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[librm] Do not preserve flags unnecessarily 

No callers of prot_to_phys, phys_to_prot, or intr_to_prot require the
flags to be preserved.  Remove the unnecessary pushfl/popfl pairs.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2016-02-21 01:01:28 +00:00
parent ea203e4fe1
commit 5fbfe50ccb
1 changed files with 11 additions and 17 deletions
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28
src/arch/x86/transitions/librm.S
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@ -506,7 +506,7 @@ rm_gdtr:
*
* Switch from 32-bit protected mode with physical addresses to 32-bit
* protected mode with virtual addresses. %esp is adjusted to a
* virtual address. All other registers and flags are preserved.
* virtual address. All other registers are preserved.
*
* The return address for this function should be a 32-bit physical
* (sic) address.
@ -517,8 +517,7 @@ rm_gdtr:
.code32
.globl phys_to_prot
phys_to_prot:
/* Preserve registers and flags */
pushfl
/* Preserve registers */
pushl %eax
pushl %ebp
@ -537,12 +536,11 @@ phys_to_prot:
subl %ebp, %esp
/* Adjust return address to a virtual address */
subl %ebp, 12(%esp)
subl %ebp, 8(%esp)
/* Restore registers and flags, and return */
/* Restore registers and return */
popl %ebp
popl %eax
popfl
ret
/* Expose as _phys_to_virt for use by COMBOOT */
@ -554,7 +552,7 @@ phys_to_prot:
*
* Switch from 32-bit protected mode with virtual addresses to 32-bit
* protected mode with physical addresses. %esp is adjusted to a
* physical address. All other registers and flags are preserved.
* physical address. All other registers are preserved.
*
* The return address for this function should be a 32-bit virtual
* (sic) address.
@ -564,14 +562,13 @@ phys_to_prot:
.section ".text.prot_to_phys", "ax", @progbits
.code32
prot_to_phys:
/* Preserve registers and flags */
pushfl
/* Preserve registers */
pushl %eax
pushl %ebp
/* Adjust return address to a physical address */
movl VIRTUAL(virt_offset), %ebp
addl %ebp, 12(%esp)
addl %ebp, 8(%esp)
/* Switch to physical code segment */
cli
@ -589,10 +586,9 @@ prot_to_phys:
movw %ax, %ss
addl %ebp, %esp
/* Restore registers and flags, and return */
/* Restore registers and return */
popl %ebp
popl %eax
popfl
ret
/* Expose as _virt_to_phys for use by COMBOOT */
@ -605,7 +601,7 @@ prot_to_phys:
* Switch from 32-bit protected mode with a virtual code segment and
* either a physical or virtual stack segment to 32-bit protected mode
* with normal virtual addresses. %esp is adjusted if necessary to a
* virtual address. All other registers and flags are preserved.
* virtual address. All other registers are preserved.
*
* The return address for this function should be a 32-bit virtual
* address.
@ -616,8 +612,7 @@ prot_to_phys:
.code32
.globl intr_to_prot
intr_to_prot:
/* Preserve registers and flags */
pushfl
/* Preserve registers */
pushl %eax
/* Check whether stack segment is physical or virtual */
@ -636,9 +631,8 @@ intr_to_prot:
movw %ax, %ss
subl VIRTUAL(virt_offset), %esp
1:
/* Restore registers and flags, and return */
/* Restore registers and return */
popl %eax
popfl
ret
/* Expose as _intr_to_virt for use by GDB */