diff options
Diffstat (limited to 'tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c')
| -rw-r--r-- | tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c new file mode 100644 index 000000000000..a0a0b9bb5854 --- /dev/null +++ b/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c @@ -0,0 +1,445 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#include <asm/unistd.h> +#include <linux/hw_breakpoint.h> +#include <linux/ptrace.h> +#include <memory.h> +#include <stdlib.h> +#include <sys/wait.h> + +#include "utils.h" + +/* + * Child subroutine that performs a load on the address, then traps + */ +void same_watch_addr_child(unsigned long *addr); + +/* Address of the ld instruction in same_watch_addr_child() */ +extern char same_watch_addr_load[]; + +/* Address of the end trap instruction in same_watch_addr_child() */ +extern char same_watch_addr_trap[]; + +/* + * Child subroutine that performs a load on the first address, then a load on + * the second address (with no instructions separating this from the first + * load), then traps. + */ +void perf_then_ptrace_child(unsigned long *first_addr, unsigned long *second_addr); + +/* Address of the first ld instruction in perf_then_ptrace_child() */ +extern char perf_then_ptrace_load1[]; + +/* Address of the second ld instruction in perf_then_ptrace_child() */ +extern char perf_then_ptrace_load2[]; + +/* Address of the end trap instruction in perf_then_ptrace_child() */ +extern char perf_then_ptrace_trap[]; + +static inline long sys_ptrace(long request, pid_t pid, unsigned long addr, unsigned long data) +{ + return syscall(__NR_ptrace, request, pid, addr, data); +} + +static long ptrace_traceme(void) +{ + return sys_ptrace(PTRACE_TRACEME, 0, 0, 0); +} + +static long ptrace_getregs(pid_t pid, struct pt_regs *result) +{ + return sys_ptrace(PTRACE_GETREGS, pid, 0, (unsigned long)result); +} + +static long ptrace_setregs(pid_t pid, struct pt_regs *result) +{ + return sys_ptrace(PTRACE_SETREGS, pid, 0, (unsigned long)result); +} + +static long ptrace_cont(pid_t pid, long signal) +{ + return sys_ptrace(PTRACE_CONT, pid, 0, signal); +} + +static long ptrace_singlestep(pid_t pid, long signal) +{ + return sys_ptrace(PTRACE_SINGLESTEP, pid, 0, signal); +} + +static long ppc_ptrace_gethwdbginfo(pid_t pid, struct ppc_debug_info *dbginfo) +{ + return sys_ptrace(PPC_PTRACE_GETHWDBGINFO, pid, 0, (unsigned long)dbginfo); +} + +static long ppc_ptrace_sethwdbg(pid_t pid, struct ppc_hw_breakpoint *bp_info) +{ + return sys_ptrace(PPC_PTRACE_SETHWDEBUG, pid, 0, (unsigned long)bp_info); +} + +static long ppc_ptrace_delhwdbg(pid_t pid, int bp_id) +{ + return sys_ptrace(PPC_PTRACE_DELHWDEBUG, pid, 0L, bp_id); +} + +static long ptrace_getreg_pc(pid_t pid, void **pc) +{ + struct pt_regs regs; + long err; + + err = ptrace_getregs(pid, ®s); + if (err) + return err; + + *pc = (void *)regs.nip; + + return 0; +} + +static long ptrace_setreg_pc(pid_t pid, void *pc) +{ + struct pt_regs regs; + long err; + + err = ptrace_getregs(pid, ®s); + if (err) + return err; + + regs.nip = (unsigned long)pc; + + err = ptrace_setregs(pid, ®s); + if (err) + return err; + + return 0; +} + +static int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu, + int group_fd, unsigned long flags) +{ + return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags); +} + +static void perf_user_event_attr_set(struct perf_event_attr *attr, void *addr, u64 len) +{ + memset(attr, 0, sizeof(struct perf_event_attr)); + + attr->type = PERF_TYPE_BREAKPOINT; + attr->size = sizeof(struct perf_event_attr); + attr->bp_type = HW_BREAKPOINT_R; + attr->bp_addr = (u64)addr; + attr->bp_len = len; + attr->exclude_kernel = 1; + attr->exclude_hv = 1; +} + +static int perf_watchpoint_open(pid_t child_pid, void *addr, u64 len) +{ + struct perf_event_attr attr; + + perf_user_event_attr_set(&attr, addr, len); + return perf_event_open(&attr, child_pid, -1, -1, 0); +} + +static int perf_read_counter(int perf_fd, u64 *count) +{ + /* + * A perf counter is retrieved by the read() syscall. It contains + * the current count as 8 bytes that are interpreted as a u64 + */ + ssize_t len = read(perf_fd, count, sizeof(*count)); + + if (len != sizeof(*count)) + return -1; + + return 0; +} + +static void ppc_ptrace_init_breakpoint(struct ppc_hw_breakpoint *info, + int type, void *addr, int len) +{ + info->version = 1; + info->trigger_type = type; + info->condition_mode = PPC_BREAKPOINT_CONDITION_NONE; + info->addr = (u64)addr; + info->addr2 = (u64)addr + len; + info->condition_value = 0; + if (!len) + info->addr_mode = PPC_BREAKPOINT_MODE_EXACT; + else + info->addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE; +} + +/* + * Checks if we can place at least 2 watchpoints on the child process + */ +static int check_watchpoints(pid_t pid) +{ + struct ppc_debug_info dbginfo; + + FAIL_IF_MSG(ppc_ptrace_gethwdbginfo(pid, &dbginfo), "PPC_PTRACE_GETHWDBGINFO failed"); + SKIP_IF_MSG(dbginfo.num_data_bps <= 1, "Not enough data watchpoints (need at least 2)"); + + return 0; +} + +/* + * Wrapper around a plain fork() call that sets up the child for + * ptrace-ing. Both the parent and child return from this, though + * the child is stopped until ptrace_cont(pid) is run by the parent. + */ +static int ptrace_fork_child(pid_t *pid) +{ + int status; + + *pid = fork(); + + if (*pid < 0) + FAIL_IF_MSG(1, "Failed to fork child"); + + if (!*pid) { + FAIL_IF_EXIT_MSG(ptrace_traceme(), "PTRACE_TRACEME failed"); + FAIL_IF_EXIT_MSG(raise(SIGSTOP), "Child failed to raise SIGSTOP"); + } else { + /* Synchronise on child SIGSTOP */ + FAIL_IF_MSG(waitpid(*pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + } + + return 0; +} + +/* + * Tests the interaction between ptrace and perf watching the same data. + * + * We expect ptrace to take 'priority', as it is has before-execute + * semantics. + * + * The perf counter should not be incremented yet because perf has after-execute + * semantics. E.g., if ptrace changes the child PC, we don't even execute the + * instruction at all. + * + * When the child is stopped for ptrace, we test both continue and single step. + * Both should increment the perf counter. We also test changing the PC somewhere + * different and stepping, which should not increment the perf counter. + */ +int same_watch_addr_test(void) +{ + struct ppc_hw_breakpoint bp_info; /* ptrace breakpoint info */ + int bp_id; /* Breakpoint handle of ptrace watchpoint */ + int perf_fd; /* File descriptor of perf performance counter */ + u64 perf_count; /* Most recently fetched perf performance counter value */ + pid_t pid; /* PID of child process */ + void *pc; /* Most recently fetched child PC value */ + int status; /* Stop status of child after waitpid */ + unsigned long value; /* Dummy value to be read/written to by child */ + int err; + + err = ptrace_fork_child(&pid); + if (err) + return err; + + if (!pid) { + same_watch_addr_child(&value); + exit(1); + } + + err = check_watchpoints(pid); + if (err) + return err; + + /* Place a perf watchpoint counter on value */ + perf_fd = perf_watchpoint_open(pid, &value, sizeof(value)); + FAIL_IF_MSG(perf_fd < 0, "Failed to open perf performance counter"); + + /* Place a ptrace watchpoint on value */ + ppc_ptrace_init_breakpoint(&bp_info, PPC_BREAKPOINT_TRIGGER_READ, &value, sizeof(value)); + bp_id = ppc_ptrace_sethwdbg(pid, &bp_info); + FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint"); + + /* Let the child run. It should stop on the ptrace watchpoint */ + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load instruction"); + + /* + * We stopped before executing the load, so perf should not have + * recorded any events yet + */ + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 0, "perf recorded unexpected event"); + + /* Single stepping over the load should increment the perf counter */ + FAIL_IF_MSG(ptrace_singlestep(pid, 0), "Failed to single step child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_load + 4, "Failed to single step load instruction"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 1, "perf counter did not increment"); + + /* + * Set up a ptrace watchpoint on the value again and trigger it. + * The perf counter should not have incremented because we do not + * execute the load yet. + */ + FAIL_IF_MSG(ppc_ptrace_delhwdbg(pid, bp_id), "Failed to remove old ptrace watchpoint"); + bp_id = ppc_ptrace_sethwdbg(pid, &bp_info); + FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint"); + FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC"); + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load trap"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 1, "perf counter should not have changed"); + + /* Continuing over the load should increment the perf counter */ + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 2, "perf counter did not increment"); + + /* + * If we set the child PC back to the load instruction, then continue, + * we should reach the end trap (because ptrace is one-shot) and have + * another perf event. + */ + FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC"); + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 3, "perf counter did not increment"); + + /* + * If we set the child PC back to the load instruction, set a ptrace + * watchpoint on the load, then continue, we should immediately get + * the ptrace trap without incrementing the perf counter + */ + FAIL_IF_MSG(ppc_ptrace_delhwdbg(pid, bp_id), "Failed to remove old ptrace watchpoint"); + bp_id = ppc_ptrace_sethwdbg(pid, &bp_info); + FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint"); + FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC"); + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load instruction"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 3, "perf counter should not have changed"); + + /* + * If we change the PC while stopped on the load instruction, we should + * not increment the perf counter (because ptrace is before-execute, + * perf is after-execute). + */ + FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load + 4), "Failed to set child PC"); + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap"); + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 3, "perf counter should not have changed"); + + /* Clean up child */ + FAIL_IF_MSG(kill(pid, SIGKILL) != 0, "Failed to kill child"); + + return 0; +} + +/* + * Tests the interaction between ptrace and perf when: + * 1. perf watches a value + * 2. ptrace watches a different value + * 3. The perf value is read, then the ptrace value is read immediately after + * + * A breakpoint implementation may accidentally misattribute/skip one of + * the ptrace or perf handlers, as interrupt based work is done after perf + * and before ptrace. + * + * We expect the perf counter to increment before the ptrace watchpoint + * triggers. + */ +int perf_then_ptrace_test(void) +{ + struct ppc_hw_breakpoint bp_info; /* ptrace breakpoint info */ + int bp_id; /* Breakpoint handle of ptrace watchpoint */ + int perf_fd; /* File descriptor of perf performance counter */ + u64 perf_count; /* Most recently fetched perf performance counter value */ + pid_t pid; /* PID of child process */ + void *pc; /* Most recently fetched child PC value */ + int status; /* Stop status of child after waitpid */ + unsigned long perf_value; /* Dummy value to be watched by perf */ + unsigned long ptrace_value; /* Dummy value to be watched by ptrace */ + int err; + + err = ptrace_fork_child(&pid); + if (err) + return err; + + /* + * If we are the child, run a subroutine that reads the perf value, + * then reads the ptrace value with consecutive load instructions + */ + if (!pid) { + perf_then_ptrace_child(&perf_value, &ptrace_value); + exit(0); + } + + err = check_watchpoints(pid); + if (err) + return err; + + /* Place a perf watchpoint counter */ + perf_fd = perf_watchpoint_open(pid, &perf_value, sizeof(perf_value)); + FAIL_IF_MSG(perf_fd < 0, "Failed to open perf performance counter"); + + /* Place a ptrace watchpoint */ + ppc_ptrace_init_breakpoint(&bp_info, PPC_BREAKPOINT_TRIGGER_READ, + &ptrace_value, sizeof(ptrace_value)); + bp_id = ppc_ptrace_sethwdbg(pid, &bp_info); + FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint"); + + /* Let the child run. It should stop on the ptrace watchpoint */ + FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child"); + + FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child"); + FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped"); + FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC"); + FAIL_IF_MSG(pc != perf_then_ptrace_load2, "Child did not stop on ptrace load"); + + /* perf should have recorded the first load */ + FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter"); + FAIL_IF_MSG(perf_count != 1, "perf counter did not increment"); + + /* Clean up child */ + FAIL_IF_MSG(kill(pid, SIGKILL) != 0, "Failed to kill child"); + + return 0; +} + +int main(int argc, char *argv[]) +{ + int err = 0; + + err |= test_harness(same_watch_addr_test, "same_watch_addr"); + err |= test_harness(perf_then_ptrace_test, "perf_then_ptrace"); + + return err; +} |