linux-kernel - [PATCH 10/20] ARC: kernel stack: INIT_THREAD need not setup @init

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Message-Id: <20230815004813.555115-11-vgupta@kernel.org>
Date:   Mon, 14 Aug 2023 17:48:03 -0700
From:   Vineet Gupta <vgupta@...nel.org>
To:     linux-snps-arc@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org,
        Shahab Vahedi <Shahab.Vahedi@...opsys.com>,
        Alexey Brodkin <abrodkin@...opsys.com>,
        Vineet Gupta <vgupta@...nel.org>
Subject: [PATCH 10/20] ARC: kernel stack: INIT_THREAD need not setup @init_stack in @ksp

There are 2 pointers to kernel mode stack of a task
 - task_struct.stack: base address of stack page (max possible stack top)
 - thread_info.ksp  : runtime stack top in __switch_to

INIT_THREAD was setting up ksp to stack base which was not really needed
 - it would get overwritten with dynamic value on first call to
   __switch_to when init is switched out for the very first time.
 - generic code already does
      init_task.stack = init_stack
   and ARC code uses that to retrieve task's stack base.

Signed-off-by: Vineet Gupta <vgupta@...nel.org>
---
 arch/arc/include/asm/processor.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index fb844fce1ab6..82ddc929d6e7 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -33,9 +33,7 @@ struct thread_struct {
 #endif
 };
 
-#define INIT_THREAD  {                          \
-	.ksp = sizeof(init_stack) + (unsigned long) init_stack, \
-}
+#define INIT_THREAD  { }
 
 /* Forward declaration, a strange C thing */
 struct task_struct;
-- 
2.34.1