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Merge Will Deacon's for-next/perf branch into for-next/core 

* will/for-next/perf:
  selftests: arm64: add test for unaligned/inexact watchpoint handling
  arm64: Allow hw watchpoint of length 3,5,6 and 7
  arm64: hw_breakpoint: Handle inexact watchpoint addresses
  arm64: Allow hw watchpoint at varied offset from base address
  hw_breakpoint: Allow watchpoint of length 3,5,6 and 7
This commit is contained in:
Catalin Marinas 2016-11-29 15:38:57 +00:00
parent 1650ac49c2 f43365ee17
commit 00cc2e0745
7 changed files with 373 additions and 44 deletions
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6
arch/arm64/include/asm/hw_breakpoint.h
View File

@ -77,7 +77,11 @@ static inline void decode_ctrl_reg(u32 reg,
/* Lengths */
#define ARM_BREAKPOINT_LEN_1 0x1
#define ARM_BREAKPOINT_LEN_2 0x3
#define ARM_BREAKPOINT_LEN_3 0x7
#define ARM_BREAKPOINT_LEN_4 0xf
#define ARM_BREAKPOINT_LEN_5 0x1f
#define ARM_BREAKPOINT_LEN_6 0x3f
#define ARM_BREAKPOINT_LEN_7 0x7f
#define ARM_BREAKPOINT_LEN_8 0xff
/* Kernel stepping */
@ -119,7 +123,7 @@ struct perf_event;
struct pmu;
extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
int *gen_len, int *gen_type);
int *gen_len, int *gen_type, int *offset);
extern int arch_check_bp_in_kernelspace(struct perf_event *bp);
extern int arch_validate_hwbkpt_settings(struct perf_event *bp);
extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,

