From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 207E2285C95; Tue, 16 Sep 2025 21:53:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059601; cv=none; b=aosdW4HGI7vgU+vXZGDZ2/JysRi0dBrJGY0mMRiD53e5047Cay5a7TWsAORN+DmlaHf3iwq1vX2AkhNURM9jUvrD3VSb93YENheplr7+ofjoltNB90vtyBkzICPp3L56YNCBetzE2imuQjhUfIqcNaBDUKICVTMsBwMOgUWSyug= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059601; c=relaxed/simple; bh=vamR6nnchvOX6ID/s4Gnk1+hiU0FEri8mSpRjt7jFtw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=agEKUykpEyGuOTAfvg1Vx5wCg9WK3Cz6WXiUiFsHCqaPw2t+pUbdpFg+Wn9u+80wdsAKtr+0dUMMVH4RspzivHeBxQxrCLLAR96oza7a7i+MUk3JeJrMzn6C/OnPg5Uswx9s91Df5u+juEB16prBBtzTs2Bq6lJkeF2TosASH6A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M7jU4Uex; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M7jU4Uex" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DBCBEC4CEEB; Tue, 16 Sep 2025 21:53:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758059600; bh=vamR6nnchvOX6ID/s4Gnk1+hiU0FEri8mSpRjt7jFtw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M7jU4UexoKNz9UCdo6Z+OPlNiiSZJ69JJL5tumqug7YZGxF8MR++abAn3htBLUDoR 4Gg/BjAUIrN0+sBcLhma3OMWgay6Xqkh5AECoIoyL75vELiFVSuG5PAOXouc6g6pW9 gYFzsjX7SXLJtVbBUeQvLzFVG/tVNU8KpB8FyM1qCQJZfKu+5X9vQocy50zcd7oycP auwqfnJ83a8YB65XzUu8DsrFfQnO0rv/F0sXX1UFfS8DYet/CXsLWWIOze9yrC9ouQ j7u/ql2wFQP4Yx/C61viPbiW2UOSBjdgbSmoU5LsECjRN81miowKgE126FqbiMOi8e YWU4O8ObXk76A== From: Jiri Olsa To: Oleg Nesterov , Masami Hiramatsu , Peter Zijlstra , Andrii Nakryiko Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Ingo Molnar Subject: [PATCHv4 bpf-next 1/6] bpf: Allow uprobe program to change context registers Date: Tue, 16 Sep 2025 23:52:56 +0200 Message-ID: <20250916215301.664963-2-jolsa@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250916215301.664963-1-jolsa@kernel.org> References: <20250916215301.664963-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently uprobe (BPF_PROG_TYPE_KPROBE) program can't write to the context registers data. While this makes sense for kprobe attachments, for uprobe attachment it might make sense to be able to change user space registers to alter application execution. Since uprobe and kprobe programs share the same type (BPF_PROG_TYPE_KPROBE), we can't deny write access to context during the program load. We need to check on it during program attachment to see if it's going to be kprobe or uprobe. Storing the program's write attempt to context and checking on it during the attachment. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- include/linux/bpf.h | 1 + kernel/events/core.c | 4 ++++ kernel/trace/bpf_trace.c | 9 +++++++-- 3 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 41f776071ff5..8dfaf5e9f7fb 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1624,6 +1624,7 @@ struct bpf_prog_aux { bool priv_stack_requested; bool changes_pkt_data; bool might_sleep; + bool kprobe_write_ctx; u64 prog_array_member_cnt; /* counts how many times as member of prog_arr= ay */ struct mutex ext_mutex; /* mutex for is_extended and prog_array_member_cn= t */ struct bpf_arena *arena; diff --git a/kernel/events/core.c b/kernel/events/core.c index 820127536e62..1d354778dcd4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11232,6 +11232,10 @@ static int __perf_event_set_bpf_prog(struct perf_e= vent *event, if (prog->kprobe_override && !is_kprobe) return -EINVAL; =20 + /* Writing to context allowed only for uprobes. */ + if (prog->aux->kprobe_write_ctx && !is_uprobe) + return -EINVAL; + if (is_tracepoint || is_syscall_tp) { int off =3D trace_event_get_offsets(event->tp_event); =20 diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 606007c387c5..b0deaeebb34a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1521,8 +1521,6 @@ static bool kprobe_prog_is_valid_access(int off, int = size, enum bpf_access_type { if (off < 0 || off >=3D sizeof(struct pt_regs)) return false; - if (type !