diff options
Diffstat (limited to 'arch/xtensa/oprofile/backtrace.c')
| -rw-r--r-- | arch/xtensa/oprofile/backtrace.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/arch/xtensa/oprofile/backtrace.c b/arch/xtensa/oprofile/backtrace.c new file mode 100644 index 000000000..5f03a593d --- /dev/null +++ b/arch/xtensa/oprofile/backtrace.c @@ -0,0 +1,169 @@ +/** + * @file backtrace.c + * + * @remark Copyright 2008 Tensilica Inc. + * @remark Read the file COPYING + * + */ + +#include <linux/oprofile.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <asm/ptrace.h> +#include <asm/uaccess.h> +#include <asm/traps.h> + +/* 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; +}; + +static void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth) +{ + 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 = MAKE_PC_FROM_RA(a0, regs->pc); + int index; + + /* First add the current PC to the trace. */ + if (pc != 0 && pc <= TASK_SIZE) + oprofile_add_trace(pc); + else + 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)) { + /* Read a0 and a1 from the + * corresponding position in AREGs. + */ + a0 = regs->areg[index * 4]; + a1 = regs->areg[index * 4 + 1]; + /* Get the PC from a0 and a1. */ + pc = MAKE_PC_FROM_RA(a0, pc); + + /* Add the PC to the trace. */ + if (pc != 0 && pc <= TASK_SIZE) + oprofile_add_trace(pc); + else + return; + } + + /* Step 2. */ + /* We are done with the register window, we need to + * look through the stack. + */ + if (depth > 0) { + /* 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; + + a0 = frame_start.a0; + a1 = frame_start.a1; + pc = MAKE_PC_FROM_RA(a0, pc); + + if (pc != 0 && pc <= TASK_SIZE) + oprofile_add_trace(pc); + else + return; + } + } +} + +static void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth) +{ + unsigned long pc = regs->pc; + unsigned long *psp; + 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--) { + pc = MAKE_PC_FROM_RA(a0, pc); + + /* Add the PC to the trace. */ + oprofile_add_trace(pc); + if (pc == (unsigned long) &common_exception_return) { + regs = (struct pt_regs *)a1; + if (user_mode(regs)) { + pc = regs->pc; + if (pc != 0 && pc <= TASK_SIZE) + oprofile_add_trace(pc); + else + return; + return xtensa_backtrace_user(regs, depth); + } + a0 = regs->areg[0]; + a1 = regs->areg[1]; + continue; + } + + psp = (unsigned long *)a1; + + a0 = *(psp - 4); + a1 = *(psp - 3); + + if (a1 <= (unsigned long)psp) + return; + + } + return; +} + +void xtensa_backtrace(struct pt_regs * const regs, unsigned int depth) +{ + if (user_mode(regs)) + xtensa_backtrace_user(regs, depth); + else + xtensa_backtrace_kernel(regs, depth); +} |