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@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20231004131009.409193-1-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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 */
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
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)
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)