fork)
bl schedule_tail # a0 = struct task_struct *prev
diff --git a/arch/loongarch/lib/memcpy.S b/arch/loongarch/lib/memcpy.S
index 7c07d59..3b7e1de 100644
--- a/arch/loongarch/lib/memcpy.S
+++ b/arch/loongarch/lib/memcpy.S
@@ -17,6 +17,7 @@ SYM_FUNC_START(memcpy)
ALTERNATIVE "b __memcpy_generic", \
"b __memcpy_fast", CPU_FEATURE_UAL
SYM_FUNC_END(memcpy)
+_ASM_NOKPROBE(memcpy)
EXPORT_SYMBOL(memcpy)
@@ -41,6 +42,7 @@ SYM_FUNC_START(__memcpy_generic)
2: move a0, a3
jr ra
SYM_FUNC_END(__memcpy_generic)
+_ASM_NOKPROBE(__memcpy_generic)
/*
* void *__memcpy_fast(void *dst, const void *src, size_t n)
@@ -93,3 +95,4 @@ SYM_FUNC_START(__memcpy_fast)
3: move a0, a3
jr ra
SYM_FUNC_END(__memcpy_fast)
+_ASM_NOKPROBE(__memcpy_fast)
--
2.1.0
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