Messages in this thread Patch in this message | | | From | Song Shuai <> | Subject | [PATCH] riscv/ftrace: fix ftrace_modify_call bug | Date | Tue, 22 Nov 2022 15:54:40 +0800 |
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With this commit (riscv: ftrace: Reduce the detour code size to half) patched, ftrace bug occurred When hosting kprobe and function tracer at the same function.
Obviously, the variable caller in ftrace_modify_call was assigned by rec->ip with 4 offset failing the code replacing at function entry. And the caller should be assigned by rec->ip directly to indicate the function entry.
The following is the ftrace bug log.
``` [ 419.632855] 00000000f8776803: expected (ffe00297 1a4282e7) but got (1a8282e7 f0227179) [ 419.633390] ------------[ ftrace bug ]------------ [ 419.633553] ftrace failed to modify [ 419.633569] [<ffffffff802091cc>] kernel_read+0x0/0x52 [ 419.633863] actual: 97:02:e0:ff:e7:82:82:1a [ 419.634087] Updating ftrace call site to call a different ftrace function [ 419.634279] ftrace record flags: e0000002 [ 419.634487] (2) R [ 419.634487] expected tramp: ffffffff800093cc [ 419.634935] ------------[ cut here ]------------ ```
Signed-off-by: Song Shuai <suagrfillet@gmail.com> --- arch/riscv/kernel/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index 8c77f236fc71..61b24d767e2e 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -132,7 +132,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) { unsigned int call[2]; - unsigned long caller = rec->ip + 4; + unsigned long caller = rec->ip; int ret; make_call_t0(caller, old_addr, call); -- 2.20.1
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