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x86/asm/entry/32: Use smaller PUSH instructions instead of MOV, to build 'pt_regs' on stack

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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@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1427821211-25099-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Denys Vlasenko 2015-03-31 19:00:04 +02:00 committed by Ingo Molnar
parent 4416c5a6da
commit 4c9c0e919f
1 changed files with 46 additions and 36 deletions
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82
arch/x86/ia32/ia32entry.S
View file

@ -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