mov insns are faster than push/pops: some CPUs can execute two movs per cycle, but only one push/pop.
Logic is not changed by this patch. Signed-off-by: Denys Vlasenko <[email protected]> CC: Linus Torvalds <[email protected]> CC: Oleg Nesterov <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: X86 ML <[email protected]> CC: Alexei Starovoitov <[email protected]> CC: Will Drewry <[email protected]> CC: Kees Cook <[email protected]> CC: [email protected] --- arch/x86/ia32/ia32entry.S | 54 ++++++++++++++++++++++------------------------- 1 file changed, 25 insertions(+), 29 deletions(-) diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index c70c9a0..844ef4f 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -119,28 +119,25 @@ ENTRY(ia32_sysenter_target) * disabled irqs, here we enable it straight after entry: */ ENABLE_INTERRUPTS(CLBR_NONE) - /* Construct iret frame (ss,rsp,rflags,cs,rip) */ + /* Construct part of iret frame (ss,rsp,rflags) */ movl %ebp,%ebp /* zero extension */ pushq_cfi $__USER32_DS /*CFI_REL_OFFSET ss,0*/ + movl %eax,%eax /* zero extension */ pushq_cfi %rbp CFI_REL_OFFSET rsp,0 pushfq_cfi /*CFI_REL_OFFSET rflags,0*/ - movl TI_sysenter_return+THREAD_INFO(%rsp,3*8),%r10d - CFI_REGISTER rip,r10 - pushq_cfi $__USER32_CS - /*CFI_REL_OFFSET cs,0*/ - movl %eax, %eax - /* Store thread_info->sysenter_return in rip stack slot */ - pushq_cfi %r10 - CFI_REL_OFFSET rip,0 - /* Store orig_ax */ - pushq_cfi %rax - /* Construct the rest of "struct pt_regs" */ cld - ALLOC_PTREGS_ON_STACK + /* Construct the rest of pt_regs */ + ALLOC_PTREGS_ON_STACK 3*8 /* 3*8: space for orig_ax,rip,cs */ + movl TI_sysenter_return+THREAD_INFO(%rsp,SIZEOF_PTREGS),%r10d SAVE_C_REGS_EXCEPT_R891011 + movq %rax,ORIG_RAX(%rsp) + /* pt_regs->ip = thread_info->sysenter_return */ + movq %r10,RIP(%rsp) + CFI_REL_OFFSET rip,RIP + movq $__USER32_CS,CS(%rsp) /* * no need to do an access_ok check here because rbp has been * 32bit zero extended @@ -171,10 +168,12 @@ sysenter_dispatch: jnz sysexit_audit sysexit_from_sys_call: andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS) - /* clear IF, that popfq doesn't enable interrupts early */ + /* clear IF, so that popfq won't enable interrupts early */ andl $~0x200,EFLAGS(%rsp) movl RIP(%rsp),%edx /* User %eip */ CFI_REGISTER rip,rdx + movl RSP(%rsp),%ecx /* User %esp */ + CFI_REGISTER rsp,rcx RESTORE_RSI_RDI /* pop everything except ss,rsp,rflags slots */ REMOVE_PTREGS_FROM_STACK 8*3 @@ -184,8 +183,6 @@ sysexit_from_sys_call: xorq %r11,%r11 popfq_cfi /*CFI_RESTORE rflags*/ - popq_cfi %rcx /* User %esp */ - CFI_REGISTER rsp,rcx TRACE_IRQS_ON /* * 32bit SYSEXIT restores eip from edx, esp from ecx. @@ -307,21 +304,21 @@ ENTRY(ia32_cstar_target) * disabled irqs and here we enable it straight after entry: */ ENABLE_INTERRUPTS(CLBR_NONE) - ALLOC_PTREGS_ON_STACK 6*8 /* space for orig_ax and iret frame */ - SAVE_C_REGS_EXCEPT_RCX_R891011 - movl %eax,%eax /* zero extension */ + movl %eax,%eax /* zero extension */ + ALLOC_PTREGS_ON_STACK 6*8 /* 6*8: space for orig_ax and iret frame */ movq %rax,ORIG_RAX(%rsp) movq %rcx,RIP(%rsp) CFI_REL_OFFSET rip,RIP - movq %rbp,RCX(%rsp) /* this lies slightly to ptrace */ - movl %ebp,%ecx movq $__USER32_CS,CS(%rsp) - movq $__USER32_DS,SS(%rsp) movq %r11,EFLAGS(%rsp) /*CFI_REL_OFFSET rflags,EFLAGS*/ movq %r8,RSP(%rsp) CFI_REL_OFFSET rsp,RSP - /* iret stack frame is complete now */ + movq $__USER32_DS,SS(%rsp) + /* iret frame is complete now */ + SAVE_C_REGS_EXCEPT_RCX_R891011 + movq %rbp,RCX(%rsp) /* this lies slightly to ptrace */ + movl %ebp,%ecx /* * no need to do an access_ok check here because r8 has been * 32bit zero extended @@ -447,11 +444,11 @@ ENTRY(ia32_syscall) */ ENABLE_INTERRUPTS(CLBR_NONE) movl %eax,%eax - pushq_cfi %rax /* store orig_ax */ cld /* note the registers are not zero extended to the sf. this could be a problem. */ - ALLOC_PTREGS_ON_STACK + ALLOC_PTREGS_ON_STACK 1*8 /* 1*8: space for orig_ax */ + movq %rax,ORIG_RAX(%rsp) SAVE_C_REGS_EXCEPT_R891011 orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS) -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
