Messages in this thread Patch in this message | | | From | Zheng Yejian <> | Subject | [PATCH v2] ftrace: Fix char print issue in print_ip_ins() | Date | Tue, 11 Oct 2022 12:03:52 +0000 |
| |
When ftrace bug happened, following log shows every hex data in problematic ip address: actual: ffffffe8:6b:ffffffd9:01:21
But so many 'f's seem a little confusing, and that is because format '%x' being used to print signed chars in array 'ins'. As suggested by Joe, change to use format "%*phC" to print array 'ins'.
After this patch, the log is like: actual: e8:6b:d9:01:21
Fixes: 6c14133d2d3f ("ftrace: Do not blindly read the ip address in ftrace_bug()") Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> --- kernel/trace/ftrace.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
Changes since v1: Use format "%*phC" to print array 'ins' as suggested by Joe. Link: https://lore.kernel.org/lkml/0a9453d94419991aa38d64b7a446eeba1f9c5a80.camel@perches.com/#t Usage of format "%*phC" can also be found in Documentation/core-api/printk-formats.rst "Raw buffer as a hex string"
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 447d2e2a8549..b838c717037a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2016,7 +2016,6 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, static void print_ip_ins(const char *fmt, const unsigned char *p) { char ins[MCOUNT_INSN_SIZE]; - int i; if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) { printk(KERN_CONT "%s[FAULT] %px\n", fmt, p); @@ -2024,9 +2023,7 @@ static void print_ip_ins(const char *fmt, const unsigned char *p) } printk(KERN_CONT "%s", fmt); - - for (i = 0; i < MCOUNT_INSN_SIZE; i++) - printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]); + pr_cont("%*phC", MCOUNT_INSN_SIZE, ins); } enum ftrace_bug_type ftrace_bug_type; -- 2.25.1
| |