=3D BPF_READ) - return false; if (off % size !=3D 0) return false; /* @@ -1532,6 +1530,9 @@ static bool kprobe_prog_is_valid_access(int off, int = size, enum bpf_access_type if (off + size > sizeof(struct pt_regs)) return false; =20 + if (type =3D=3D BPF_WRITE) + prog->aux->kprobe_write_ctx =3D true; + return true; } =20 @@ -2918,6 +2919,10 @@ int bpf_kprobe_multi_link_attach(const union bpf_att= r *attr, struct bpf_prog *pr if (!is_kprobe_multi(prog)) return -EINVAL; =20 + /* Writing to context is not allowed for kprobes. */ + if (prog->aux->kprobe_write_ctx) + return -EINVAL; + flags =3D attr->link_create.kprobe_multi.flags; if (flags & ~BPF_F_KPROBE_MULTI_RETURN) return -EINVAL; --=20 2.51.0 From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 47308287515; Tue, 16 Sep 2025 21:53:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059613; cv=none; b=OhpLVahuZnQ9enlvDP3NoKQvxjy/dYasuL15EcGIPj6+TOvxwnsnIMFfu3GjS2B60XQYKMelcmIiBRMlpiIKH5X2rvjKw7IulecEr60tm4WmFBaDnPrJvEFQ1wvrMm+YC+hvB3aT0AjvaYNhKYxC+DzcqA46yPgGO39+k9V+EXE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059613; c=relaxed/simple; bh=8EBfcHDmTJFDZsBygObtTJtulBbopVoDqDbqo+5ESa0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; 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charset="utf-8" If uprobe handler changes instruction pointer we still execute single step) or emulate the original instruction and increment the (new) ip with its length. This makes the new instruction pointer bogus and application will likely crash on illegal instruction execution. If user decided to take execution elsewhere, it makes little sense to execute the original instruction, so let's skip it. Acked-by: Oleg Nesterov Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- kernel/events/uprobes.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 7ca1940607bd..2b32c32bcb77 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -2741,6 +2741,13 @@ static void handle_swbp(struct pt_regs *regs) =20 handler_chain(uprobe, regs); =20 + /* + * If user decided to take execution elsewhere, it makes little sense + * to execute the original instruction, so let's skip it. + */ + if (instruction_pointer(regs) !=3D bp_vaddr) + goto out; + if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) goto out; =20 --=20 2.51.0 From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 69982287515; Tue, 16 Sep 2025 21:53:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059626; cv=none; b=Jtj7kNoU7tvTEUnzrXHeuWBmqTCLaGo8zyev7xyXIw9ynm1vCK47+LeQf5k7N6KS2UeWXoOcKvw9uS9Yuie5N7B75u2sgTW3GJWVL7vt++LlhGDLGwcnLN2Co4fc7rW6fRfvsQiDZ63GsEM9LpvbE4dszgtjG8kAg/7GUoP/U2Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059626; c=relaxed/simple; bh=ci4HGlaaG9ACPOcomhTpHvhq0lKQg8q1VIgALdYzygE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XgXpmpJNJSWWXpD/KGCBqd4ZijxptGPP/fBk07TYhEHc2Pe+Tr7S1c3PrbSqm5eT1flv6Nci4DcyHLs0A8Lw0jkxv3zwRoakx8kgbWoZTHCjvLetynaXvA02/dn+HHnoqKDDoapV3oAUVVDqKNoRWY86EgvdZ62KOLsP3r/8vI8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lmG18EwW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lmG18EwW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2440DC4CEEB; Tue, 16 Sep 2025 21:53:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758059626; bh=ci4HGlaaG9ACPOcomhTpHvhq0lKQg8q1VIgALdYzygE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lmG18EwWUR0qmnPpvJiBUdmcZzO+Lmqm6BFo/Xws9l+F7KK6z/a0DulOlXNZzxrNg S5RYKJ1elUbtOAJrK+JeowgCuyYJATgXoERhs1ClOJSlxz0/QqbmxA5w3LP5hqqdZM +NM+8roUeCIdeylOWshGwmlUGX+aP/tFIkLoWmBxRMxChnpYCwapUdIQ4CcRnIVbbG SXHBGJfMqfNOqvSp8ejbPH0K/KqH5/YDx0njLCFaYQoEIgO/A+B0VLLvEoDkRCJA43 RPGFu3n53lS6bkffAWK3ALU8Otx81cmzb+hMC7webtDKcteywH9TuQjSdUV8J1ABJg 2gFHGce/mitNg== From: Jiri Olsa To: Oleg Nesterov , Masami Hiramatsu , Peter Zijlstra , Andrii Nakryiko Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Ingo Molnar Subject: [PATCHv4 bpf-next 3/6] selftests/bpf: Add uprobe context registers changes test Date: Tue, 16 Sep 2025 23:52:58 +0200 Message-ID: <20250916215301.664963-4-jolsa@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250916215301.664963-1-jolsa@kernel.org> References: <20250916215301.664963-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Adding test to check we can change common register values through uprobe program. It's x86_64 specific test. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- .../testing/selftests/bpf/prog_tests/uprobe.c | 114 +++++++++++++++++- .../testing/selftests/bpf/progs/test_uprobe.c | 24 ++++ 2 files changed, 137 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe.c b/tools/testin= g/selftests/bpf/prog_tests/uprobe.c index cf3e0e7a64fa..19dd900df188 100644 --- a/tools/testing/selftests/bpf/prog_tests/uprobe.c +++ b/tools/testing/selftests/bpf/prog_tests/uprobe.c @@ -2,6 +2,7 @@ /* Copyright (c) 2023 Hengqi Chen */ =20 #include +#include #include "test_uprobe.skel.h" =20 static FILE *urand_spawn(int *pid) @@ -33,7 +34,7 @@ static int urand_trigger(FILE **urand_pipe) return exit_code; } =20 -void test_uprobe(void) +static void test_uprobe_attach(void) { LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts); struct test_uprobe *skel; @@ -93,3 +94,114 @@ void test_uprobe(void) pclose(urand_pipe); test_uprobe__destroy(skel); } + +#ifdef __x86_64__ +__naked __maybe_unused unsigned long uprobe_regs_change_trigger(void) +{ + asm volatile ( + "ret\n" + ); +} + +static __naked void uprobe_regs_change(struct pt_regs *before, struct pt_r= egs *after) +{ + asm volatile ( + "movq %r11, 48(%rdi)\n" + "movq %r10, 56(%rdi)\n" + "movq %r9, 64(%rdi)\n" + "movq %r8, 72(%rdi)\n" + "movq %rax, 80(%rdi)\n" + "movq %rcx, 88(%rdi)\n" + "movq %rdx, 96(%rdi)\n" + "movq %rsi, 104(%rdi)\n" + "movq %rdi, 112(%rdi)\n" + + /* save 2nd argument */ + "pushq %rsi\n" + "call uprobe_regs_change_trigger\n" + + /* save return value and load 2nd argument pointer to rax */ + "pushq %rax\n" + "movq 8(%rsp), %rax\n" + + "movq %r11, 48(%rax)\n" + "movq %r10, 56(%rax)\n" + "movq %r9, 64(%rax)\n" + "movq %r8, 72(%rax)\n" + "movq %rcx, 88(%rax)\n" + "movq %rdx, 96(%rax)\n" + "movq %rsi, 104(%rax)\n" + "movq %rdi, 112(%rax)\n" + + /* restore return value and 2nd argument */ + "pop %rax\n" + "pop %rsi\n" + + "movq %rax, 80(%rsi)\n" + "ret\n" + ); +} + +static void regs_common(void) +{ + struct pt_regs before =3D {}, after =3D {}, expected =3D { + .rax =3D 0xc0ffe, + .rcx =3D 0xbad, + .rdx =3D 0xdead, + .r8 =3D 0x8, + .r9 =3D 0x9, + .r10 =3D 0x10, + .r11 =3D 0x11, + .rdi =3D 0x12, + .rsi =3D 0x13, + }; + LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts); + struct test_uprobe *skel; + + skel =3D test_uprobe__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + skel->bss->my_pid =3D getpid(); + skel->bss->regs =3D expected; + + uprobe_opts.func_name =3D "uprobe_regs_change_trigger"; + skel->links.test_regs_change =3D bpf_program__attach_uprobe_opts(skel->pr= ogs.test_regs_change, + -1, + "/proc/self/exe", + 0 /* offset */, + &uprobe_opts); + if (!ASSERT_OK_PTR(skel->links.test_regs_change, "bpf_program__attach_upr= obe_opts")) + goto