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Commit 4c9c0e91 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
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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: default avatarDenys 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: default avatarIngo Molnar <mingo@kernel.org>
parent 4416c5a6

arch/x86/ia32/ia32entry.S

+46 −36
Original line number Diff line number Diff line
@@ -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



	/* 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

	/* Store orig_ax */

	pushq_cfi %rax

	/* Construct the rest of "struct pt_regs" */

	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