155
arch/arm64/kernel/hw_breakpoint.c
View File

@ -317,9 +317,21 @@ static int get_hbp_len(u8 hbp_len)
case ARM_BREAKPOINT_LEN_2:
len_in_bytes = 2;
break;
case ARM_BREAKPOINT_LEN_3:
len_in_bytes = 3;
break;
case ARM_BREAKPOINT_LEN_4:
len_in_bytes = 4;
break;
case ARM_BREAKPOINT_LEN_5:
len_in_bytes = 5;
break;
case ARM_BREAKPOINT_LEN_6:
len_in_bytes = 6;
break;
case ARM_BREAKPOINT_LEN_7:
len_in_bytes = 7;
break;
case ARM_BREAKPOINT_LEN_8:
len_in_bytes = 8;
break;
@ -349,7 +361,7 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
* to generic breakpoint descriptions.
*/
int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
int *gen_len, int *gen_type)
int *gen_len, int *gen_type, int *offset)
{
/* Type */
switch (ctrl.type) {
@ -369,17 +381,33 @@ int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
return -EINVAL;
}
if (!ctrl.len)
return -EINVAL;
*offset = __ffs(ctrl.len);
/* Len */
switch (ctrl.len) {
switch (ctrl.len >> *offset) {
case ARM_BREAKPOINT_LEN_1:
*gen_len = HW_BREAKPOINT_LEN_1;
break;
case ARM_BREAKPOINT_LEN_2:
*gen_len = HW_BREAKPOINT_LEN_2;
break;
case ARM_BREAKPOINT_LEN_3:
*gen_len = HW_BREAKPOINT_LEN_3;
break;
case ARM_BREAKPOINT_LEN_4:
*gen_len = HW_BREAKPOINT_LEN_4;
break;
case ARM_BREAKPOINT_LEN_5:
*gen_len = HW_BREAKPOINT_LEN_5;
break;
case ARM_BREAKPOINT_LEN_6:
*gen_len = HW_BREAKPOINT_LEN_6;
break;
case ARM_BREAKPOINT_LEN_7:
*gen_len = HW_BREAKPOINT_LEN_7;
break;
case ARM_BREAKPOINT_LEN_8:
*gen_len = HW_BREAKPOINT_LEN_8;
break;
@ -423,9 +451,21 @@ static int arch_build_bp_info(struct perf_event *bp)
case HW_BREAKPOINT_LEN_2:
info->ctrl.len = ARM_BREAKPOINT_LEN_2;
break;
case HW_BREAKPOINT_LEN_3:
info->ctrl.len = ARM_BREAKPOINT_LEN_3;
break;
case HW_BREAKPOINT_LEN_4:
info->ctrl.len = ARM_BREAKPOINT_LEN_4;
break;
case HW_BREAKPOINT_LEN_5:
info->ctrl.len = ARM_BREAKPOINT_LEN_5;
break;
case HW_BREAKPOINT_LEN_6:
info->ctrl.len = ARM_BREAKPOINT_LEN_6;
break;
case HW_BREAKPOINT_LEN_7:
info->ctrl.len = ARM_BREAKPOINT_LEN_7;
break;
case HW_BREAKPOINT_LEN_8:
info->ctrl.len = ARM_BREAKPOINT_LEN_8;
break;
@ -517,18 +557,17 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
default:
return -EINVAL;
}
info->address &= ~alignment_mask;
info->ctrl.len <<= offset;
} else {
if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE)
alignment_mask = 0x3;
else
alignment_mask = 0x7;
if (info->address & alignment_mask)
return -EINVAL;
offset = info->address & alignment_mask;
}
info->address &= ~alignment_mask;
info->ctrl.len <<= offset;
/*
* Disallow per-task kernel breakpoints since these would
* complicate the stepping code.
@ -661,12 +700,47 @@ static int breakpoint_handler(unsigned long unused, unsigned int esr,
}
NOKPROBE_SYMBOL(breakpoint_handler);
/*
* Arm64 hardware does not always report a watchpoint hit address that matches
* one of the watchpoints set. It can also report an address "near" the
* watchpoint if a single instruction access both watched and unwatched
* addresses. There is no straight-forward way, short of disassembling the
* offending instruction, to map that address back to the watchpoint. This
* function computes the distance of the memory access from the watchpoint as a
* heuristic for the likelyhood that a given access triggered the watchpoint.
*
* See Section D2.10.5 "Determining the memory location that caused a Watchpoint
* exception" of ARMv8 Architecture Reference Manual for details.
*
* The function returns the distance of the address from the bytes watched by
* the watchpoint. In case of an exact match, it returns 0.
*/
static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
struct arch_hw_breakpoint_ctrl *ctrl)
{
u64 wp_low, wp_high;
u32 lens, lene;
lens = __ffs(ctrl->len);
lene = __fls(ctrl->len);
wp_low = val + lens;
wp_high = val + lene;
if (addr < wp_low)
return wp_low - addr;
else if (addr > wp_high)
return addr - wp_high;
else
return 0;
}
static int watchpoint_handler(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
int i, step = 0, *kernel_step, access;
int i, step = 0, *kernel_step, access, closest_match = 0;
u64 min_dist = -1, dist;
u32 ctrl_reg;
u64 val, alignment_mask;
u64 val;
struct perf_event *wp, **slots;
struct debug_info *debug_info;
struct arch_hw_breakpoint *info;
@ -675,35 +749,15 @@ static int watchpoint_handler(unsigned long addr, unsigned int esr,
slots = this_cpu_ptr(wp_on_reg);
debug_info = &current->thread.debug;
/*
* Find all watchpoints that match the reported address. If no exact
* match is found. Attribute the hit to the closest watchpoint.
*/
rcu_read_lock();
for (i = 0; i < core_num_wrps; ++i) {
rcu_read_lock();
wp = slots[i];
if (wp == NULL)
goto unlock;
info = counter_arch_bp(wp);
/* AArch32 watchpoints are either 4 or 8 bytes aligned. */
if (is_compat_task()) {
if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
alignment_mask = 0x7;
else
alignment_mask = 0x3;
} else {
alignment_mask = 0x7;
}
/* Check if the watchpoint value matches. */
val = read_wb_reg(AARCH64_DBG_REG_WVR, i);
if (val != (addr & ~alignment_mask))
goto unlock;
/* Possible match, check the byte address select to confirm. */
ctrl_reg = read_wb_reg(AARCH64_DBG_REG_WCR, i);
decode_ctrl_reg(ctrl_reg, &ctrl);
if (!((1 << (addr & alignment_mask)) & ctrl.len))
goto unlock;
continue;
/*
* Check that the access type matches.
@ -712,18 +766,41 @@ static int watchpoint_handler(unsigned long addr, unsigned int esr,
access = (esr & AARCH64_ESR_ACCESS_MASK) ? HW_BREAKPOINT_W :
HW_BREAKPOINT_R;
if (!(access & hw_breakpoint_type(wp)))
goto unlock;
continue;
/* Check if the watchpoint value and byte select match. */
val = read_wb_reg(AARCH64_DBG_REG_WVR, i);
ctrl_reg = read_wb_reg(AARCH64_DBG_REG_WCR, i);
decode_ctrl_reg(ctrl_reg, &ctrl);
dist = get_distance_from_watchpoint(addr, val, &ctrl);
if (dist < min_dist) {
min_dist = dist;
closest_match = i;
}
/* Is this an exact match? */
if (dist != 0)
continue;
info = counter_arch_bp(wp);
info->trigger = addr;
perf_bp_event(wp, regs);
/* Do we need to handle the stepping? */
if (is_default_overflow_handler(wp))
step = 1;
unlock:
rcu_read_unlock();
}
if (min_dist > 0 && min_dist != -1) {
/* No exact match found. */
wp = slots[closest_match];
info = counter_arch_bp(wp);
info->trigger = addr;
perf_bp_event(wp, regs);
/* Do we need to handle the stepping? */
if (is_default_overflow_handler(wp))
step = 1;
}
rcu_read_unlock();
if (!step)
return 0;