cleanup; + + uprobe_regs_change(&before, &after); + + ASSERT_EQ(after.rax, expected.rax, "ax"); + ASSERT_EQ(after.rcx, expected.rcx, "cx"); + ASSERT_EQ(after.rdx, expected.rdx, "dx"); + ASSERT_EQ(after.r8, expected.r8, "r8"); + ASSERT_EQ(after.r9, expected.r9, "r9"); + ASSERT_EQ(after.r10, expected.r10, "r10"); + ASSERT_EQ(after.r11, expected.r11, "r11"); + ASSERT_EQ(after.rdi, expected.rdi, "rdi"); + ASSERT_EQ(after.rsi, expected.rsi, "rsi"); + +cleanup: + test_uprobe__destroy(skel); +} + +static void test_uprobe_regs_change(void) +{ + if (test__start_subtest("regs_change_common")) + regs_common(); +} +#else +static void test_uprobe_regs_change(void) { } +#endif + +void test_uprobe(void) +{ + if (test__start_subtest("attach")) + test_uprobe_attach(); + test_uprobe_regs_change(); +} diff --git a/tools/testing/selftests/bpf/progs/test_uprobe.c b/tools/testin= g/selftests/bpf/progs/test_uprobe.c index 896c88a4960d..9437bd76a437 100644 --- a/tools/testing/selftests/bpf/progs/test_uprobe.c +++ b/tools/testing/selftests/bpf/progs/test_uprobe.c @@ -59,3 +59,27 @@ int BPF_UPROBE(test4) test4_result =3D 1; return 0; } + +#if defined(__TARGET_ARCH_x86) +struct pt_regs regs; + +SEC("uprobe") +int BPF_UPROBE(test_regs_change) +{ + pid_t pid =3D bpf_get_current_pid_tgid() >> 32; + + if (pid !=3D my_pid) + return 0; + + ctx->ax =3D regs.ax; + ctx->cx =3D regs.cx; + ctx->dx =3D regs.dx; + ctx->r8 =3D regs.r8; + ctx->r9 =3D regs.r9; + ctx->r10 =3D regs.r10; + ctx->r11 =3D regs.r11; + ctx->di =3D regs.di; + ctx->si =3D regs.si; + return 0; +} +#endif --=20 2.51.0 From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2297F285C95; Tue, 16 Sep 2025 21:53:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059639; cv=none; b=tA2wyxndbSN84eHxzm/qQwu9owzoNIEDvvXlhxpFqRdb3JUXh7ksz6EjGLk3XCKpKcYGuMFvyyhMMNCS9cmtZWAKKO8loaxU5l24i+1OvoI116TUuN+HiZVDPy2tSlGkvsQt0wO7TPiXONM0iDmXgHbKeL/WDjnOcgli0Cyo0go= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059639; c=relaxed/simple; bh=yZmUc8dAaJ6kpzj+rfiloC/S5Y3mRiKr3Ww/w18JtC8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; 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charset="utf-8" Adding test to check we can change the application execution through instruction pointer change through uprobe program. It's x86_64 specific test. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- .../testing/selftests/bpf/prog_tests/uprobe.c | 42 +++++++++++++++++++ .../testing/selftests/bpf/progs/test_uprobe.c | 14 +++++++ 2 files changed, 56 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe.c b/tools/testin= g/selftests/bpf/prog_tests/uprobe.c index 19dd900df188..86404476c1da 100644 --- a/tools/testing/selftests/bpf/prog_tests/uprobe.c +++ b/tools/testing/selftests/bpf/prog_tests/uprobe.c @@ -190,10 +190,52 @@ static void regs_common(void) test_uprobe__destroy(skel); } =20 +static noinline unsigned long uprobe_regs_change_ip_1(void) +{ + return 0xc0ffee; +} + +static noinline unsigned long uprobe_regs_change_ip_2(void) +{ + return 0xdeadbeef; +} + +static void regs_ip(void) +{ + LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts); + struct test_uprobe *skel; + unsigned long ret; + + skel =3D test_uprobe__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + skel->bss->my_pid =3D getpid(); + skel->bss->ip =3D (unsigned long) uprobe_regs_change_ip_2; + + uprobe_opts.func_name =3D "uprobe_regs_change_ip_1"; + skel->links.test_regs_change_ip =3D bpf_program__attach_uprobe_opts( + skel->progs.test_regs_change_ip, + -1, + "/proc/self/exe", + 0 /* offset */, + &uprobe_opts); + if (!ASSERT_OK_PTR(skel->links.test_regs_change_ip, "bpf_program__attach_= uprobe_opts")) + goto cleanup; + + ret =3D uprobe_regs_change_ip_1(); + ASSERT_EQ(ret, 0xdeadbeef, "ret"); + +cleanup: + test_uprobe__destroy(skel); +} + static