From 062b1c19b879e7831cbceb599ab1d758f87eda40 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Tue, 27 Jan 2015 01:15:10 +0300 Subject: [PATCH] xtensa: clean up access to spilled registers locations Define macros SPILL_SLOT* that return a reference to the stack location of the spill slot for specific register and use them instead of opencoded address calculations. Signed-off-by: Max Filippov --- arch/xtensa/include/asm/processor.h | 15 +++++++++++++ arch/xtensa/kernel/process.c | 8 +++---- arch/xtensa/kernel/signal.c | 10 ++++----- arch/xtensa/kernel/stacktrace.c | 35 +++++++---------------------- 4 files changed, 32 insertions(+), 36 deletions(-) diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h index 86ffcd68e496..003eeee3fbc6 100644 --- a/arch/xtensa/include/asm/processor.h +++ b/arch/xtensa/include/asm/processor.h @@ -113,6 +113,21 @@ */ #define MAKE_PC_FROM_RA(ra,sp) (((ra) & 0x3fffffff) | ((sp) & 0xc0000000)) +/* Spill slot location for the register reg in the spill area under the stack + * pointer sp. reg must be in the range [0..4). + */ +#define SPILL_SLOT(sp, reg) (*(((unsigned long *)(sp)) - 4 + (reg))) + +/* Spill slot location for the register reg in the spill area under the stack + * pointer sp for the call8. reg must be in the range [4..8). + */ +#define SPILL_SLOT_CALL8(sp, reg) (*(((unsigned long *)(sp)) - 12 + (reg))) + +/* Spill slot location for the register reg in the spill area under the stack + * pointer sp for the call12. reg must be in the range [4..12). + */ +#define SPILL_SLOT_CALL12(sp, reg) (*(((unsigned long *)(sp)) - 16 + (reg))) + typedef struct { unsigned long seg; } mm_segment_t; diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 58f96d1230d4..ff4f0ecb03dd 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -204,8 +204,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn, #endif /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */ - *((int*)childregs - 3) = (unsigned long)childregs; - *((int*)childregs - 4) = 0; + SPILL_SLOT(childregs, 1) = (unsigned long)childregs; + SPILL_SLOT(childregs, 0) = 0; p->thread.sp = (unsigned long)childregs; @@ -266,8 +266,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn, /* pass parameters to ret_from_kernel_thread: * a2 = thread_fn, a3 = thread_fn arg */ - *((int *)childregs - 1) = thread_fn_arg; - *((int *)childregs - 2) = usp_thread_fn; + SPILL_SLOT(childregs, 3) = thread_fn_arg; + SPILL_SLOT(childregs, 2) = usp_thread_fn; /* Childregs are only used when we're going to userspace * in which case start_thread will set them up. diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c index 70a131945443..d427e784ab44 100644 --- a/arch/xtensa/kernel/signal.c +++ b/arch/xtensa/kernel/signal.c @@ -91,14 +91,14 @@ flush_window_regs_user(struct pt_regs *regs) inc = 1; } else if (m & 4) { /* call8 */ - if (copy_to_user((void*)(sp - 32), - ®s->areg[(base + 1) * 4], 16)) + if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4), + ®s->areg[(base + 1) * 4], 16)) goto errout; inc = 2; } else if (m & 8) { /* call12 */ - if (copy_to_user((void*)(sp - 48), - ®s->areg[(base + 1) * 4], 32)) + if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4), + ®s->areg[(base + 1) * 4], 32)) goto errout; inc = 3; } @@ -106,7 +106,7 @@ flush_window_regs_user(struct pt_regs *regs) /* Save current frame a0..a3 under next SP */ sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; - if (copy_to_user((void*)(sp - 16), ®s->areg[base * 4], 16)) + if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16)) goto errout; /* Get current stack pointer for next loop iteration. */ diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c index e7d30ee0fd48..0df4080fa20f 100644 --- a/arch/xtensa/kernel/stacktrace.c +++ b/arch/xtensa/kernel/stacktrace.c @@ -23,14 +23,6 @@ */ extern int common_exception_return; -/* A struct that maps to the part of the frame containing the a0 and - * a1 registers. - */ -struct frame_start { - unsigned long a0; - unsigned long a1; -}; - void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth, int (*ufn)(struct stackframe *frame, void *data), void *data) @@ -96,26 +88,16 @@ void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth, /* Start from the a1 register. */ /* a1 = regs->areg[1]; */ while (a0 != 0 && depth--) { - struct frame_start frame_start; - /* Get the location for a1, a0 for the - * previous frame from the current a1. - */ - unsigned long *psp = (unsigned long *)a1; - - psp -= 4; + pc = MAKE_PC_FROM_RA(a0, pc); /* Check if the region is OK to access. */ - if (!access_ok(VERIFY_READ, psp, sizeof(frame_start))) + if (!access_ok(VERIFY_READ, &SPILL_SLOT(a1, 0), 8)) return; /* Copy a1, a0 from user space stack frame. */ - if (__copy_from_user_inatomic(&frame_start, psp, - sizeof(frame_start))) + if (__get_user(a0, &SPILL_SLOT(a1, 0)) || + __get_user(a1, &SPILL_SLOT(a1, 1))) return; - pc = MAKE_PC_FROM_RA(a0, pc); - a0 = frame_start.a0; - a1 = frame_start.a1; - frame.pc = pc; frame.sp = a1; @@ -147,7 +129,6 @@ void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth, */ while (a1 > sp_start && a1 < sp_end && depth--) { struct stackframe frame; - unsigned long *psp = (unsigned long *)a1; frame.pc = pc; frame.sp = a1; @@ -171,8 +152,8 @@ void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth, sp_start = a1; pc = MAKE_PC_FROM_RA(a0, pc); - a0 = *(psp - 4); - a1 = *(psp - 3); + a0 = SPILL_SLOT(a1, 0); + a1 = SPILL_SLOT(a1, 1); } } EXPORT_SYMBOL(xtensa_backtrace_kernel); @@ -196,8 +177,8 @@ void walk_stackframe(unsigned long *sp, sp = (unsigned long *)a1; - a0 = *(sp - 4); - a1 = *(sp - 3); + a0 = SPILL_SLOT(a1, 0); + a1 = SPILL_SLOT(a1, 1); if (a1 <= (unsigned long)sp) break; -- 2.20.1