From 16f9afe651e8197fb7ce6df0990d8e2ad779e1af Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Mon, 27 May 2013 21:43:41 +0530 Subject: [PATCH] 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/include/asm/entry.h | 14 +++----------- arch/arc/include/asm/processor.h | 11 ++++++++--- arch/arc/include/asm/ptrace.h | 1 - arch/arc/include/uapi/asm/ptrace.h | 2 +- arch/arc/kernel/asm-offsets.c | 1 + arch/arc/kernel/ctx_sw.c | 14 +++++--------- arch/arc/kernel/process.c | 4 +--- arch/arc/kernel/ptrace.c | 6 ++++-- arch/arc/kernel/stacktrace.c | 2 +- 9 files changed, 24 insertions(+), 31 deletions(-) diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h index 5ff7b8dd3d5b..820202af21a5 100644 --- a/arch/arc/include/asm/entry.h +++ b/arch/arc/include/asm/entry.h @@ -124,8 +124,6 @@ st.a r25, [sp, -4] #endif - /* move up by 1 word to "create" callee_regs->"stack_place_holder" */ - sub sp, sp, 4 .endm /*-------------------------------------------------------------- @@ -148,10 +146,9 @@ st.a r23, [sp, -4] st.a r24, [sp, -4] #ifdef CONFIG_ARC_CURR_IN_REG - sub sp, sp, 8 + sub sp, sp, 4 #else st.a r25, [sp, -4] - sub sp, sp, 4 #endif .endm @@ -168,14 +165,11 @@ *-------------------------------------------------------------*/ .macro RESTORE_CALLEE_SAVED_KERNEL - #ifdef CONFIG_ARC_CURR_IN_REG - add sp, sp, 8 /* skip callee_reg gutter and user r25 placeholder */ + add sp, sp, 4 /* skip usual r25 placeholder */ #else - add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */ ld.ab r25, [sp, 4] #endif - ld.ab r24, [sp, 4] ld.ab r23, [sp, 4] ld.ab r22, [sp, 4] @@ -203,8 +197,6 @@ *-------------------------------------------------------------*/ .macro RESTORE_CALLEE_SAVED_USER - add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */ - #ifdef CONFIG_ARC_CURR_IN_REG ld.ab r12, [sp, 4] st r12, [r25, TASK_THREAD + THREAD_USER_R25] @@ -230,7 +222,7 @@ * Super FAST Restore callee saved regs by simply re-adjusting SP *-------------------------------------------------------------*/ .macro DISCARD_CALLEE_SAVED_USER - add sp, sp, 14 * 4 + add sp, sp, SZ_CALLEE_REGS .endm /*-------------------------------------------------------------- diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h index 81efbcae3839..8c77e623c4e5 100644 --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.h @@ -19,6 +19,7 @@ #ifndef __ASSEMBLY__ #include /* for STATUS_E1_MASK et all */ +#include /* Arch specific stuff which needs to be saved per task. * However these items are not so important so as to earn a place in @@ -75,11 +76,15 @@ unsigned long thread_saved_pc(struct task_struct *t); /* * Where abouts of Task's sp, fp, blink when it was last seen in kernel mode. - * These can't be derived from pt_regs as that would give correp user-mode val + * Look in process.c for details of kernel stack layout */ #define KSTK_ESP(tsk) (tsk->thread.ksp) -#define KSTK_BLINK(tsk) (*((unsigned int *)((KSTK_ESP(tsk)) + (13+1+1)*4))) -#define KSTK_FP(tsk) (*((unsigned int *)((KSTK_ESP(tsk)) + (13+1)*4))) + +#define KSTK_REG(tsk, off) (*((unsigned int *)(KSTK_ESP(tsk) + \ + sizeof(struct callee_regs) + off))) + +#define KSTK_BLINK(tsk) KSTK_REG(tsk, 4) +#define KSTK_FP(tsk) KSTK_REG(tsk, 0) /* * Do necessary setup to start up a newly executed thread. diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h index 7491bb7428bd..47801ba135b3 100644 --- a/arch/arc/include/asm/ptrace.h +++ b/arch/arc/include/asm/ptrace.h @@ -59,7 +59,6 @@ struct pt_regs { /* Callee saved registers - need to be saved only when you are scheduled out */ struct callee_regs { - long res; /* Again this is not needed */ long r25; long r24; long r23; diff --git a/arch/arc/include/uapi/asm/ptrace.h b/arch/arc/include/uapi/asm/ptrace.h index e0e8403f181f..4599109f68f2 100644 --- a/arch/arc/include/uapi/asm/ptrace.h +++ b/arch/arc/include/uapi/asm/ptrace.h @@ -38,8 +38,8 @@ struct user_regs_struct { long r12, r11, r10, r9, r8, r7, r6, r5, r4, r3, r2, r1, r0; long sp; } scratch; + long pad2; struct { - long pad; long r25, r24, r23, r22, r21, r20; long r19, r18, r17, r16, r15, r14, r13; } callee; diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c index 7dcda7025241..fdcd76532b70 100644 --- a/arch/arc/kernel/asm-offsets.c +++ b/arch/arc/kernel/asm-offsets.c @@ -60,5 +60,6 @@ int main(void) DEFINE(PT_r6, offsetof(struct pt_regs, r6)); DEFINE(PT_r7, offsetof(struct pt_regs, r7)); + DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs)); return 0; } 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" ); diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c index 949bfd5d62a0..db868db82944 100644 --- a/arch/arc/kernel/process.c +++ b/arch/arc/kernel/process.c @@ -55,10 +55,8 @@ asmlinkage void ret_from_fork(void); * | ... | * | unused | * | | - * ------------------ <==== top of Stack (thread.ksp) - * | UNUSED 1 word| * ------------------ - * | r25 | + * | r25 | <==== top of Stack (thread.ksp) * ~ ~ * | --to-- | (CALLEE Regs of user mode) * | r13 | diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c index 6e467e3585b0..333238564b67 100644 --- a/arch/arc/kernel/ptrace.c +++ b/arch/arc/kernel/ptrace.c @@ -48,6 +48,7 @@ static int genregs_get(struct task_struct *target, REG_O_ZERO(pad); REG_O_CHUNK(scratch, callee, ptregs); + REG_O_ZERO(pad2); REG_O_CHUNK(callee, efa, cregs); REG_O_CHUNK(efa, stop_pc, &target->thread.fault_address); @@ -96,8 +97,9 @@ static int genregs_set(struct task_struct *target, offsetof(struct user_regs_struct, LOC) + 4); REG_IGNORE_ONE(pad); - /* TBD: disallow updates to STATUS32, orig_r8 etc*/ - REG_IN_CHUNK(scratch, callee, ptregs); /* pt_regs[bta..orig_r8] */ + /* TBD: disallow updates to STATUS32 etc*/ + REG_IN_CHUNK(scratch, pad2, ptregs); /* pt_regs[bta..sp] */ + REG_IGNORE_ONE(pad2); REG_IN_CHUNK(callee, efa, cregs); /* callee_regs[r25..r13] */ REG_IGNORE_ONE(efa); /* efa update invalid */ REG_IN_ONE(stop_pc, &ptregs->ret); /* stop_pc: PC update */ diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c index ca0207b9d5b6..f8b7d880304d 100644 --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -79,7 +79,7 @@ static void seed_unwind_frame_info(struct task_struct *tsk, * assembly code */ frame_info->regs.r27 = 0; - frame_info->regs.r28 += 64; + frame_info->regs.r28 += 60; frame_info->call_frame = 0; } else {