2022-04-25 13:25:56

by Stephen Zhang

Subject: [PATCH] x86/traps: add CONFIG_BUG to the use of __warn()

From: zhangshida <[email protected]>

__warn() is declared when CONFIG_BUG is defined, so add
CONFIG_BUG when used.

Signed-off-by: zhangshida <[email protected]>
---
arch/x86/kernel/traps.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1563fb995005..81cc28a59c24 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -246,7 +246,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
pr_err("Missing ENDBR: %pS\n", (void *)instruction_pointer(regs));
if (!ibt_fatal) {
printk(KERN_DEFAULT CUT_HERE);
+#ifdef CONFIG_BUG
__warn(__FILE__, __LINE__, (void *)regs->ip, TAINT_WARN, regs, NULL);
+#endif
return;
}
BUG();
--
2.25.1

2022-04-26 02:46:53

by Dave Hansen

Subject: Re: [PATCH] x86/traps: add CONFIG_BUG to the use of __warn()

On 4/24/22 22:59, Stephen Zhang wrote:
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -246,7 +246,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
> pr_err("Missing ENDBR: %pS\n", (void *)instruction_pointer(regs));
> if (!ibt_fatal) {
> printk(KERN_DEFAULT CUT_HERE);
> +#ifdef CONFIG_BUG
> __warn(__FILE__, __LINE__, (void *)regs->ip, TAINT_WARN, regs, NULL);
> +#endif

This really should be done with an #ifdef'd stub in in bug.h, not an
#ifdef at every call site. I assume there was a good reason for not
using the normal WARN*() macros.

2022-04-26 04:29:59

by Peter Zijlstra

Subject: Re: [PATCH] x86/traps: add CONFIG_BUG to the use of __warn()

On Mon, Apr 25, 2022 at 09:05:17AM -0700, Dave Hansen wrote:
> On 4/24/22 22:59, Stephen Zhang wrote:
> > --- a/arch/x86/kernel/traps.c
> > +++ b/arch/x86/kernel/traps.c
> > @@ -246,7 +246,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
> > pr_err("Missing ENDBR: %pS\n", (void *)instruction_pointer(regs));
> > if (!ibt_fatal) {
> > printk(KERN_DEFAULT CUT_HERE);
> > +#ifdef CONFIG_BUG
> > __warn(__FILE__, __LINE__, (void *)regs->ip, TAINT_WARN, regs, NULL);
> > +#endif
>
> This really should be done with an #ifdef'd stub in in bug.h, not an
> #ifdef at every call site. I assume there was a good reason for not
> using the normal WARN*() macros.

I think the idea was to have the pr_err() unconditional, and if you have
the fancy crap on also print a full backtrace or something.

But yeah, a few stubs in bug.h ought to make this go away too.

2022-04-26 08:43:55

by Peter Zijlstra

Subject: Re: [PATCH] x86/traps: add CONFIG_BUG to the use of __warn()

On Mon, Apr 25, 2022 at 08:24:56PM +0200, Peter Zijlstra wrote:
> On Mon, Apr 25, 2022 at 09:05:17AM -0700, Dave Hansen wrote:
> > On 4/24/22 22:59, Stephen Zhang wrote:
> > > --- a/arch/x86/kernel/traps.c
> > > +++ b/arch/x86/kernel/traps.c
> > > @@ -246,7 +246,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
> > > pr_err("Missing ENDBR: %pS\n", (void *)instruction_pointer(regs));
> > > if (!ibt_fatal) {
> > > printk(KERN_DEFAULT CUT_HERE);
> > > +#ifdef CONFIG_BUG
> > > __warn(__FILE__, __LINE__, (void *)regs->ip, TAINT_WARN, regs, NULL);
> > > +#endif
> >
> > This really should be done with an #ifdef'd stub in in bug.h, not an
> > #ifdef at every call site. I assume there was a good reason for not
> > using the normal WARN*() macros.
>
> I think the idea was to have the pr_err() unconditional, and if you have
> the fancy crap on also print a full backtrace or something.
>
> But yeah, a few stubs in bug.h ought to make this go away too.

As pointed out by Boris, __warn is actually uncondtionally defined in
panic.c, the below seems to build.

---
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index edb0e2a602a8..ba1f860af38b 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -21,6 +21,12 @@
#include <linux/panic.h>
#include <linux/printk.h>

+struct warn_args;
+struct pt_regs;
+
+void __warn(const char *file, int line, void *caller, unsigned taint,
+ struct pt_regs *regs, struct warn_args *args);
+
#ifdef CONFIG_BUG

#ifdef CONFIG_GENERIC_BUG
@@ -110,11 +116,6 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
#endif

/* used internally by panic.c */
-struct warn_args;
-struct pt_regs;
-
-void __warn(const char *file, int line, void *caller, unsigned taint,
- struct pt_regs *regs, struct warn_args *args);

#ifndef WARN_ON
#define WARN_ON(condition) ({ \

2022-04-26 09:12:55

by Stephen Zhang

Subject: Re: [PATCH] x86/traps: add CONFIG_BUG to the use of __warn()

> As pointed out by Boris, __warn is actually uncondtionally defined in
> panic.c, the below seems to build.
>
> ---
> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index edb0e2a602a8..ba1f860af38b 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -21,6 +21,12 @@
> #include <linux/panic.h>
> #include <linux/printk.h>
>
> +struct warn_args;
> +struct pt_regs;
> +
> +void __warn(const char *file, int line, void *caller, unsigned taint,
> + struct pt_regs *regs, struct warn_args *args);
> +
> #ifdef CONFIG_BUG
>
> #ifdef CONFIG_GENERIC_BUG
> @@ -110,11 +116,6 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
> #endif
>
> /* used internally by panic.c */
> -struct warn_args;
> -struct pt_regs;
> -
> -void __warn(const char *file, int line, void *caller, unsigned taint,
> - struct pt_regs *regs, struct warn_args *args);
>
> #ifndef WARN_ON
> #define WARN_ON(condition) ({ \

Thanks.I will make a new version based on this suggestion.