This is a note to let you know that I've just added the patch titled
riscv: blacklist assembly symbols for kprobe
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-blacklist-assembly-symbols-for-kprobe.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1e6fd6730bc923dbc510243b51f17eb93e2d670e
Author: Clément Léger <cleger@xxxxxxxxxxxx>
Date: Wed Oct 4 15:10:09 2023 +0200
riscv: blacklist assembly symbols for kprobe
[ Upstream commit 5014396af9bbac0f28d9afee7eae405206d01ee7 ]
Adding kprobes on some assembly functions (mainly exception handling)
will result in crashes (either recursive trap or panic). To avoid such
errors, add ASM_NOKPROBE() macro which allow adding specific symbols
into the __kprobe_blacklist section and use to blacklist the following
symbols that showed to be problematic:
- handle_exception()
- ret_from_exception()
- handle_kernel_stack_overflow()
Signed-off-by: Clément Léger <cleger@xxxxxxxxxxxx>
Reviewed-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231004131009.409193-1-cleger@xxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h
index bfb4c26f113c4..b5b84c6be01e1 100644
--- a/arch/riscv/include/asm/asm.h
+++ b/arch/riscv/include/asm/asm.h
@@ -164,6 +164,16 @@
REG_L x31, PT_T6(sp)
.endm
+/* Annotate a function as being unsuitable for kprobes. */
+#ifdef CONFIG_KPROBES
+#define ASM_NOKPROBE(name) \
+ .pushsection "_kprobe_blacklist", "aw"; \
+ RISCV_PTR name; \
+ .popsection
+#else
+#define ASM_NOKPROBE(name)
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_RISCV_ASM_H */
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 278d01d2911fd..ed7baf2cf7e87 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -105,6 +105,7 @@ _save_context:
1:
tail do_trap_unknown
SYM_CODE_END(handle_exception)
+ASM_NOKPROBE(handle_exception)
/*
* The ret_from_exception must be called with interrupt disabled. Here is the
@@ -171,6 +172,7 @@ SYM_CODE_START_NOALIGN(ret_from_exception)
sret
#endif
SYM_CODE_END(ret_from_exception)
+ASM_NOKPROBE(ret_from_exception)
#ifdef CONFIG_VMAP_STACK
SYM_CODE_START_LOCAL(handle_kernel_stack_overflow)
@@ -206,6 +208,7 @@ SYM_CODE_START_LOCAL(handle_kernel_stack_overflow)
move a0, sp
tail handle_bad_stack
SYM_CODE_END(handle_kernel_stack_overflow)
+ASM_NOKPROBE(handle_kernel_stack_overflow)
#endif
SYM_CODE_START(ret_from_fork)