void test_uprobe_regs_change(void) { if (test__start_subtest("regs_change_common")) regs_common(); + if (test__start_subtest("regs_change_ip")) + regs_ip(); } #else static void test_uprobe_regs_change(void) { } diff --git a/tools/testing/selftests/bpf/progs/test_uprobe.c b/tools/testin= g/selftests/bpf/progs/test_uprobe.c index 9437bd76a437..12f4065fca20 100644 --- a/tools/testing/selftests/bpf/progs/test_uprobe.c +++ b/tools/testing/selftests/bpf/progs/test_uprobe.c @@ -82,4 +82,18 @@ int BPF_UPROBE(test_regs_change) ctx->si =3D regs.si; return 0; } + +unsigned long ip; + +SEC("uprobe") +int BPF_UPROBE(test_regs_change_ip) +{ + pid_t pid =3D bpf_get_current_pid_tgid() >> 32; + + if (pid !=3D my_pid) + return 0; + + ctx->ip =3D ip; + return 0; +} #endif --=20 2.51.0 From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EB38831FECA; Tue, 16 Sep 2025 21:54:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758059653; cv=none; b=kQjTtHvRN2W6T1y5nCl3y6ICXU068BzdIoeTtFsOtlQ0S5IVV4TgHqfcJ9DI80QZccZsC+TCuey8+O+ocyD93PzZjWn8+T6TX4yLHkgaSlNKd+56ugrQTQjnkYjUpfDb5QHR02eVD1o0PiExkmzk5iIeEIktoSipaJZXPqxJZHk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; 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charset="utf-8" Adding test to check we can't attach standard kprobe program that writes to the context. It's x86_64 specific test. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- .../selftests/bpf/prog_tests/attach_probe.c | 28 +++++++++++++++++++ .../selftests/bpf/progs/kprobe_write_ctx.c | 15 ++++++++++ 2 files changed, 43 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/kprobe_write_ctx.c diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/= testing/selftests/bpf/prog_tests/attach_probe.c index cabc51c2ca6b..9e77e5da7097 100644 --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c @@ -3,6 +3,7 @@ #include "test_attach_kprobe_sleepable.skel.h" #include "test_attach_probe_manual.skel.h" #include "test_attach_probe.skel.h" +#include "kprobe_write_ctx.skel.h" =20 /* this is how USDT semaphore is actually defined, except volatile modifie= r */ volatile unsigned short uprobe_ref_ctr __attribute__((unused)) __attribute= ((section(".probes"))); @@ -201,6 +202,31 @@ static void test_attach_kprobe_long_event_name(void) test_attach_probe_manual__destroy(skel); } =20 +#ifdef __x86_64__ +/* attach kprobe/kretprobe long event name testings */ +static void test_attach_kprobe_write_ctx(void) +{ + struct kprobe_write_ctx *skel =3D NULL; + struct bpf_link *link =3D NULL; + + skel =3D kprobe_write_ctx__open_and_load(); + if (!ASSERT_OK_PTR(skel, "kprobe_write_ctx__open_and_load")) + return; + + link =3D bpf_program__attach_kprobe_opts(skel->progs.kprobe_write_ctx, + "bpf_fentry_test1", NULL); + if (!ASSERT_ERR_PTR(link, "bpf_program__attach_kprobe_opts")) + bpf_link__destroy(link); + + kprobe_write_ctx__destroy(skel); +} +#else +static void test_attach_kprobe_write_ctx(void) +{ + test__skip(); +} +#endif + static void test_attach_probe_auto(struct test_attach_probe *skel) { struct bpf_link *uprobe_err_link; @@ -406,6 +432,8 @@ void test_attach_probe(void) test_attach_uprobe_long_event_name(); if (test__start_subtest("kprobe-long_name")) test_attach_kprobe_long_event_name(); + if (test__start_subtest("kprobe-write-ctx")) + test_attach_kprobe_write_ctx(); =20 cleanup: test_attach_probe__destroy(skel); diff --git a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c b/tools/t= esting/selftests/bpf/progs/kprobe_write_ctx.c new file mode 100644 index 000000000000..4621a5bef4e2 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "vmlinux.h" +#include +#include + +char _license[] SEC("license") =3D "GPL"; + +#if