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

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 0c2b1eb59943 ("powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug
warnings").

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ddcb422102a37eb45f57694c7ef0ec6187964dff.1644742951.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 02c08d1492f87bab59ee8a63c4dafc8fea5f4c3c..ecbae1832de31ffd540ccaaf085d288d478c83ab 100644 (file)
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -11,7 +11,7 @@
 #ifdef __ASSEMBLY__
 #include <asm/asm-offsets.h>
 #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__ */