From 777a9f187effa0fd368bc38aa4d61e264cd1586d Mon Sep 17 00:00:00 2001 From: Jean Pihet Date: Mon, 3 Feb 2014 19:18:27 +0100 Subject: [PATCH 1/4] ARM64: perf: add support for perf registers API This patch implements the functions required for the perf registers API, allowing the perf tool to interface kernel register dumps with libunwind in order to provide userspace backtracing. Compat mode is also supported. Only the general purpose user space registers are exported, i.e.: PERF_REG_ARM_X0, ... PERF_REG_ARM_X28, PERF_REG_ARM_FP, PERF_REG_ARM_LR, PERF_REG_ARM_SP, PERF_REG_ARM_PC and not the PERF_REG_ARM_V* registers. Signed-off-by: Jean Pihet Acked-by: Will Deacon Signed-off-by: Catalin Marinas (cherry picked from commit 2ee0d7fd36a3f87bc5b29b1ec54ad6728deedb41) Signed-off-by: Mark Brown Conflicts: arch/arm64/kernel/Makefile --- arch/arm64/Kconfig | 2 ++ arch/arm64/include/asm/ptrace.h | 1 + arch/arm64/include/uapi/asm/Kbuild | 1 + arch/arm64/include/uapi/asm/perf_regs.h | 40 ++++++++++++++++++++++ arch/arm64/kernel/Makefile | 3 +- arch/arm64/kernel/perf_regs.c | 44 +++++++++++++++++++++++++ 6 files changed, 90 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/uapi/asm/perf_regs.h create mode 100644 arch/arm64/kernel/perf_regs.c diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 56b3f6d447ae..a11651758cc4 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -26,6 +26,8 @@ config ARM64 select HAVE_HW_BREAKPOINT if PERF_EVENTS select HAVE_MEMBLOCK select HAVE_PERF_EVENTS + select HAVE_PERF_REGS + select HAVE_PERF_USER_STACK_DUMP select IRQ_DOMAIN select MODULES_USE_ELF_RELA select NO_BOOTMEM diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 41a71ee4c3df..ba962130af1a 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -67,6 +67,7 @@ /* Architecturally defined mapping between AArch32 and AArch64 registers */ #define compat_usr(x) regs[(x)] +#define compat_fp regs[11] #define compat_sp regs[13] #define compat_lr regs[14] #define compat_sp_hyp regs[15] diff --git a/arch/arm64/include/uapi/asm/Kbuild b/arch/arm64/include/uapi/asm/Kbuild index e4b78bdca19e..942376d37d22 100644 --- a/arch/arm64/include/uapi/asm/Kbuild +++ b/arch/arm64/include/uapi/asm/Kbuild @@ -9,6 +9,7 @@ header-y += byteorder.h header-y += fcntl.h header-y += hwcap.h header-y += kvm_para.h +header-y += perf_regs.h header-y += param.h header-y += ptrace.h header-y += setup.h diff --git a/arch/arm64/include/uapi/asm/perf_regs.h b/arch/arm64/include/uapi/asm/perf_regs.h new file mode 100644 index 000000000000..172b8317ee49 --- /dev/null +++ b/arch/arm64/include/uapi/asm/perf_regs.h @@ -0,0 +1,40 @@ +#ifndef _ASM_ARM64_PERF_REGS_H +#define _ASM_ARM64_PERF_REGS_H + +enum perf_event_arm_regs { + PERF_REG_ARM64_X0, + PERF_REG_ARM64_X1, + PERF_REG_ARM64_X2, + PERF_REG_ARM64_X3, + PERF_REG_ARM64_X4, + PERF_REG_ARM64_X5, + PERF_REG_ARM64_X6, + PERF_REG_ARM64_X7, + PERF_REG_ARM64_X8, + PERF_REG_ARM64_X9, + PERF_REG_ARM64_X10, + PERF_REG_ARM64_X11, + PERF_REG_ARM64_X12, + PERF_REG_ARM64_X13, + PERF_REG_ARM64_X14, + PERF_REG_ARM64_X15, + PERF_REG_ARM64_X16, + PERF_REG_ARM64_X17, + PERF_REG_ARM64_X18, + PERF_REG_ARM64_X19, + PERF_REG_ARM64_X20, + PERF_REG_ARM64_X21, + PERF_REG_ARM64_X22, + PERF_REG_ARM64_X23, + PERF_REG_ARM64_X24, + PERF_REG_ARM64_X25, + PERF_REG_ARM64_X26, + PERF_REG_ARM64_X27, + PERF_REG_ARM64_X28, + PERF_REG_ARM64_X29, + PERF_REG_ARM64_LR, + PERF_REG_ARM64_SP, + PERF_REG_ARM64_PC, + PERF_REG_ARM64_MAX, +}; +#endif /* _ASM_ARM64_PERF_REGS_H */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 7b4b564961d4..db74e559d2ee 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -15,8 +15,9 @@ arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \ sys_compat.o arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o arm64-obj-$(CONFIG_SMP) += smp.o smp_spin_table.o smp_psci.o +arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o -arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o +arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o arm64-obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-y += $(arm64-obj-y) vdso/ diff --git a/arch/arm64/kernel/perf_regs.c b/arch/arm64/kernel/perf_regs.c new file mode 100644 index 000000000000..f2d6f0a36d63 --- /dev/null +++ b/arch/arm64/kernel/perf_regs.c @@ -0,0 +1,44 @@ +#include +#include +#include +#include +#include +#include + +u64 perf_reg_value(struct pt_regs *regs, int idx) +{ + if (WARN_ON_ONCE((u32)idx >= PERF_REG_ARM64_MAX)) + return 0; + + /* + * Compat (i.e. 32 bit) mode: + * - PC has been set in the pt_regs struct in kernel_entry, + * - Handle SP and LR here. + */ + if (compat_user_mode(regs)) { + if ((u32)idx == PERF_REG_ARM64_SP) + return regs->compat_sp; + if ((u32)idx == PERF_REG_ARM64_LR) + return regs->compat_lr; + } + + return regs->regs[idx]; +} + +#define REG_RESERVED (~((1ULL << PERF_REG_ARM64_MAX) - 1)) + +int perf_reg_validate(u64 mask) +{ + if (!mask || mask & REG_RESERVED) + return -EINVAL; + + return 0; +} + +u64 perf_reg_abi(struct task_struct *task) +{ + if (is_compat_thread(task_thread_info(task))) + return PERF_SAMPLE_REGS_ABI_32; + else + return PERF_SAMPLE_REGS_ABI_64; +} From e7926fd26b26935ebc33138b886e0eab0204da38 Mon Sep 17 00:00:00 2001 From: Jean Pihet Date: Mon, 3 Feb 2014 19:18:28 +0100 Subject: [PATCH 2/4] ARM64: perf: add support for frame pointer unwinding in compat mode When profiling a 32-bit application, user space callchain unwinding using the frame pointer is performed in compat mode. The code is taken over from the AARCH32 code and adapted to work on AARCH64. Signed-off-by: Jean Pihet Acked-by: Will Deacon Signed-off-by: Catalin Marinas (cherry picked from commit 23c7d70d55c6d963f225744cd1b996dee68c88d1) Signed-off-by: Mark Brown --- arch/arm64/kernel/perf_event.c | 75 ++++++++++++++++++++++++++++++---- 1 file changed, 67 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 60a41b9292a5..1b020200fffa 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -1336,8 +1336,8 @@ early_initcall(init_hw_perf_events); * Callchain handling code. */ struct frame_tail { - struct frame_tail __user *fp; - unsigned long lr; + struct frame_tail __user *fp; + unsigned long lr; } __attribute__((packed)); /* @@ -1374,22 +1374,80 @@ user_backtrace(struct frame_tail __user *tail, return buftail.fp; } +/* + * 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; +} + void perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) { - struct frame_tail __user *tail; - 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); - 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); + 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 { + /* 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); + } } /* @@ -1417,6 +1475,7 @@ void perf_callchain_kernel(struct perf_callchain_entry *entry, frame.fp = regs->regs[29]; frame.sp = regs->sp; frame.pc = regs->pc; + walk_stackframe(&frame, callchain_trace, entry); } From e9fb47bddd30616455f108efd89312b7ce06c742 Mon Sep 17 00:00:00 2001 From: Jean Pihet Date: Mon, 3 Feb 2014 19:18:29 +0100 Subject: [PATCH 3/4] ARM64: perf: support dwarf unwinding in compat mode Add support for unwinding using the dwarf information in compat mode. Using the correct user stack pointer allows perf to record the frames correctly in the native and compat modes. Note that although the dwarf frame unwinding works ok using libunwind in native mode (on ARMv7 & ARMv8), some changes are required to the libunwind code for the compat mode. Those changes are posted separately on the libunwind mailing list. Tested on ARMv8 platform with v8 and compat v7 binaries, the latter are statically built. Signed-off-by: Jean Pihet Acked-by: Will Deacon Signed-off-by: Catalin Marinas (cherry picked from commit 5f888a1d33c48900012e6b4c18296ce7c715dc6c) Signed-off-by: Mark Brown --- arch/arm64/include/asm/compat.h | 2 +- arch/arm64/include/asm/ptrace.