LoongArch: Remove unused kernel stack padding

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>

diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
index 6954dc5..7184f1d 100644 (file)
--- a/arch/loongarch/include/asm/processor.h
+++ b/arch/loongarch/include/asm/processor.h
@@ -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])

diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/asm/ptrace.h
index 17838c6..82649a7 100644 (file)
--- a/arch/loongarch/include/asm/ptrace.h
+++ b/arch/loongarch/include/asm/ptrace.h
@@ -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 */

diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index 9742577..84970e2 100644 (file)
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -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()

diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index 1256e35..2526b68 100644 (file)
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -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;

diff --git a/arch/loongarch/kernel/switch.S b/arch/loongarch/kernel/switch.S
index 43ebbc3..202a163 100644 (file)
--- a/arch/loongarch/kernel/switch.S
+++ b/arch/loongarch/kernel/switch.S
@@ -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