Commit e427054a authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'x86-fgraph-bpf-fix-orc-stack-unwind-from-return-probe' 

Jiri Olsa says:

====================
x86/fgraph,bpf: Fix ORC stack unwind from return probe

sending fix for ORC stack unwind issue reported in here [1], where
the ORC unwinder won't go pass the return_to_handler function and
we get no stacktrace.

Sending fix for that together with unrelated stacktrace fix (patch 1),
so the attached test can work properly.

It's based on:
  https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
  probes/for-next

v1: https://lore.kernel.org/bpf/20251027131354.1984006-1-jolsa@kernel.org/
v2: https://lore.kernel.org/bpf/20251103220924.36371-3-jolsa@kernel.org/

v3 changes:
- fix assert condition in test

thanks,
jirka

[1] https://lore.kernel.org/bpf/aObSyt3qOnS_BMcy@krava/


====================

Acked-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Link: https://patch.msgid.link/20251104215405.168643-1-jolsa@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 44e8f13f 3490d299

arch/x86/events/core.c

+5 −5
Original line number Diff line number Diff line
@@ -2789,13 +2789,13 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re 
		return;

	}



	if (perf_hw_regs(regs)) {

		if (perf_callchain_store(entry, regs->ip))

			return;



	if (perf_hw_regs(regs))

		unwind_start(&state, current, regs, NULL);

	else

	} else {

		unwind_start(&state, current, NULL, (void *)regs->sp);

	}



	for (; !unwind_done(&state); unwind_next_frame(&state)) {

		addr = unwind_get_return_address(&state);

arch/x86/include/asm/ftrace.h

+5 −0
Original line number Diff line number Diff line
@@ -56,6 +56,11 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) 
	return &arch_ftrace_regs(fregs)->regs;

}



#define arch_ftrace_partial_regs(regs) do {	\

	regs->flags &= ~X86_EFLAGS_FIXED;	\

	regs->cs = __KERNEL_CS;			\

} while (0)



#define arch_ftrace_fill_perf_regs(fregs, _regs) do {	\

		(_regs)->ip = arch_ftrace_regs(fregs)->regs.ip;		\

		(_regs)->sp = arch_ftrace_regs(fregs)->regs.sp;		\

arch/x86/kernel/ftrace_64.S

+7 −1
Original line number Diff line number Diff line
@@ -354,12 +354,17 @@ SYM_CODE_START(return_to_handler) 
	UNWIND_HINT_UNDEFINED

	ANNOTATE_NOENDBR



	/* Restore return_to_handler value that got eaten by previous ret instruction. */

	subq $8, %rsp

	UNWIND_HINT_FUNC



	/* Save ftrace_regs for function exit context  */

	subq $(FRAME_SIZE), %rsp



	movq %rax, RAX(%rsp)

	movq %rdx, RDX(%rsp)

	movq %rbp, RBP(%rsp)

	movq %rsp, RSP(%rsp)

	movq %rsp, %rdi



	call ftrace_return_to_handler
@@ -368,7 +373,8 @@ SYM_CODE_START(return_to_handler) 
	movq RDX(%rsp), %rdx

	movq RAX(%rsp), %rax



	addq $(FRAME_SIZE), %rsp

	addq $(FRAME_SIZE) + 8, %rsp



	/*

	 * Jump back to the old return address. This cannot be JMP_NOSPEC rdi

	 * since IBT would demand that contain ENDBR, which simply isn't so for

include/linux/ftrace.h

+9 −1
Original line number Diff line number Diff line
@@ -193,6 +193,10 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs 
#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \

	defined(CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS)



#ifndef arch_ftrace_partial_regs

#define arch_ftrace_partial_regs(regs) do {} while (0)

#endif



static __always_inline struct pt_regs *

ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)

{
@@ -202,7 +206,11 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs) 
	 * Since arch_ftrace_get_regs() will check some members and may return

	 * NULL, we can not use it.

	 */

	return &arch_ftrace_regs(fregs)->regs;

	regs = &arch_ftrace_regs(fregs)->regs;



	/* Allow arch specific updates to regs. */

	arch_ftrace_partial_regs(regs);

	return regs;

}



#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */

tools/testing/selftests/bpf/prog_tests/stacktrace_ips.c

0 → 100644
+150 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include "stacktrace_ips.skel.h"



#ifdef __x86_64__

static int check_stacktrace_ips(int fd, __u32 key, int cnt, ...)

