diff options
Diffstat (limited to 'arch/arm64/kernel/perf_callchain.c')
| -rw-r--r-- | arch/arm64/kernel/perf_callchain.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c new file mode 100644 index 000000000..58ae55d78 --- /dev/null +++ b/arch/arm64/kernel/perf_callchain.c @@ -0,0 +1,192 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * arm64 callchain support + * + * Copyright (C) 2015 ARM Limited + */ +#include <linux/perf_event.h> +#include <linux/uaccess.h> + +#include <asm/pointer_auth.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_ctx *entry) +{ + struct frame_tail buftail; + unsigned long err; + unsigned long lr; + + /* Also check accessibility of one struct frame_tail beyond */ + if (!access_ok(tail, sizeof(buftail))) + return NULL; + + pagefault_disable(); + err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); + pagefault_enable(); + + if (err) + return NULL; + + lr = ptrauth_strip_insn_pac(buftail.lr); + + perf_callchain_store(entry, 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_ctx *entry) +{ + struct compat_frame_tail buftail; + unsigned long err; + + /* Also check accessibility of one struct frame_tail beyond */ + if (!access_ok(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_ctx *entry, + struct pt_regs *regs) +{ + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && 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 < entry->max_stack && + 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 < entry->max_stack) && + 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 bool callchain_trace(void *data, unsigned long pc) +{ + struct perf_callchain_entry_ctx *entry = data; + perf_callchain_store(entry, pc); + return true; +} + +void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + struct stackframe frame; + + if (guest_cbs && guest_cbs->is_in_guest()) { + /* We don't support guest os callchain now */ + return; + } + + start_backtrace(&frame, regs->regs[29], regs->pc); + walk_stackframe(current, &frame, callchain_trace, entry); +} + +unsigned long perf_instruction_pointer(struct pt_regs *regs) +{ + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && guest_cbs->is_in_guest()) + return guest_cbs->get_guest_ip(); + + return instruction_pointer(regs); +} + +unsigned long perf_misc_flags(struct pt_regs *regs) +{ + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + int misc = 0; + + if (guest_cbs && guest_cbs->is_in_guest()) { + if (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; +} |