defined(__TARGET_ARCH_x86) +SEC("kprobe") +int kprobe_write_ctx(struct pt_regs *ctx) +{ + ctx->ax =3D 0; + return 0; +} +#endif --=20 2.51.0 From nobody Thu Oct 2 22:48:45 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 022BB31FEE4; Tue, 16 Sep 2025 21:54:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; 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Tue, 16 Sep 2025 21:54:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758059664; bh=OsEEWV4wNkbsvLkZHIBDGiDZBWoY4hQzlY0ncyYsXjw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iwBZCfP9Ol3xjNu04Rpzhae7+ENY9bGrvTObrEij5MSNmeTI8QPz3y/DkglGNUUu5 BF9ziHp/vTpqq7PkLgh1XQej2UzJkcPiwZ7PfBOlD7Q806ETF+3DyidATmnfPLPhrR DWPcnutLhcYj8idhWF9F5B2o+QhLB8Y3kizSiwzRYNTC5s2k6nurAvIDYzW9TFMwb2 fV0U5eLCgsp/WSdVfqQsKBVvjH3BIUBOnWXLFXq5DNfprGlpyx6KQGvkNN2yLdQz1r FRaekHmI6ARNupz7C2RzW/KluTjcs9C4z3FsfDl5nkm+P+FbvBXeu6HU58IBkcxLhT DzRD0WQd25EYA== From: Jiri Olsa To: Oleg Nesterov , Masami Hiramatsu , Peter Zijlstra , Andrii Nakryiko Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Ingo Molnar Subject: [PATCHv4 bpf-next 6/6] selftests/bpf: Add kprobe multi write ctx attach test Date: Tue, 16 Sep 2025 23:53:01 +0200 Message-ID: <20250916215301.664963-7-jolsa@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250916215301.664963-1-jolsa@kernel.org> References: <20250916215301.664963-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Adding test to check we can't attach kprobe multi program that writes to the context. It's x86_64 specific test. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- .../bpf/prog_tests/kprobe_multi_test.c | 27 +++++++++++++++++++ .../selftests/bpf/progs/kprobe_write_ctx.c | 7 +++++ 2 files changed, 34 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/t= ools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c index 171706e78da8..6cfaa978bc9a 100644 --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c @@ -7,6 +7,7 @@ #include "kprobe_multi_session.skel.h" #include "kprobe_multi_session_cookie.skel.h" #include "kprobe_multi_verifier.skel.h" +#include "kprobe_write_ctx.skel.h" #include "bpf/libbpf_internal.h" #include "bpf/hashmap.h" =20 @@ -539,6 +540,30 @@ static void test_attach_override(void) kprobe_multi_override__destroy(skel); } =20 +#ifdef __x86_64__ +static void test_attach_write_ctx(void) +{ + struct kprobe_write_ctx *skel =3D NULL; + struct bpf_link *link =3D NULL; + + skel =3D kprobe_write_ctx__open_and_load(); + if (!ASSERT_OK_PTR(skel, "kprobe_write_ctx__open_and_load")) + return; + + link =3D bpf_program__attach_kprobe_opts(skel->progs.kprobe_multi_write_c= tx, + "bpf_fentry_test1", NULL); + if (!ASSERT_ERR_PTR(link, "bpf_program__attach_kprobe_opts")) + bpf_link__destroy(link); + + kprobe_write_ctx__destroy(skel); +} +#else +static void test_attach_write_ctx(void) +{ + test__skip(); +} +#endif + void serial_test_kprobe_multi_bench_attach(void) { if (test__start_subtest("kernel")) @@ -578,5 +603,7 @@ void test_kprobe_multi_test(void) test_session_cookie_skel_api(); if (test__start_subtest("unique_match")) test_unique_match(); + if (test__start_subtest("attach_write_ctx")) + test_attach_write_ctx(); RUN_TESTS(kprobe_multi_verifier); } diff --git a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c b/tools/t= esting/selftests/bpf/progs/kprobe_write_ctx.c index 4621a5bef4e2..f77aef0474d3 100644 --- a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c +++ b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c @@ -12,4 +12,11 @@ int kprobe_write_ctx(struct pt_regs *ctx) ctx->ax =3D 0; return 0; } + +SEC("kprobe.multi") +int kprobe_multi_write_ctx(struct pt_regs *ctx) +{ + ctx->ax =3D 0; + return 0; +} #endif --=20 2.51.0