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LoongArch: Remove unused kernel stack padding

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The current LoongArch kernel stack is padded as if obeying the MIPS o32
calling convention (32 bytes), signifying the port's MIPS lineage but no
longer making sense. Remove the padding for clarity.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Jinyang He 2022-10-29 16:29:31 +08:00 committed by Huacai Chen
parent 247f34f7b8
commit b40fa75e15
5 changed files with 6 additions and 7 deletions
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2
arch/loongarch/include/asm/processor.h
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@ -191,7 +191,7 @@ static inline void flush_thread(void)
unsigned long __get_wchan(struct task_struct *p);
#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
THREAD_SIZE - 32 - sizeof(struct pt_regs))
THREAD_SIZE - sizeof(struct pt_regs))
#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk))
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->csr_era)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[3])

2
arch/loongarch/include/asm/ptrace.h
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@ -133,7 +133,7 @@ static inline void die_if_kernel(const char *str, struct pt_regs *regs)
#define current_pt_regs() \
({ \
unsigned long sp = (unsigned long)__builtin_frame_address(0); \
(struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1 - 32) - 1; \
(struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1) - 1; \
})
/* Helpers for working with the user stack pointer */

3
arch/loongarch/kernel/head.S
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@ -84,10 +84,9 @@ SYM_CODE_START(kernel_entry) # kernel entry point
la.pcrel tp, init_thread_union
/* Set the SP after an empty pt_regs. */
PTR_LI sp, (_THREAD_SIZE - 32 - PT_SIZE)
PTR_LI sp, (_THREAD_SIZE - PT_SIZE)
PTR_ADD sp, sp, tp
set_saved_sp sp, t0, t1
PTR_ADDI sp, sp, -4 * SZREG # init stack pointer
bl start_kernel
ASM_BUG()

4
arch/loongarch/kernel/process.c
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@ -129,7 +129,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
unsigned long clone_flags = args->flags;
struct pt_regs *childregs, *regs = current_pt_regs();
childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
/* set up new TSS. */
childregs = (struct pt_regs *) childksp - 1;
@ -236,7 +236,7 @@ bool in_task_stack(unsigned long stack, struct task_struct *task,
struct stack_info *info)
{
unsigned long begin = (unsigned long)task_stack_page(task);
unsigned long end = begin + THREAD_SIZE - 32;
unsigned long end = begin + THREAD_SIZE;
if (stack < begin || stack >= end)
return false;

2
arch/loongarch/kernel/switch.S
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@ -26,7 +26,7 @@ SYM_FUNC_START(__switch_to)
move tp, a2
cpu_restore_nonscratch a1
li.w t0, _THREAD_SIZE - 32
li.w t0, _THREAD_SIZE
PTR_ADD t0, t0, tp
set_saved_sp t0, t1, t2