7
arch/arm64/kernel/ptrace.c
View File

@ -327,13 +327,13 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
struct arch_hw_breakpoint_ctrl ctrl,
struct perf_event_attr *attr)
{
int err, len, type, disabled = !ctrl.enabled;
int err, len, type, offset, disabled = !ctrl.enabled;
attr->disabled = disabled;
if (disabled)
return 0;
err = arch_bp_generic_fields(ctrl, &len, &type);
err = arch_bp_generic_fields(ctrl, &len, &type, &offset);
if (err)
return err;
@ -352,6 +352,7 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
attr->bp_len = len;
attr->bp_type = type;
attr->bp_addr += offset;
return 0;
}
@ -404,7 +405,7 @@ static int ptrace_hbp_get_addr(unsigned int note_type,
if (IS_ERR(bp))
return PTR_ERR(bp);
*addr = bp ? bp->attr.bp_addr : 0;
*addr = bp ? counter_arch_bp(bp)->address : 0;
return 0;
}

4
include/uapi/linux/hw_breakpoint.h
View File

@ -4,7 +4,11 @@
enum {
HW_BREAKPOINT_LEN_1 = 1,
HW_BREAKPOINT_LEN_2 = 2,
HW_BREAKPOINT_LEN_3 = 3,
HW_BREAKPOINT_LEN_4 = 4,
HW_BREAKPOINT_LEN_5 = 5,
HW_BREAKPOINT_LEN_6 = 6,
HW_BREAKPOINT_LEN_7 = 7,
HW_BREAKPOINT_LEN_8 = 8,
};

4
tools/include/uapi/linux/hw_breakpoint.h
View File

@ -4,7 +4,11 @@
enum {
HW_BREAKPOINT_LEN_1 = 1,
HW_BREAKPOINT_LEN_2 = 2,
HW_BREAKPOINT_LEN_3 = 3,
HW_BREAKPOINT_LEN_4 = 4,
HW_BREAKPOINT_LEN_5 = 5,
HW_BREAKPOINT_LEN_6 = 6,
HW_BREAKPOINT_LEN_7 = 7,
HW_BREAKPOINT_LEN_8 = 8,
};

5
tools/testing/selftests/breakpoints/Makefile
View File

@ -5,6 +5,9 @@ ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
ifeq ($(ARCH),x86)
TEST_PROGS := breakpoint_test
endif
ifeq ($(ARCH),aarch64)
TEST_PROGS := breakpoint_test_arm64
endif
TEST_PROGS += step_after_suspend_test
@ -13,4 +16,4 @@ all: $(TEST_PROGS)
include ../lib.mk
clean:
rm -fr breakpoint_test step_after_suspend_test
rm -fr breakpoint_test breakpoint_test_arm64 step_after_suspend_test

236
tools/testing/selftests/breakpoints/breakpoint_test_arm64.c Normal file
View File

