[PATCH bpf-next 1/2] libbpf: Fix accessing first syscall argument on RV64
From: Pu Lehui <hidden>
Date: 2024-08-29 13:30:18
Also in:
bpf, linux-riscv
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Pu Lehui <pulehui@huawei.com> On RV64, as Ilya mentioned before [0], the first syscall parameter should be accessed through orig_a0 (see arch/riscv64/include/asm/syscall.h), otherwise it will cause selftests like bpf_syscall_macro, vmlinux, test_lsm, etc. to fail on RV64. Let's fix it by using the struct pt_regs style to provide access to it only through PT_REGS_PARM1_CORE_SYSCALL(). Link: https://lore.kernel.org/bpf/20220209021745.2215452-1-iii@linux.ibm.com (local) [0] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- tools/lib/bpf/bpf_tracing.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index 9314fa95f04e..388f30cf7914 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h@@ -351,6 +351,10 @@ struct pt_regs___arm64 { * https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc#risc-v-calling-conventions */ +struct pt_regs___riscv { + unsigned long orig_a0; +}; + /* riscv provides struct user_regs_struct instead of struct pt_regs to userspace */ #define __PT_REGS_CAST(x) ((const struct user_regs_struct *)(x)) #define __PT_PARM1_REG a0
@@ -362,12 +366,15 @@ struct pt_regs___arm64 { #define __PT_PARM7_REG a6 #define __PT_PARM8_REG a7 -#define __PT_PARM1_SYSCALL_REG __PT_PARM1_REG +#define __PT_PARM1_SYSCALL_REG orig_a0 #define __PT_PARM2_SYSCALL_REG __PT_PARM2_REG #define __PT_PARM3_SYSCALL_REG __PT_PARM3_REG #define __PT_PARM4_SYSCALL_REG __PT_PARM4_REG #define __PT_PARM5_SYSCALL_REG __PT_PARM5_REG #define __PT_PARM6_SYSCALL_REG __PT_PARM6_REG +#define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1_CORE_SYSCALL(x) +#define PT_REGS_PARM1_CORE_SYSCALL(x) \ + BPF_CORE_READ((const struct pt_regs___riscv *)(x), __PT_PARM1_SYSCALL_REG) #define __PT_RET_REG ra #define __PT_FP_REG s0
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2.34.1