[PATCH v5 0/3] Fix the incorrect register read for syscalls on x86_64

From: Kenta Tada <Kenta.Tada@sony.com>
To: andrii@kernel.org, bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, kafai@fb.com,
	songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com,
	kpsingh@kernel.org, Kenta Tada <Kenta.Tada@sony.com>
Subject: [PATCH v5 0/3] Fix the incorrect register read for syscalls on x86_64
Date: Mon, 24 Jan 2022 23:16:19 +0900	[thread overview]
Message-ID: <20220124141622.4378-1-Kenta.Tada@sony.com> (raw)

Currently, rcx is read as the fourth parameter of syscall on x86_64.
But x86_64 Linux System Call convention uses r10 actually.
This commit adds the wrapper for users who want to access to
syscall params to analyze the user space.

Changelog:
----------
v1 -> v2:
- Rebase to current bpf-next
https://lore.kernel.org/bpf/20211222213924.1869758-1-andrii@kernel.org/

v2 -> v3:
- Modify the definition of SYSCALL macros for only targeted archs.
- Define __BPF_TARGET_MISSING variants for completeness.
- Remove CORE variants. These macros will not be used.
- Add a selftest.

v3 -> v4:
- Modify a selftest not to use serial tests.
- Modify a selftest to use ASSERT_EQ().
- Extract syscall wrapper for all the other tests.
- Add CORE variants.

v4 -> v5:
- Modify the CORE variant macro not to read memory directly.
- Remove the unnecessary comment.
- Add a selftest for the CORE variant.

Kenta Tada (3):
  libbpf: Extract syscall wrapper
  libbpf: Fix the incorrect register read for syscalls on x86_64
  libbpf: Add a test to confirm PT_REGS_PARM4_SYSCALL

 tools/lib/bpf/bpf_tracing.h                   | 34 ++++++++++
 .../bpf/prog_tests/test_bpf_syscall_macro.c   | 63 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/bpf_misc.h  | 19 ++++++
 .../selftests/bpf/progs/bpf_syscall_macro.c   | 64 +++++++++++++++++++
 .../selftests/bpf/progs/test_probe_user.c     | 15 +----
 5 files changed, 181 insertions(+), 14 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_misc.h
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_syscall_macro.c

-- 
2.32.0