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- /*
- * arm64 callchain support
- *
- * Copyright (C) 2015 ARM Limited
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
- #include <linux/perf_event.h>
- #include <linux/uaccess.h>
- #include <asm/stacktrace.h>
- struct frame_tail {
- struct frame_tail __user *fp;
- unsigned long lr;
- } __attribute__((packed));
- /*
- * Get the return address for a single stackframe and return a pointer to the
- * next frame tail.
- */
- static struct frame_tail __user *
- user_backtrace(struct frame_tail __user *tail,
- struct perf_callchain_entry *entry)
- {
- struct frame_tail buftail;
- unsigned long err;
- /* Also check accessibility of one struct frame_tail beyond */
- if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
- return NULL;
- pagefault_disable();
- err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
- pagefault_enable();
- if (err)
- return NULL;
- perf_callchain_store(entry, buftail.lr);
- /*
- * Frame pointers should strictly progress back up the stack
- * (towards higher addresses).
- */
- if (tail >= buftail.fp)
- return NULL;
- return buftail.fp;
- }
- #ifdef CONFIG_COMPAT
- /*
- * The registers we're interested in are at the end of the variable
- * length saved register structure. The fp points at the end of this
- * structure so the address of this struct is:
- * (struct compat_frame_tail *)(xxx->fp)-1
- *
- * This code has been adapted from the ARM OProfile support.
- */
- struct compat_frame_tail {
- compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */
- u32 sp;
- u32 lr;
- } __attribute__((packed));
- static struct compat_frame_tail __user *
- compat_user_backtrace(struct compat_frame_tail __user *tail,
- struct perf_callchain_entry *entry)
- {
- struct compat_frame_tail buftail;
- unsigned long err;
- /* Also check accessibility of one struct frame_tail beyond */
- if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
- return NULL;
- pagefault_disable();
- err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
- pagefault_enable();
- if (err)
- return NULL;
- perf_callchain_store(entry, buftail.lr);
- /*
- * Frame pointers should strictly progress back up the stack
- * (towards higher addresses).
- */
- if (tail + 1 >= (struct compat_frame_tail __user *)
- compat_ptr(buftail.fp))
- return NULL;
- return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
- }
- #endif /* CONFIG_COMPAT */
- void perf_callchain_user(struct perf_callchain_entry *entry,
- struct pt_regs *regs)
- {
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- /* We don't support guest os callchain now */
- return;
- }
- perf_callchain_store(entry, regs->pc);
- if (!compat_user_mode(regs)) {
- /* AARCH64 mode */
- struct frame_tail __user *tail;
- tail = (struct frame_tail __user *)regs->regs[29];
- while (entry->nr < PERF_MAX_STACK_DEPTH &&
- tail && !((unsigned long)tail & 0xf))
- tail = user_backtrace(tail, entry);
- } else {
- #ifdef CONFIG_COMPAT
- /* AARCH32 compat mode */
- struct compat_frame_tail __user *tail;
- tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
- while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
- tail && !((unsigned long)tail & 0x3))
- tail = compat_user_backtrace(tail, entry);
- #endif
- }
- }
- /*
- * Gets called by walk_stackframe() for every stackframe. This will be called
- * whist unwinding the stackframe and is like a subroutine return so we use
- * the PC.
- */
- static int callchain_trace(struct stackframe *frame, void *data)
- {
- struct perf_callchain_entry *entry = data;
- perf_callchain_store(entry, frame->pc);
- return 0;
- }
- void perf_callchain_kernel(struct perf_callchain_entry *entry,
- struct pt_regs *regs)
- {
- struct stackframe frame;
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- /* We don't support guest os callchain now */
- return;
- }
- frame.fp = regs->regs[29];
- frame.sp = regs->sp;
- frame.pc = regs->pc;
- walk_stackframe(&frame, callchain_trace, entry);
- }
- unsigned long perf_instruction_pointer(struct pt_regs *regs)
- {
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
- return perf_guest_cbs->get_guest_ip();
- return instruction_pointer(regs);
- }
- unsigned long perf_misc_flags(struct pt_regs *regs)
- {
- int misc = 0;
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- if (perf_guest_cbs->is_user_mode())
- misc |= PERF_RECORD_MISC_GUEST_USER;
- else
- misc |= PERF_RECORD_MISC_GUEST_KERNEL;
- } else {
- if (user_mode(regs))
- misc |= PERF_RECORD_MISC_USER;
- else
- misc |= PERF_RECORD_MISC_KERNEL;
- }
- return misc;
- }
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