{

	__u64 ips[PERF_MAX_STACK_DEPTH];

	struct ksyms *ksyms = NULL;

	int i, err = 0;

	va_list args;



	/* sorted by addr */

	ksyms = load_kallsyms_local();

	if (!ASSERT_OK_PTR(ksyms, "load_kallsyms_local"))

		return -1;



	/* unlikely, but... */

	if (!ASSERT_LT(cnt, PERF_MAX_STACK_DEPTH, "check_max"))

		return -1;



	err = bpf_map_lookup_elem(fd, &key, ips);

	if (err)

		goto out;



	/*

	 * Compare all symbols provided via arguments with stacktrace ips,

	 * and their related symbol addresses.t

	 */

	va_start(args, cnt);



	for (i = 0; i < cnt; i++) {

		unsigned long val;

		struct ksym *ksym;



		val = va_arg(args, unsigned long);

		ksym = ksym_search_local(ksyms, ips[i]);

		if (!ASSERT_OK_PTR(ksym, "ksym_search_local"))

			break;

		ASSERT_EQ(ksym->addr, val, "stack_cmp");

	}



	va_end(args);



out:

	free_kallsyms_local(ksyms);

	return err;

}



static void test_stacktrace_ips_kprobe_multi(bool retprobe)

{

	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts,

		.retprobe = retprobe

	);

	LIBBPF_OPTS(bpf_test_run_opts, topts);

	struct stacktrace_ips *skel;



	skel = stacktrace_ips__open_and_load();

	if (!ASSERT_OK_PTR(skel, "stacktrace_ips__open_and_load"))

		return;



	if (!skel->kconfig->CONFIG_UNWINDER_ORC) {

		test__skip();

		goto cleanup;

	}



	skel->links.kprobe_multi_test = bpf_program__attach_kprobe_multi_opts(

							skel->progs.kprobe_multi_test,

							"bpf_testmod_stacktrace_test", &opts);

	if (!ASSERT_OK_PTR(skel->links.kprobe_multi_test, "bpf_program__attach_kprobe_multi_opts"))

		goto cleanup;



	trigger_module_test_read(1);



	load_kallsyms();



	check_stacktrace_ips(bpf_map__fd(skel->maps.stackmap), skel->bss->stack_key, 4,

			     ksym_get_addr("bpf_testmod_stacktrace_test_3"),

			     ksym_get_addr("bpf_testmod_stacktrace_test_2"),

			     ksym_get_addr("bpf_testmod_stacktrace_test_1"),

			     ksym_get_addr("bpf_testmod_test_read"));



cleanup:

	stacktrace_ips__destroy(skel);

}



static void test_stacktrace_ips_raw_tp(void)

{

	__u32 info_len = sizeof(struct bpf_prog_info);

	LIBBPF_OPTS(bpf_test_run_opts, topts);

	struct bpf_prog_info info = {};

	struct stacktrace_ips *skel;

	__u64 bpf_prog_ksym = 0;

	int err;



	skel = stacktrace_ips__open_and_load();

	if (!ASSERT_OK_PTR(skel, "stacktrace_ips__open_and_load"))

		return;



	if (!skel->kconfig->CONFIG_UNWINDER_ORC) {

		test__skip();

		goto cleanup;

	}



	skel->links.rawtp_test = bpf_program__attach_raw_tracepoint(

							skel->progs.rawtp_test,

							"bpf_testmod_test_read");

	if (!ASSERT_OK_PTR(skel->links.rawtp_test, "bpf_program__attach_raw_tracepoint"))

		goto cleanup;



	/* get bpf program address */

	info.jited_ksyms = ptr_to_u64(&bpf_prog_ksym);

	info.nr_jited_ksyms = 1;

	err = bpf_prog_get_info_by_fd(bpf_program__fd(skel->progs.rawtp_test),

				      &info, &info_len);

	if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd"))

		goto cleanup;



	trigger_module_test_read(1);



	load_kallsyms();



	check_stacktrace_ips(bpf_map__fd(skel->maps.stackmap), skel->bss->stack_key, 2,

			     bpf_prog_ksym,

			     ksym_get_addr("bpf_trace_run2"));



cleanup:

	stacktrace_ips__destroy(skel);

}



static void __test_stacktrace_ips(void)

{

	if (test__start_subtest("kprobe_multi"))

		test_stacktrace_ips_kprobe_multi(false);

	if (test__start_subtest("kretprobe_multi"))

		test_stacktrace_ips_kprobe_multi(true);

	if (test__start_subtest("raw_tp"))

		test_stacktrace_ips_raw_tp();

}

#else

static void __test_stacktrace_ips(void)

{

	test__skip();

}

#endif



void test_stacktrace_ips(void)

{

	__test_stacktrace_ips();

}