This patch set fixes and extends libbpf's bpf_tracing.h support for tracing
arguments of kprobes/uprobes, and syscall as a special case.
Depending on the architecture, anywhere between 3 and 8 arguments can be
passed to a function in registers (so relevant to kprobes and uprobes), but
before this patch set libbpf's macros in bpf_tracing.h only supported up to
5 arguments, which is limiting in practice. This patch set extends
bpf_tracing.h to support up to 8 arguments, if architecture allows. This
includes explicit PT_REGS_PARMx() macro family, as well as BPF_KPROBE() macro.
Now, with tracing syscall arguments situation is sometimes quite different.
For a lot of architectures syscall argument passing through registers differs
from function call sequence at least a little. For i386 it differs *a lot*.
This patch set addresses this issue across all currently supported
architectures and hopefully fixes existing issues. syscall(2) manpage defines
that either 6 or 7 arguments can be supported, depending on architecture, so
libbpf defines 6 or 7 registers per architecture to be used to fetch syscall
arguments.
Also, BPF_UPROBE and BPF_URETPROBE are introduced as part of this patch set.
They are aliases for BPF_KPROBE and BPF_KRETPROBE (as mechanics of argument
fetching of kernel functions and user-space functions are identical), but it
allows BPF users to have less confusing BPF-side code when working with
uprobes.
For both sets of changes selftests are extended to test these new register
definitions to architecture-defined limits. Unfortunately I don't have ability
to test it on all architectures, and BPF CI only tests 3 architecture (x86-64,
arm64, and s390x), so it would be greatly appreciated if people with access to
architectures other than above 3 helped review and test changes.
v1->v2:
- switched from mmap() to splice() syscall (Ilya);
- updated ABI spec link for s390x (Ilya);
- added a bunch of Tested-by and acks tags, thank you;
- dropped direct CCs because vger/patchworks blocked v1 patches, probably
due to too long CC list.
Andrii Nakryiko (25):
libbpf: add support for fetching up to 8 arguments in kprobes
libbpf: add 6th argument support for x86-64 in bpf_tracing.h
libbpf: fix arm and arm64 specs in bpf_tracing.h
libbpf: complete mips spec in bpf_tracing.h
libbpf: complete powerpc spec in bpf_tracing.h
libbpf: complete sparc spec in bpf_tracing.h
libbpf: complete riscv arch spec in bpf_tracing.h
libbpf: fix and complete ARC spec in bpf_tracing.h
libbpf: complete LoongArch (loongarch) spec in bpf_tracing.h
libbpf: add BPF_UPROBE and BPF_URETPROBE macro aliases
selftests/bpf: validate arch-specific argument registers limits
libbpf: improve syscall tracing support in bpf_tracing.h
libbpf: define x86-64 syscall regs spec in bpf_tracing.h
libbpf: define i386 syscall regs spec in bpf_tracing.h
libbpf: define s390x syscall regs spec in bpf_tracing.h
libbpf: define arm syscall regs spec in bpf_tracing.h
libbpf: define arm64 syscall regs spec in bpf_tracing.h
libbpf: define mips syscall regs spec in bpf_tracing.h
libbpf: define powerpc syscall regs spec in bpf_tracing.h
libbpf: define sparc syscall regs spec in bpf_tracing.h
libbpf: define riscv syscall regs spec in bpf_tracing.h
libbpf: define arc syscall regs spec in bpf_tracing.h
libbpf: define loongarch syscall regs spec in bpf_tracing.h
selftests/bpf: add 6-argument syscall tracing test
libbpf: clean up now not needed __PT_PARM{1-6}_SYSCALL_REG defaults
tools/lib/bpf/bpf_tracing.h | 303 +++++++++++++++---
.../bpf/prog_tests/test_bpf_syscall_macro.c | 17 +
.../bpf/prog_tests/uprobe_autoattach.c | 33 +-
tools/testing/selftests/bpf/progs/bpf_misc.h | 25 ++
.../selftests/bpf/progs/bpf_syscall_macro.c | 26 ++
.../bpf/progs/test_uprobe_autoattach.c | 48 ++-
6 files changed, 407 insertions(+), 45 deletions(-)
--
2.30.2