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h index 899af807ef0f..7058eec269ab 100644 --- a/arch/arm64/include/asm/compat.h +++ b/arch/arm64/include/asm/compat.h @@ -214,7 +214,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr) return (u32)(unsigned long)uptr; } -#define compat_user_stack_pointer() (current_pt_regs()->compat_sp) +#define compat_user_stack_pointer() (user_stack_pointer(current_pt_regs())) static inline void __user *arch_compat_alloc_user_space(long len) { diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index ba962130af1a..b8e7cf199ce6 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -132,7 +132,7 @@ struct pt_regs { (!((regs)->pstate & PSR_F_BIT)) #define user_stack_pointer(regs) \ - ((regs)->sp) + (!compat_user_mode(regs)) ? ((regs)->sp) : ((regs)->compat_sp) /* * Are the current registers suitable for user mode? (used to maintain From 078511edeb9c152d10e75233b535d730918aa213 Mon Sep 17 00:00:00 2001 From: Mark Salter Date: Sat, 5 Apr 2014 15:25:49 +0100 Subject: [PATCH 4/4] arm64: fix !CONFIG_COMPAT build failures MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Recent arm64 builds using CONFIG_ARM64_64K_PAGES are failing with: arch/arm64/kernel/perf_regs.c: In function ‘perf_reg_abi’: arch/arm64/kernel/perf_regs.c:41:2: error: implicit declaration of function ‘is_compat_thread’ arch/arm64/kernel/perf_event.c:1398:2: error: unknown type name ‘compat_uptr_t’ This is due to some recent arm64 perf commits with compat support: commit 23c7d70d55c6d9: ARM64: perf: add support for frame pointer unwinding in compat mode commit 2ee0d7fd36a3f8: ARM64: perf: add support for perf registers API Those patches make the arm64 kernel unbuildable if CONFIG_COMPAT is not defined and CONFIG_ARM64_64K_PAGES depends on !CONFIG_COMPAT. This patch allows the arm64 kernel to build with and without CONFIG_COMPAT. Signed-off-by: Mark Salter Signed-off-by: Catalin Marinas (cherry picked from commit ff268ff7f32bf5388b7422f0c0773d88add23423) Signed-off-by: Mark Brown --- arch/arm64/kernel/perf_event.c | 4 ++++ arch/arm64/kernel/perf_regs.c | 2 ++ 2 files changed, 6 insertions(+) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 1b020200fffa..3047c6ad0a8d 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -1374,6 +1374,7 @@ user_backtrace(struct frame_tail __user *tail, 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 @@ -1418,6 +1419,7 @@ compat_user_backtrace(struct compat_frame_tail __user *tail, 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) @@ -1439,6 +1441,7 @@ void perf_callchain_user(struct perf_callchain_entry *entry, tail && !((unsigned long)tail & 0xf)) tail = user_backtrace(tail, entry); } else { +#ifdef CONFIG_COMPAT /* AARCH32 compat mode */ struct compat_frame_tail __user *tail; @@ -1447,6 +1450,7 @@ void perf_callchain_user(struct perf_callchain_entry *entry, while ((entry->nr < PERF_MAX_STACK_DEPTH) && tail && !((unsigned long)tail & 0x3)) tail = compat_user_backtrace(tail, entry); +#endif } } diff --git a/arch/arm64/kernel/perf_regs.c b/arch/arm64/kernel/perf_regs.c index f2d6f0a36d63..422ebd63b619 100644 --- a/arch/arm64/kernel/perf_regs.c +++ b/arch/arm64/kernel/perf_regs.c @@ -2,6 +2,8 @@ #include #include #include + +#include #include #include