@ -0,0 +1,236 @@
/*
* Copyright (C) 2016 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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.
*
* Original Code by Pavel Labath <labath@google.com>
*
* Code modified by Pratyush Anand <panand@redhat.com>
* for testing different byte select for each access size.
*
*/
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <sys/param.h>
#include <sys/uio.h>
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <elf.h>
#include <errno.h>
#include <signal.h>
#include "../kselftest.h"
static volatile uint8_t var[96] __attribute__((__aligned__(32)));
static void child(int size, int wr)
{
volatile uint8_t *addr = &var[32 + wr];
if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
perror("ptrace(PTRACE_TRACEME) failed");
_exit(1);
}
if (raise(SIGSTOP) != 0) {
perror("raise(SIGSTOP) failed");
_exit(1);
}
if ((uintptr_t) addr % size) {
perror("Wrong address write for the given size\n");
_exit(1);
}
switch (size) {
case 1:
*addr = 47;
break;
case 2:
*(uint16_t *)addr = 47;
break;
case 4:
*(uint32_t *)addr = 47;
break;
case 8:
*(uint64_t *)addr = 47;
break;
case 16:
__asm__ volatile ("stp x29, x30, %0" : "=m" (addr[0]));
break;
case 32:
__asm__ volatile ("stp q29, q30, %0" : "=m" (addr[0]));
break;
}
_exit(0);
}
static bool set_watchpoint(pid_t pid, int size, int wp)
{
const volatile uint8_t *addr = &var[32 + wp];
const int offset = (uintptr_t)addr % 8;
const unsigned int byte_mask = ((1 << size) - 1) << offset;
const unsigned int type = 2; /* Write */
const unsigned int enable = 1;
const unsigned int control = byte_mask << 5 | type << 3 | enable;
struct user_hwdebug_state dreg_state;
struct iovec iov;
memset(&dreg_state, 0, sizeof(dreg_state));
dreg_state.dbg_regs[0].addr = (uintptr_t)(addr - offset);
dreg_state.dbg_regs[0].ctrl = control;
iov.iov_base = &dreg_state;
iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) +
sizeof(dreg_state.dbg_regs[0]);
if (ptrace(PTRACE_SETREGSET, pid, NT_ARM_HW_WATCH, &iov) == 0)
return true;
if (errno == EIO) {
printf("ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) "
"not supported on this hardware\n");
ksft_exit_skip();
}
perror("ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) failed");
return false;
}
static bool run_test(int wr_size, int wp_size, int wr, int wp)
{
int status;
siginfo_t siginfo;
pid_t pid = fork();
pid_t wpid;
if (pid < 0) {
perror("fork() failed");
return false;
}
if (pid == 0)
child(wr_size, wr);
wpid = waitpid(pid, &status, __WALL);
if (wpid != pid) {
perror("waitpid() failed");
return false;
}
if (!WIFSTOPPED(status)) {
printf("child did not stop\n");
return false;
}
if (WSTOPSIG(status) != SIGSTOP) {
printf("child did not stop with SIGSTOP\n");
return false;
}
if (!set_watchpoint(pid, wp_size, wp))
return false;
if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
perror("ptrace(PTRACE_SINGLESTEP) failed");
return false;
}
alarm(3);
wpid = waitpid(pid, &status, __WALL);
if (wpid != pid) {
perror("waitpid() failed");
return false;
}
alarm(0);
if (WIFEXITED(status)) {
printf("child did not single-step\t");
return false;
}
if (!WIFSTOPPED(status)) {
printf("child did not stop\n");
return false;
}
if (WSTOPSIG(status) != SIGTRAP) {
printf("child did not stop with SIGTRAP\n");
return false;
}
if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
perror("ptrace(PTRACE_GETSIGINFO)");
return false;
}
if (siginfo.si_code != TRAP_HWBKPT) {
printf("Unexpected si_code %d\n", siginfo.si_code);
return false;
}
kill(pid, SIGKILL);
wpid = waitpid(pid, &status, 0);
if (wpid != pid) {
perror("waitpid() failed");
return false;
}
return true;
}
static void sigalrm(int sig)
{
}
int main(int argc, char **argv)
{
int opt;
bool succeeded = true;
struct sigaction act;
int wr, wp, size;
bool result;
act.sa_handler = sigalrm;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGALRM, &act, NULL);
for (size = 1; size <= 32; size = size*2) {
for (wr = 0; wr <= 32; wr = wr + size) {
for (wp = wr - size; wp <= wr + size; wp = wp + size) {
printf("Test size = %d write offset = %d watchpoint offset = %d\t", size, wr, wp);
result = run_test(size, MIN(size, 8), wr, wp);
if ((result && wr == wp) || (!result && wr != wp)) {
printf("[OK]\n");
ksft_inc_pass_cnt();
} else {
printf("[FAILED]\n");
ksft_inc_fail_cnt();
succeeded = false;
}
}
}
}
for (size = 1; size <= 32; size = size*2) {
printf("Test size = %d write offset = %d watchpoint offset = -8\t", size, -size);
if (run_test(size, 8, -size, -8)) {
printf("[OK]\n");
ksft_inc_pass_cnt();
} else {
printf("[FAILED]\n");
ksft_inc_fail_cnt();
succeeded = false;
}
}
ksft_print_cnts();
if (succeeded)
ksft_exit_pass();
else
ksft_exit_fail();
}