On 2024/9/5 4:21, Andrii Nakryiko wrote:
On Fri, Aug 30, 2024 at 9:17 PM Pu Lehui <pulehui@xxxxxxxxxxxxxxx> wrote:From: Pu Lehui <pulehui@xxxxxxxxxx> Currently PT_REGS_PARM1 SYSCALL(x) is consistent with PT_REGS_PARM1_CORE SYSCALL(x), which will introduce the overhead of BPF_CORE_READ(), taking into account the read pt_regs comes directly from the context, let's use CO-RE direct read to access the first system call argument. Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx> --- tools/lib/bpf/bpf_tracing.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h index e7d9382efeb3..051c408e6aed 100644 --- a/tools/lib/bpf/bpf_tracing.h +++ b/tools/lib/bpf/bpf_tracing.h @@ -222,7 +222,7 @@ struct pt_regs___s390 { struct pt_regs___arm64 { unsigned long orig_x0; -}; +} __attribute__((preserve_access_index)); /* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */ #define __PT_REGS_CAST(x) ((const struct user_pt_regs *)(x)) @@ -241,7 +241,7 @@ struct pt_regs___arm64 { #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_SYSCALL(x) (((const struct pt_regs___arm64 *)(x))->orig_x0)It would probably be best (for consistency) to stick to using __PTR_PARM1_SYSCALL_REG instead of hard-coding orig_x0 here, no? I'll fix it up while applying. Same for patch #1 and #4. It would be great if you can double-check that final patches in bpf-next/master compile and work well for arm64, s390x, and RV64 (as I can't really test that much locally).
I check that locally with cross-platform vmtest on RV64, it looks good: Summary: 569/3944 PASSED, 104 SKIPPED, 0 FAILED and BPF CI meet happy on arm64, s390x.
#define PT_REGS_PARM1_CORE_SYSCALL(x) \ BPF_CORE_READ((const struct pt_regs___arm64 *)(x), __PT_PARM1_SYSCALL_REG) -- 2.34.1
