// SPDX-License-Identifier: GPL-2.0 #include <linux/compiler.h> #include <linux/types.h> #include <linux/zalloc.h> #include <inttypes.h> #include <limits.h> #include <unistd.h> #include "tests.h" #include "debug.h" #include "machine.h" #include "event.h" #include "../util/unwind.h" #include "perf_regs.h" #include "map.h" #include "symbol.h" #include "thread.h" #include "callchain.h" #include "util/synthetic-events.h" /* For bsearch. We try to unwind functions in shared object. */ #include <stdlib.h> /* * The test will assert frames are on the stack but tail call optimizations lose * the frame of the caller. Clang can disable this optimization on a called * function but GCC currently (11/2020) lacks this attribute. The barrier is * used to inhibit tail calls in these cases. */ #ifdef __has_attribute #if __has_attribute(disable_tail_calls) #define NO_TAIL_CALL_ATTRIBUTE __attribute__((disable_tail_calls)) #define NO_TAIL_CALL_BARRIER #endif #endif #ifndef NO_TAIL_CALL_ATTRIBUTE #define NO_TAIL_CALL_ATTRIBUTE #define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory"); #endif static int mmap_handler(struct perf_tool *tool __maybe_unused, union perf_event *event, struct perf_sample *sample, struct machine *machine) { return machine__process_mmap2_event(machine, event, sample); } static int init_live_machine(struct machine *machine) { union perf_event event; pid_t pid = getpid(); memset(&event, 0, sizeof(event)); return perf_event__synthesize_mmap_events(NULL, &event, pid, pid, mmap_handler, machine, true); } /* * We need to keep these functions global, despite the * fact that they are used only locally in this object, * in order to keep them around even if the binary is * stripped. If they are gone, the unwind check for * symbol fails. */ int test_dwarf_unwind__thread(struct thread *thread); int test_dwarf_unwind__compare(void *p1, void *p2); int test_dwarf_unwind__krava_3(struct thread *thread); int test_dwarf_unwind__krava_2(struct thread *thread); int test_dwarf_unwind__krava_1(struct thread *thread); #define MAX_STACK 8 static int unwind_entry(struct unwind_entry *entry, void *arg) { unsigned long *cnt = (unsigned long *) arg; char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL; static const char *funcs[MAX_STACK] = { "test__arch_unwind_sample", "test_dwarf_unwind__thread", "test_dwarf_unwind__compare", "bsearch", "test_dwarf_unwind__krava_3", "test_dwarf_unwind__krava_2", "test_dwarf_unwind__krava_1", "test__dwarf_unwind" }; /* * The funcs[MAX_STACK] array index, based on the * callchain order setup. */ int idx = callchain_param.order == ORDER_CALLER ? MAX_STACK - *cnt - 1 : *cnt; if (*cnt >= MAX_STACK) { pr_debug("failed: crossed the max stack value %d\n", MAX_STACK); return -1; } if (!symbol) { pr_debug("failed: got unresolved address 0x%" PRIx64 "\n", entry->ip); return -1; } (*cnt)++; pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n", symbol, entry->ip, funcs[idx]); return strcmp((const char *) symbol, funcs[idx]); } NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__thread(struct thread *thread) { struct perf_sample sample; unsigned long cnt = 0; int err = -1; memset(&sample, 0, sizeof(sample)); if (test__arch_unwind_sample(&sample, thread)) { pr_debug("failed to get unwind sample\n"); goto out; } err = unwind__get_entries(unwind_entry, &cnt, thread, &sample, MAX_STACK, false); if (err) pr_debug("unwind failed\n"); else if (cnt != MAX_STACK) { pr_debug("got wrong number of stack entries %lu != %d\n", cnt, MAX_STACK); err = -1; } out: zfree(&sample.user_stack.data); zfree(&sample.user_regs.regs); return err; } static int global_unwind_retval = -INT_MAX; NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__compare(void *p1, void *p2) { /* Any possible value should be 'thread' */ struct thread *thread = *(struct thread **)p1; if (global_unwind_retval == -INT_MAX) { /* Call unwinder twice for both callchain orders. */ callchain_param.order = ORDER_CALLER; global_unwind_retval = test_dwarf_unwind__thread(thread); if (!global_unwind_retval) { callchain_param.order = ORDER_CALLEE; global_unwind_retval = test_dwarf_unwind__thread(thread); } } return p1 - p2; } NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_3(struct thread *thread) { struct thread *array[2] = {thread, thread}; void *fp = &bsearch; /* * make _bsearch a volatile function pointer to * prevent potential optimization, which may expand * bsearch and call compare directly from this function, * instead of libc shared object. */ void *(*volatile _bsearch)(void *, void *, size_t, size_t, int (*)(void *, void *)); _bsearch = fp; _bsearch(array, &thread, 2, sizeof(struct thread **), test_dwarf_unwind__compare); return global_unwind_retval; } NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_2(struct thread *thread) { int ret; ret = test_dwarf_unwind__krava_3(thread); NO_TAIL_CALL_BARRIER; return ret; } NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_1(struct thread *thread) { int ret; ret = test_dwarf_unwind__krava_2(thread); NO_TAIL_CALL_BARRIER; return ret; } static int test__dwarf_unwind(struct test_suite *test __maybe_unused, int subtest __maybe_unused) { struct machine *machine; struct thread *thread; int err = -1; machine = machine__new_host(); if (!machine) { pr_err("Could not get machine\n"); return -1; } if (machine__create_kernel_maps(machine)) { pr_err("Failed to create kernel maps\n"); return -1; } callchain_param.record_mode = CALLCHAIN_DWARF; dwarf_callchain_users = true; if (init_live_machine(machine)) { pr_err("Could not init machine\n"); goto out; } if (verbose > 1) machine__fprintf(machine, stderr); thread = machine__find_thread(machine, getpid(), getpid()); if (!thread) { pr_err("Could not get thread\n"); goto out; } err = test_dwarf_unwind__krava_1(thread); thread__put(thread); out: machine__delete_threads(machine); machine__delete(machine); return err; } DEFINE_SUITE("Test dwarf unwind", dwarf_unwind);