From 16f9afe651e8197fb7ce6df0990d8e2ad779e1af Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Mon, 27 May 2013 21:43:41 +0530 Subject: ARC: pt_regs update #3: Remove unused gutter at start of callee_regs This is trickier than prev two: * context switching code saves kernel mode callee regs in the format of struct callee_regs thus needs adjustment. This also reduces the height of topmost kernel stack frame by 1 word. * Since kernel stack unwinder is sensitive to height of topmost kernel stack frame, that needs a word of adjustment too. ptrace needs a bit of updating since pt_regs now diverges from user_regs_struct. Signed-off-by: Vineet Gupta --- arch/arc/kernel/ctx_sw.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'arch/arc/kernel/ctx_sw.c') diff --git a/arch/arc/kernel/ctx_sw.c b/arch/arc/kernel/ctx_sw.c index 60844dac6132..34410eb1a308 100644 --- a/arch/arc/kernel/ctx_sw.c +++ b/arch/arc/kernel/ctx_sw.c @@ -23,10 +23,6 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task) unsigned int tmp; unsigned int prev = (unsigned int)prev_task; unsigned int next = (unsigned int)next_task; - int num_words_to_skip = 1; -#ifdef CONFIG_ARC_CURR_IN_REG - num_words_to_skip++; -#endif __asm__ __volatile__( /* FP/BLINK save generated by gcc (standard function prologue */ @@ -44,8 +40,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task) "st.a r24, [sp, -4] \n\t" #ifndef CONFIG_ARC_CURR_IN_REG "st.a r25, [sp, -4] \n\t" +#else + "sub sp, sp, 4 \n\t" /* usual r25 placeholder */ #endif - "sub sp, sp, %4 \n\t" /* create gutter at top */ /* set ksp of outgoing task in tsk->thread.ksp */ "st.as sp, [%3, %1] \n\t" @@ -76,10 +73,10 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task) /* start loading it's CALLEE reg file */ - "add sp, sp, %4 \n\t" /* skip gutter at top */ - #ifndef CONFIG_ARC_CURR_IN_REG "ld.ab r25, [sp, 4] \n\t" +#else + "add sp, sp, 4 \n\t" #endif "ld.ab r24, [sp, 4] \n\t" "ld.ab r23, [sp, 4] \n\t" @@ -100,8 +97,7 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task) /* FP/BLINK restore generated by gcc (standard func epilogue */ : "=r"(tmp) - : "n"((TASK_THREAD + THREAD_KSP) / 4), "r"(next), "r"(prev), - "n"(num_words_to_skip * 4) + : "n"((TASK_THREAD + THREAD_KSP) / 4), "r"(next), "r"(prev) : "blink" ); -- cgit v1.2.3