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From b99a048c6c7d9dcf2d34f8069c4bde6943dfc860 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 26 Mar 2019 18:31:29 +0100
Subject: [PATCH 40/43] powerpc/stackprotector: work around stack-guard init
from atomic
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.12/older/patches-6.12.66-rt15.tar.xz
This is invoked from the secondary CPU in atomic context. On x86 we use
tsc instead. On Power we XOR it against mftb() so lets use stack address
as the initial value.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/powerpc/include/asm/stackprotector.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/stackprotector.h b/arch/powerpc/include/asm/stackprotector.h
index 283c34647856..4727f40052dd 100644
--- a/arch/powerpc/include/asm/stackprotector.h
+++ b/arch/powerpc/include/asm/stackprotector.h
@@ -19,8 +19,13 @@
*/
static __always_inline void boot_init_stack_canary(void)
{
- unsigned long canary = get_random_canary();
+ unsigned long canary;
+#ifndef CONFIG_PREEMPT_RT
+ canary = get_random_canary();
+#else
+ canary = ((unsigned long)&canary) & CANARY_MASK;
+#endif
current->stack_canary = canary;
#ifdef CONFIG_PPC64
get_paca()->canary = canary;
--
2.52.0
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