linux-kernel - [PATCH] powerpc/interrupt: Do not call single_step

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Date:   Tue, 10 Aug 2021 16:13:17 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com,
        userm57@...oo.com, fthain@...ux-m68k.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/interrupt: Do not call single_step_exception() from
 other exceptions

single_step_exception() is called by emulate_single_step() which
is called from (at least) alignment exception() handler and
program_check_exception() handler.

Redefine it as a regular __single_step_exception() which is called
by both single_step_exception() handler and emulate_single_step()
function.

Fixes: 3a96570ffceb ("powerpc: convert interrupt handlers to use wrappers")
Cc: stable@...r.kernel.org
Cc: Stan Johnson <userm57@...oo.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Finn Thain <fthain@...ux-m68k.org>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/traps.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index dfbce527c98e..d56254f05e17 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1104,7 +1104,7 @@ DEFINE_INTERRUPT_HANDLER(RunModeException)
 	_exception(SIGTRAP, regs, TRAP_UNK, 0);
 }
 
-DEFINE_INTERRUPT_HANDLER(single_step_exception)
+static void __single_step_exception(struct pt_regs *regs)
 {
 	clear_single_step(regs);
 	clear_br_trace(regs);
@@ -1121,6 +1121,11 @@ DEFINE_INTERRUPT_HANDLER(single_step_exception)
 	_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
 }
 
+DEFINE_INTERRUPT_HANDLER(single_step_exception)
+{
+	__single_step_exception(regs);
+}
+
 /*
  * After we have successfully emulated an instruction, we have to
  * check if the instruction was being single-stepped, and if so,
@@ -1130,7 +1135,7 @@ DEFINE_INTERRUPT_HANDLER(single_step_exception)
 static void emulate_single_step(struct pt_regs *regs)
 {
 	if (single_stepping(regs))
-		single_step_exception(regs);
+		__single_step_exception(regs);
 }
 
 static inline int __parse_fpscr(unsigned long fpscr)
-- 
2.25.0