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Subject[PATCH v2 03/13] xtensa: move oprofile stack tracing to stacktrace.c
Date
Old oprofile interface will share user stack tracing with new perf
interface. Move oprofile user/kernel stack tracing to stacktrace.c to
make it possible.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
arch/xtensa/include/asm/stacktrace.h | 8 ++
arch/xtensa/kernel/stacktrace.c | 167 ++++++++++++++++++++++++++++++++++-
arch/xtensa/oprofile/backtrace.c | 158 ++-------------------------------
3 files changed, 182 insertions(+), 151 deletions(-)

diff --git a/arch/xtensa/include/asm/stacktrace.h b/arch/xtensa/include/asm/stacktrace.h
index 6a05fcb..fe06e8e 100644
--- a/arch/xtensa/include/asm/stacktrace.h
+++ b/arch/xtensa/include/asm/stacktrace.h
@@ -33,4 +33,12 @@ void walk_stackframe(unsigned long *sp,
int (*fn)(struct stackframe *frame, void *data),
void *data);

+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);
+void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
+ int (*ufn)(struct stackframe *frame, void *data),
+ void *data);
+
#endif /* _XTENSA_STACKTRACE_H */
diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c
index 7d2c317..7538d80 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),
diff --git a/arch/xtensa/oprofile/backtrace.c b/arch/xtensa/oprofile/backtrace.c
index 5f03a59..8f95203 100644
--- a/arch/xtensa/oprofile/backtrace.c
+++ b/arch/xtensa/oprofile/backtrace.c
@@ -2,168 +2,26 @@
* @file backtrace.c
*
* @remark Copyright 2008 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems 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>
+#include <asm/stacktrace.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)
+static int xtensa_backtrace_cb(struct stackframe *frame, void *data)
{
- 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;
+ oprofile_add_trace(frame->pc);
+ return 0;
}

void xtensa_backtrace(struct pt_regs * const regs, unsigned int depth)
{
if (user_mode(regs))
- xtensa_backtrace_user(regs, depth);
+ xtensa_backtrace_user(regs, depth, xtensa_backtrace_cb, NULL);
else
- xtensa_backtrace_kernel(regs, depth);
+ xtensa_backtrace_kernel(regs, depth, xtensa_backtrace_cb,
+ xtensa_backtrace_cb, NULL);
}
--
1.8.1.4


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