Do not use memcpy() to extract syscall arguments from struct pt_regs but rather just perform direct assignments. The performance benchmarks with Generic Entry patch[1] with audit on from perf bench basic syscall on kunpeng920 gives roughly a 1% performance uplift and also aligns the implementation with x86 and RISC-V. | Metric | W/O this patch | With this patch | Change | | ---------- | -------------- | --------------- | --------- | | Total time | 2.241 [sec] | 2.211 [sec] | ↓1.36% | | usecs/op | 0.224157 | 0.221146 | ↓1.36% | | ops/sec | 4,461,157 | 4,501,409 | ↑0.9% | Before: <syscall_get_arguments.constprop.0>: aa0103e2 mov x2, x1 91002003 add x3, x0, #0x8 f9408804 ldr x4, [x0, #272] f8008444 str x4, [x2], #8 a9409404 ldp x4, x5, [x0, #8] a9009424 stp x4, x5, [x1, #8] a9418400 ldp x0, x1, [x0, #24] a9010440 stp x0, x1, [x2, #16] f9401060 ldr x0, [x3, #32] f9001040 str x0, [x2, #32] d65f03c0 ret d503201f nop After: a9408e82 ldp x2, x3, [x20, #8] 2a1603e0 mov w0, w22 f9400e84 ldr x4, [x20, #24] f9408a81 ldr x1, [x20, #272] 9401c4ba bl ffff800080215ca8 <__audit_syscall_entry> [1]: https://lore.kernel.org/all/20251126071446.3234218-1-ruanjinjie@huawei.com/ Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/include/asm/syscall.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index f3853047c28e..f3564ba97f7e 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -82,9 +82,11 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned long *args) { args[0] = regs->orig_x0; - args++; - - memcpy(args, ®s->regs[1], 5 * sizeof(args[0])); + args[1] = regs->regs[1]; + args[2] = regs->regs[2]; + args[3] = regs->regs[3]; + args[4] = regs->regs[4]; + args[5] = regs->regs[5]; } static inline void syscall_set_arguments(struct task_struct *task, -- 2.34.1