lkml.org 
[lkml]   [2022]   [Oct]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] ftrace: Fix char print issue in print_ip_ins()
From
Date
On Mon, 2022-10-10 at 19:15 +0000, Zheng Yejian wrote:
> When ftrace bug happened, following log shows every byte data in
> problem ip address:
> actual: ffffffe8:6b:ffffffd9:01:21
>
> However that seems a little confusing, and it is because format
> '%x' being used to print signed chars in print_ip_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()")
> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
> ---
> kernel/trace/ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
[]
> @@ -2015,7 +2015,7 @@ 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];
> + unsigned char ins[MCOUNT_INSN_SIZE];
> int i;
>
> if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) {

Perhaps nicer would be to change the for loop below this from

for (i = 0; i < MCOUNT_INSN_SIZE; i++)
printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]);

to

pr_cont("%*phC", MCOUNT_INSN_SIZE, ins);

\
 
 \ /
  Last update: 2022-10-11 04:36    [W:0.094 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site