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Date: Thu, 2 Apr 2015 05:25:21 -0700 From: tip-bot for Denys Vlasenko <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: fweisbec@...il.com, wad@...omium.org, tglx@...utronix.de, rostedt@...dmis.org, dvlasenk@...hat.com, ast@...mgrid.com, hpa@...or.com, keescook@...omium.org, luto@...capital.net, bp@...en8.de, linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org, mingo@...nel.org, oleg@...hat.com Subject: [tip:x86/asm] x86/asm/entry/32: Use smaller PUSH instructions instead of MOV, to build 'pt_regs' on stack Commit-ID: 4c9c0e919fef05b3bc6a8aff1db7a31b2ba4f4b6 Gitweb: http://git.kernel.org/tip/4c9c0e919fef05b3bc6a8aff1db7a31b2ba4f4b6 Author: Denys Vlasenko <dvlasenk@...hat.com> AuthorDate: Tue, 31 Mar 2015 19:00:04 +0200 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Wed, 1 Apr 2015 13:17:38 +0200 x86/asm/entry/32: Use smaller PUSH instructions instead of MOV, to build 'pt_regs' on stack This mimics the recent similar 64-bit change. Saves ~110 bytes of code. Patch was run-tested on 32 and 64 bits, Intel and AMD CPU. I also looked at the diff of entry_64.o disassembly, to have a different view of the changes. Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com> Cc: Alexei Starovoitov <ast@...mgrid.com> Cc: Andy Lutomirski <luto@...capital.net> Cc: Borislav Petkov <bp@...en8.de> Cc: Frederic Weisbecker <fweisbec@...il.com> Cc: H. Peter Anvin <hpa@...or.com> Cc: Kees Cook <keescook@...omium.org> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Oleg Nesterov <oleg@...hat.com> Cc: Steven Rostedt <rostedt@...dmis.org> Cc: Will Drewry <wad@...omium.org> Link: http://lkml.kernel.org/r/1427821211-25099-2-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar <mingo@...nel.org> --- arch/x86/ia32/ia32entry.S | 82 ++++++++++++++++++++++++++--------------------- 1 file changed, 46 insertions(+), 36 deletions(-) diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index dec8c1d..8d01cce 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -126,26 +126,27 @@ ENTRY(ia32_sysenter_target) movl %ebp, %ebp movl %eax, %eax - /* Construct iret frame (ss,rsp,rflags,cs,rip) */ - pushq_cfi $__USER32_DS - /*CFI_REL_OFFSET ss,0*/ - pushq_cfi %rbp - CFI_REL_OFFSET rsp,0 - pushfq_cfi - /*CFI_REL_OFFSET rflags,0*/ - movl ASM_THREAD_INFO(TI_sysenter_return, %rsp, 3*8), %r10d + movl ASM_THREAD_INFO(TI_sysenter_return, %rsp, 0), %r10d CFI_REGISTER rip,r10 - pushq_cfi $__USER32_CS - /*CFI_REL_OFFSET cs,0*/ - /* 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" */ + + /* Construct struct pt_regs on stack */ + pushq_cfi $__USER32_DS /* pt_regs->ss */ + pushq_cfi %rbp /* pt_regs->sp */ + CFI_REL_OFFSET rsp,0 + pushfq_cfi /* pt_regs->flags */ + pushq_cfi $__USER32_CS /* pt_regs->cs */ + pushq_cfi %r10 /* pt_regs->ip = thread_info->sysenter_return */ + CFI_REL_OFFSET rip,0 + pushq_cfi_reg rax /* pt_regs->orig_ax */ + pushq_cfi_reg rdi /* pt_regs->di */ + pushq_cfi_reg rsi /* pt_regs->si */ + pushq_cfi_reg rdx /* pt_regs->dx */ + pushq_cfi_reg rcx /* pt_regs->cx */ + pushq_cfi_reg rax /* pt_regs->ax */ cld - ALLOC_PT_GPREGS_ON_STACK - SAVE_C_REGS_EXCEPT_R891011 + sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ + CFI_ADJUST_CFA_OFFSET 10*8 + /* * no need to do an access_ok check here because rbp has been * 32bit zero extended @@ -334,20 +335,24 @@ ENTRY(ia32_cstar_target) /* Zero-extending 32-bit regs, do not remove */ movl %eax,%eax - ALLOC_PT_GPREGS_ON_STACK 6*8 /* 6*8: space for orig_ax and iret frame */ - SAVE_C_REGS_EXCEPT_RCX_R891011 - movq %rax,ORIG_RAX(%rsp) - movq %rcx,RIP(%rsp) - CFI_REL_OFFSET rip,RIP - movq %rbp,RCX(%rsp) /* this lies slightly to ptrace */ + /* Construct struct pt_regs on stack */ + pushq_cfi $__USER32_DS /* pt_regs->ss */ + pushq_cfi %r8 /* pt_regs->sp */ + CFI_REL_OFFSET rsp,0 + pushq_cfi %r11 /* pt_regs->flags */ + pushq_cfi $__USER32_CS /* pt_regs->cs */ + pushq_cfi %rcx /* pt_regs->ip */ + CFI_REL_OFFSET rip,0 + pushq_cfi_reg rax /* pt_regs->orig_ax */ + pushq_cfi_reg rdi /* pt_regs->di */ + pushq_cfi_reg rsi /* pt_regs->si */ + pushq_cfi_reg rdx /* pt_regs->dx */ + pushq_cfi_reg rbp /* pt_regs->cx */ 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 */ + pushq_cfi_reg rax /* pt_regs->ax */ + sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ + CFI_ADJUST_CFA_OFFSET 10*8 + /* * no need to do an access_ok check here because r8 has been * 32bit zero extended @@ -478,12 +483,17 @@ ENTRY(ia32_syscall) /* Zero-extending 32-bit regs, do not remove */ movl %eax,%eax - pushq_cfi %rax /* store orig_ax */ + /* Construct struct pt_regs on stack (iret frame is already on stack) */ + pushq_cfi_reg rax /* pt_regs->orig_ax */ + pushq_cfi_reg rdi /* pt_regs->di */ + pushq_cfi_reg rsi /* pt_regs->si */ + pushq_cfi_reg rdx /* pt_regs->dx */ + pushq_cfi_reg rcx /* pt_regs->cx */ + pushq_cfi_reg rax /* pt_regs->ax */ cld - /* note the registers are not zero extended to the sf. - this could be a problem. */ - ALLOC_PT_GPREGS_ON_STACK - SAVE_C_REGS_EXCEPT_R891011 + sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ + CFI_ADJUST_CFA_OFFSET 10*8 + orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jnz ia32_tracesys -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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