Re: [PATCH] powerpc: Don't allow the use of EMIT_BUG_ENTRY with BUGFLAG_WARNING

[Michael Ellerman]

On Sun, 13 Feb 2022 10:02:41 +0100, Christophe Leroy wrote:
> Warnings in assembly must use EMIT_WARN_ENTRY in order to generate
> the necessary entry in exception table.
> 
> Check in EMIT_BUG_ENTRY that flags don't include BUGFLAG_WARNING.
> 
> This change avoids problems like the one fixed by
> commit fd1ea686 ("powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug
> warnings").
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc: Don't allow the use of EMIT_BUG_ENTRY with BUGFLAG_WARNING
  https://git.kernel.org/powerpc/c/38a1756861b8fc2ea9afb93e231194c642a4e261

cheers

[PATCH] powerpc: Don't allow the use of EMIT_BUG_ENTRY with BUGFLAG_WARNING

[Christophe Leroy]

Warnings in assembly must use EMIT_WARN_ENTRY in order to generate
the necessary entry in exception table.

Check in EMIT_BUG_ENTRY that flags don't include BUGFLAG_WARNING.

This change avoids problems like the one fixed by
commit fd1ea686 ("powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug
warnings").

Signed-off-by: Christophe Leroy 
---
 arch/powerpc/include/asm/bug.h | 13 ++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 02c08d1492f8..ecbae1832de3 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -11,7 +11,7 @@
 #ifdef __ASSEMBLY__
 #include 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
-.macro EMIT_BUG_ENTRY addr,file,line,flags
+.macro __EMIT_BUG_ENTRY addr,file,line,flags
 .section __bug_table,"aw"
 5001:   .4byte \addr - 5001b, 5002f - 5001b
 .short \line, \flags
@@ -22,7 +22,7 @@
 .previous
 .endm
 #else
-.macro EMIT_BUG_ENTRY addr,file,line,flags
+.macro __EMIT_BUG_ENTRY addr,file,line,flags
 .section __bug_table,"aw"
 5001:   .4byte \addr - 5001b
 .short \flags
@@ -33,7 +33,14 @@
 
 .macro EMIT_WARN_ENTRY addr,file,line,flags
EX_TABLE(\addr,\addr+4)
-   EMIT_BUG_ENTRY \addr,\file,\line,\flags
+   __EMIT_BUG_ENTRY \addr,\file,\line,\flags
+.endm
+
+.macro EMIT_BUG_ENTRY addr,file,line,flags
+   .if \flags & 1 /* BUGFLAG_WARNING */
+   .err /* Use EMIT_WARN_ENTRY for warnings */
+   .endif
+   __EMIT_BUG_ENTRY \addr,\file,\line,\flags
 .endm
 
 #else /* !__ASSEMBLY__ */
-- 
2.34.1