[PATCH 1/3] powerpc: don't use __WARN() for WARN_ON()

From: Christophe Leroy
Date: Mon Aug 19 2019 - 09:06:33 EST

__WARN() used to just call __WARN_TAINT(TAINT_WARN)

But a call to printk() has been added in the commit identified below
to print a "---- cut here ----" line.

This change only applies to warnings using __WARN(), which means
WARN_ON() where the condition is constant at compile time.
For WARN_ON() with a non constant condition, the additional line is
not printed.

In addition, adding a call to printk() forces GCC to add a stack frame
and save volatile registers. Powerpc has been using traps to implement
warnings in order to avoid that.

So, call __WARN_TAINT(TAINT_WARN) directly instead of using __WARN()
in order to restore the previous behaviour.

If one day powerpc wants the decorative "---- cut here ----" line, it
has to be done in the trap handler, not in the WARN_ON() macro.

Fixes: 6b15f678fb7d ("include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures")
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
arch/powerpc/include/asm/bug.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index fed7e6241349..3928fdaebb71 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -99,7 +99,7 @@
int __ret_warn_on = !!(x); \
if (__builtin_constant_p(__ret_warn_on)) { \
if (__ret_warn_on) \
- __WARN(); \
} else { \
__asm__ __volatile__( \
"1: "PPC_TLNEI" %4,0\n" \