2023-06-12 22:16:37

by Andy Shevchenko

Subject: [PATCH v1 1/1] signal: Use %*ph for printing hexdump of a small buffer

The kernel already has a helper to print a hexdump of a small
buffer via pointer extension. Use that instead of open coded
variant.

In long term it helps to kill pr_cont() or at least narrow down
its use.

Signed-off-by: Andy Shevchenko <[email protected]>
---
kernel/signal.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index b5370fe5c198..6be2df76f0b4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1259,18 +1259,17 @@ static void print_fatal_signal(int signr)
pr_info("potentially unexpected fatal signal %d.\n", signr);

#if defined(__i386__) && !defined(__arch_um__)
- pr_info("code at %08lx: ", regs->ip);
{
+ unsigned char insn[16];
int i;
+
for (i = 0; i < 16; i++) {
- unsigned char insn;
-
- if (get_user(insn, (unsigned char *)(regs->ip + i)))
+ if (get_user(insn[i], (unsigned char __user *)(regs->ip + i)))
break;
- pr_cont("%02x ", insn);
}
+
+ pr_info("code at %08lx: %*ph\n", regs->ip, i, insn);
}
- pr_cont("\n");
#endif
preempt_disable();
show_regs(regs);
--
2.40.0.1.gaa8946217a0b

2023-06-13 13:36:49

by David Laight

Subject: RE: [PATCH v1 1/1] signal: Use %*ph for printing hexdump of a small buffer

From: Andy Shevchenko
> Sent: 12 June 2023 23:04
>
> The kernel already has a helper to print a hexdump of a small
> buffer via pointer extension. Use that instead of open coded
> variant.
>
> In long term it helps to kill pr_cont() or at least narrow down
> its use.
>
> Signed-off-by: Andy Shevchenko <[email protected]>
> ---
> kernel/signal.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index b5370fe5c198..6be2df76f0b4 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1259,18 +1259,17 @@ static void print_fatal_signal(int signr)
> pr_info("potentially unexpected fatal signal %d.\n", signr);
>
> #if defined(__i386__) && !defined(__arch_um__)
> - pr_info("code at %08lx: ", regs->ip);
> {
> + unsigned char insn[16];
> int i;
> +
> for (i = 0; i < 16; i++) {
> - unsigned char insn;
> -
> - if (get_user(insn, (unsigned char *)(regs->ip + i)))
> + if (get_user(insn[i], (unsigned char __user *)(regs->ip + i)))
> break;
> - pr_cont("%02x ", insn);
> }

Isn't that just:
i = 16 - copy_from_user(insn, (unsigned char __user *)regs->ip, 16);
(the 16 should be sizeof (insn))

David

> +
> + pr_info("code at %08lx: %*ph\n", regs->ip, i, insn);
> }
> - pr_cont("\n");
> #endif
> preempt_disable();
> show_regs(regs);
> --
> 2.40.0.1.gaa8946217a0b

-
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