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 <jean.pihet@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 140cd1a..507ab6e 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -39,6 +39,8 @@ config ARM64
        select HAVE_MEMBLOCK
        select HAVE_PATA_PLATFORM
        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 5233966..35ff2f9 100644 (file)
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -68,6 +68,7 @@
 
 /* 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 e4b78bd..942376d 100644 (file)
--- 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 (file)
index 0000000..172b831
--- /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 cfee827..7d811d9 100644 (file)
--- 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-$(CONFIG_SMP)                        += smp.o smp_spin_table.o topology.o
+arm64-obj-$(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
 arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND)  += sleep.o suspend.o
 arm64-obj-$(CONFIG_JUMP_LABEL)         += jump_label.o

diff --git a/arch/arm64/kernel/perf_regs.c b/arch/arm64/kernel/perf_regs.c
new file mode 100644 (file)
index 0000000..f2d6f0a
--- /dev/null
+++ b/arch/arm64/kernel/perf_regs.c
@@ -0,0 +1,44 @@
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/bug.h>
+#include <asm/perf_regs.h>
+#include <asm/ptrace.h>
+
+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;
+}