diff options
Diffstat (limited to 'arch/xtensa/kernel/stacktrace.c')
| -rw-r--r-- | arch/xtensa/kernel/stacktrace.c | 167 |
1 files changed, 166 insertions, 1 deletions
diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c index 7d2c317bd98b..7538d802b65a 100644 --- a/arch/xtensa/kernel/stacktrace.c +++ b/arch/xtensa/kernel/stacktrace.c @@ -1,11 +1,12 @@ /* - * arch/xtensa/kernel/stacktrace.c + * Kernel and userspace stack tracing. * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2001 - 2013 Tensilica Inc. + * Copyright (C) 2015 Cadence Design Systems Inc. */ #include <linux/export.h> #include <linux/sched.h> @@ -13,6 +14,170 @@ #include <asm/stacktrace.h> #include <asm/traps.h> +#include <asm/uaccess.h> + +#if IS_ENABLED(CONFIG_OPROFILE) || IS_ENABLED(CONFIG_PERF_EVENTS) + +/* Address of common_exception_return, used to check the + * transition from kernel to user space. + */ +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) +{ + unsigned long windowstart = regs->windowstart; + unsigned long windowbase = regs->windowbase; + unsigned long a0 = regs->areg[0]; + unsigned long a1 = regs->areg[1]; + unsigned long pc = regs->pc; + struct stackframe frame; + int index; + + if (!depth--) + return; + + frame.pc = pc; + frame.sp = a1; + + if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data)) + return; + + /* Two steps: + * + * 1. Look through the register window for the + * previous PCs in the call trace. + * + * 2. Look on the stack. + */ + + /* Step 1. */ + /* Rotate WINDOWSTART to move the bit corresponding to + * the current window to the bit #0. + */ + windowstart = (windowstart << WSBITS | windowstart) >> windowbase; + + /* Look for bits that are set, they correspond to + * valid windows. + */ + for (index = WSBITS - 1; (index > 0) && depth; depth--, index--) + if (windowstart & (1 << index)) { + /* Get the PC from a0 and a1. */ + pc = MAKE_PC_FROM_RA(a0, pc); + /* Read a0 and a1 from the + * corresponding position in AREGs. + */ + a0 = regs->areg[index * 4]; + a1 = regs->areg[index * 4 + 1]; + + frame.pc = pc; + frame.sp = a1; + + if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data)) + return; + } + + /* Step 2. */ + /* We are done with the register window, we need to + * look through the stack. + */ + if (!depth) + return; + + /* 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; + + /* Check if the region is OK to access. */ + if (!access_ok(VERIFY_READ, psp, sizeof(frame_start))) + return; + /* Copy a1, a0 from user space stack frame. */ + if (__copy_from_user_inatomic(&frame_start, psp, + sizeof(frame_start))) + return; + + pc = MAKE_PC_FROM_RA(a0, pc); + a0 = frame_start.a0; + a1 = frame_start.a1; + + frame.pc = pc; + frame.sp = a1; + + if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data)) + return; + } +} +EXPORT_SYMBOL(xtensa_backtrace_user); + +void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth, + int (*kfn)(struct stackframe *frame, void *data), + int (*ufn)(struct stackframe *frame, void *data), + void *data) +{ + unsigned long pc = regs->depc > VALID_DOUBLE_EXCEPTION_ADDRESS ? + regs->depc : regs->pc; + unsigned long sp_start, sp_end; + unsigned long a0 = regs->areg[0]; + unsigned long a1 = regs->areg[1]; + + sp_start = a1 & ~(THREAD_SIZE - 1); + sp_end = sp_start + THREAD_SIZE; + + /* Spill the register window to the stack first. */ + spill_registers(); + + /* Read the stack frames one by one and create the PC + * from the a0 and a1 registers saved there. + */ + while (a1 > sp_start && a1 < sp_end && depth--) { + struct stackframe frame; + unsigned long *psp = (unsigned long *)a1; + + frame.pc = pc; + frame.sp = a1; + + if (kernel_text_address(pc) && kfn(&frame, data)) + return; + + if (pc == (unsigned long)&common_exception_return) { + regs = (struct pt_regs *)a1; + if (user_mode(regs)) { + if (ufn == NULL) + return; + xtensa_backtrace_user(regs, depth, ufn, data); + return; + } + a0 = regs->areg[0]; + a1 = regs->areg[1]; + continue; + } + + sp_start = a1; + + pc = MAKE_PC_FROM_RA(a0, pc); + a0 = *(psp - 4); + a1 = *(psp - 3); + } +} +EXPORT_SYMBOL(xtensa_backtrace_kernel); + +#endif void walk_stackframe(unsigned long *sp, int (*fn)(struct stackframe *frame, void *data), |