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| author | kib <kib@FreeBSD.org> | 2011-09-11 16:08:10 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2011-09-11 16:08:10 +0000 |
| commit | 44839b3d920a0ed96b2ab9cb9de46f7d518ee8aa (patch) | |
| tree | 99c6f111999a382d1f7d69965310b2e85bc02d36 /sys/amd64/amd64/exception.S | |
| parent | 55d0a85118b14ca04ad09a2e920c8fac09fb6053 (diff) | |
| download | FreeBSD-src-44839b3d920a0ed96b2ab9cb9de46f7d518ee8aa.zip FreeBSD-src-44839b3d920a0ed96b2ab9cb9de46f7d518ee8aa.tar.gz | |
Perform amd64-specific microoptimizations for native syscall entry
sequence. The effect is ~1% on the microbenchmark.
In particular, do not restore registers which are preserved by the
C calling sequence. Align the jump target. Avoid unneeded memory
accesses by calculating some data in syscall entry trampoline.
Reviewed by: jhb
Approved by: re (bz)
MFC after: 2 weeks
Diffstat (limited to 'sys/amd64/amd64/exception.S')
| -rw-r--r-- | sys/amd64/amd64/exception.S | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S index c537a4f..b5b84ed 100644 --- a/sys/amd64/amd64/exception.S +++ b/sys/amd64/amd64/exception.S @@ -380,8 +380,11 @@ IDTVEC(fast_syscall) movl $TF_HASSEGS,TF_FLAGS(%rsp) cld FAKE_MCOUNT(TF_RIP(%rsp)) - movq %rsp,%rdi - call syscall + movq PCPU(CURTHREAD),%rdi + movq %rsp,TD_FRAME(%rdi) + movl TF_RFLAGS(%rsp),%esi + andl $PSL_T,%esi + call amd64_syscall 1: movq PCPU(CURPCB),%rax /* Disable interrupts before testing PCB_FULL_IRET. */ cli @@ -396,17 +399,12 @@ IDTVEC(fast_syscall) call ast jmp 1b 2: /* Restore preserved registers. */ + .align 16 MEXITCOUNT movq TF_RDI(%rsp),%rdi /* bonus; preserve arg 1 */ movq TF_RSI(%rsp),%rsi /* bonus: preserve arg 2 */ movq TF_RDX(%rsp),%rdx /* return value 2 */ movq TF_RAX(%rsp),%rax /* return value 1 */ - movq TF_RBX(%rsp),%rbx /* C preserved */ - movq TF_RBP(%rsp),%rbp /* C preserved */ - movq TF_R12(%rsp),%r12 /* C preserved */ - movq TF_R13(%rsp),%r13 /* C preserved */ - movq TF_R14(%rsp),%r14 /* C preserved */ - movq TF_R15(%rsp),%r15 /* C preserved */ movq TF_RFLAGS(%rsp),%r11 /* original %rflags */ movq TF_RIP(%rsp),%rcx /* original %rip */ movq TF_RSP(%rsp),%r9 /* user stack pointer */ |
