linux-kernel - [PATCH v1 1/1] x86/fred: Fix init_task thread stack pointer initialization

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Date: Fri,  1 Mar 2024 00:40:46 -0800
From: "Xin Li (Intel)" <xin@...or.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        brgerst@...il.com
Subject: [PATCH v1 1/1] x86/fred: Fix init_task thread stack pointer initialization

As TOP_OF_KERNEL_STACK_PADDING is defined as 0 on x86_64, no one noticed
it's missing in the calculation of the .sp field in INIT_THREAD until it
is defined to 16 with CONFIG_X86_FRED=y.

Subtract TOP_OF_KERNEL_STACK_PADDING from the .sp field of INIT_THREAD.

Fixes: 65c9cc9e2c14 ("x86/fred: Reserve space for the FRED stack frame")
Fixes: 3adee777ad0d ("x86/smpboot: Remove initial_stack on 64-bit")
Reported-by: kernel test robot <oliver.sang@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202402262159.183c2a37-lkp@intel.com
Signed-off-by: Xin Li (Intel) <xin@...or.com>
---
 arch/x86/include/asm/processor.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 26620d7642a9..17fe81998ce4 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -664,8 +664,10 @@ static __always_inline void prefetchw(const void *x)
 #else
 extern unsigned long __end_init_task[];
 
-#define INIT_THREAD {							    \
-	.sp	= (unsigned long)&__end_init_task - sizeof(struct pt_regs), \
+#define INIT_THREAD {							\
+	.sp	= (unsigned long)&__end_init_task -			\
+		  TOP_OF_KERNEL_STACK_PADDING -				\
+		  sizeof(struct pt_regs),				\
 }
 
 extern unsigned long KSTK_ESP(struct task_struct *task);

base-commit: e13841907b8fda0ae0ce1ec03684665f578416a8
-- 
2.44.0