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Diffstat (limited to 'arch/xtensa/kernel/stacktrace.c')
-rw-r--r-- | arch/xtensa/kernel/stacktrace.c | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c new file mode 100644 index 000000000..a94da7dd3 --- /dev/null +++ b/arch/xtensa/kernel/stacktrace.c @@ -0,0 +1,270 @@ +/* + * 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> +#include <linux/stacktrace.h> + +#include <asm/stacktrace.h> +#include <asm/traps.h> +#include <linux/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; + +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--) { + pc = MAKE_PC_FROM_RA(a0, pc); + + /* Check if the region is OK to access. */ + if (!access_ok(VERIFY_READ, &SPILL_SLOT(a1, 0), 8)) + return; + /* Copy a1, a0 from user space stack frame. */ + if (__get_user(a0, &SPILL_SLOT(a1, 0)) || + __get_user(a1, &SPILL_SLOT(a1, 1))) + return; + + 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; + + 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 = SPILL_SLOT(a1, 0); + a1 = SPILL_SLOT(a1, 1); + } +} +EXPORT_SYMBOL(xtensa_backtrace_kernel); + +#endif + +void walk_stackframe(unsigned long *sp, + int (*fn)(struct stackframe *frame, void *data), + void *data) +{ + unsigned long a0, a1; + unsigned long sp_end; + + a1 = (unsigned long)sp; + sp_end = ALIGN(a1, THREAD_SIZE); + + spill_registers(); + + while (a1 < sp_end) { + struct stackframe frame; + + sp = (unsigned long *)a1; + + a0 = SPILL_SLOT(a1, 0); + a1 = SPILL_SLOT(a1, 1); + + if (a1 <= (unsigned long)sp) + break; + + frame.pc = MAKE_PC_FROM_RA(a0, a1); + frame.sp = a1; + + if (fn(&frame, data)) + return; + } +} + +#ifdef CONFIG_STACKTRACE + +struct stack_trace_data { + struct stack_trace *trace; + unsigned skip; +}; + +static int stack_trace_cb(struct stackframe *frame, void *data) +{ + struct stack_trace_data *trace_data = data; + struct stack_trace *trace = trace_data->trace; + + if (trace_data->skip) { + --trace_data->skip; + return 0; + } + if (!kernel_text_address(frame->pc)) + return 0; + + trace->entries[trace->nr_entries++] = frame->pc; + return trace->nr_entries >= trace->max_entries; +} + +void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace) +{ + struct stack_trace_data trace_data = { + .trace = trace, + .skip = trace->skip, + }; + walk_stackframe(stack_pointer(task), stack_trace_cb, &trace_data); +} +EXPORT_SYMBOL_GPL(save_stack_trace_tsk); + +void save_stack_trace(struct stack_trace *trace) +{ + save_stack_trace_tsk(current, trace); +} +EXPORT_SYMBOL_GPL(save_stack_trace); + +#endif + +#ifdef CONFIG_FRAME_POINTER + +struct return_addr_data { + unsigned long addr; + unsigned skip; +}; + +static int return_address_cb(struct stackframe *frame, void *data) +{ + struct return_addr_data *r = data; + + if (r->skip) { + --r->skip; + return 0; + } + if (!kernel_text_address(frame->pc)) + return 0; + r->addr = frame->pc; + return 1; +} + +/* + * level == 0 is for the return address from the caller of this function, + * not from this function itself. + */ +unsigned long return_address(unsigned level) +{ + struct return_addr_data r = { + .skip = level, + }; + walk_stackframe(stack_pointer(NULL), return_address_cb, &r); + return r.addr; +} +EXPORT_SYMBOL(return_address); + +#endif |