[librm] Add phys_call() wrapper for calling code with physical addressing
Add a phys_call() wrapper function (analogous to the existing
real_call() wrapper function) for calling code with flat physical
addressing, and use this wrapper within the PHYS_CODE() macro.
Move the relevant functionality inside librm.S, where it more
naturally belongs.
The COMBOOT code currently uses explicit calls to _virt_to_phys and
_phys_to_virt. These will need to be rewritten if our COMBOOT support
is ever generalised to be able to run in a 64-bit build.
Specifically:
- com32_exec_loop() should be restructured to use PHYS_CODE()
- com32_wrapper.S should be restructured to use an equivalent of
prot_call(), passing parameters via a struct i386_all_regs
- there appears to be no need for com32_wrapper.S to switch between
external and internal stacks; this could be omitted to simplify
the design.
For now, librm.S continues to expose _virt_to_phys and _phys_to_virt
for use by com32.c and com32_wrapper.S. Similarly, librm.S continues
to expose _intr_to_virt for use by gdbidt.S.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
parent
a4923354e3
commit
ea203e4fe1
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@ -1,145 +0,0 @@
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/*
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* Functions to support the virtual addressing method of relocation
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* that Etherboot uses.
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
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#include "librm.h"
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.arch i386
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.text
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.code32
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/****************************************************************************
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* _virt_to_phys (virtual addressing)
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*
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* Switch from virtual to flat physical addresses. %esp is adjusted
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* to a physical value. Segment registers are set to flat physical
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* selectors. All other registers are preserved. Flags are
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* preserved.
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*
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* Parameters: none
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* Returns: none
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****************************************************************************
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*/
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.globl _virt_to_phys
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_virt_to_phys:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Change return address to a physical address */
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movl VIRTUAL(virt_offset), %ebp
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addl %ebp, 12(%esp)
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/* Switch to physical code segment */
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cli
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pushl $PHYSICAL_CS
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leal VIRTUAL(1f)(%ebp), %eax
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pushl %eax
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lret
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1:
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/* Reload other segment registers and adjust %esp */
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movl $PHYSICAL_DS, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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movl %eax, %ss
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addl %ebp, %esp
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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/****************************************************************************
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* _phys_to_virt (flat physical addressing)
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*
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* Switch from flat physical to virtual addresses. %esp is adjusted
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* to a virtual value. Segment registers are set to virtual
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* selectors. All other registers are preserved. Flags are
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* preserved.
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*
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* Parameters: none
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* Returns: none
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****************************************************************************
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*/
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.globl _phys_to_virt
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_phys_to_virt:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Switch to virtual code segment */
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cli
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ljmp $VIRTUAL_CS, $VIRTUAL(1f)
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1:
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/* Reload data segment registers */
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movl $VIRTUAL_DS, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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/* Reload stack segment and adjust %esp */
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movl VIRTUAL(virt_offset), %ebp
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movl %eax, %ss
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subl %ebp, %esp
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/* Change the return address to a virtual address */
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subl %ebp, 12(%esp)
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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/****************************************************************************
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* _intr_to_virt (virtual code segment, virtual or physical stack segment)
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*
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* Switch from virtual code segment with either a virtual or physical
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* stack segment to using virtual addressing. %esp is adjusted if
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* necessary to a virtual value. Segment registers are set to virtual
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* selectors. All other registers are preserved. Flags are
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* preserved.
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*
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* Parameters: none
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* Returns: none
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****************************************************************************
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*/
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.globl _intr_to_virt
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_intr_to_virt:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Check whether stack segment is physical or virtual */
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movl %ss, %eax
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cmpw $VIRTUAL_DS, %ax
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movl $VIRTUAL_DS, %eax
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/* Reload data segment registers */
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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/* Reload stack segment and adjust %esp if necessary */
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je 1f
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movl VIRTUAL(virt_offset), %ebp
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movl %eax, %ss
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subl %ebp, %esp
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1:
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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@ -250,11 +250,16 @@ extern void remove_user_from_rm_stack ( userptr_t data, size_t size );
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/* PHYS_CODE: declare a fragment of code that executes in flat physical mode */
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#define PHYS_CODE( asm_code_str ) \
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"call _virt_to_phys\n\t" \
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"push $1f\n\t" \
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"call phys_call\n\t" \
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".section \".text.phys\", \"ax\", @progbits\n\t"\
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".code32\n\t" \
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"\n1:\n\t" \
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asm_code_str \
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"call _phys_to_virt\n\t" \
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CODE_DEFAULT "\n\t"
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"\n\t" \
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"ret\n\t" \
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CODE_DEFAULT "\n\t" \
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".previous\n\t"
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/** Number of interrupts */
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#define NUM_INT 256
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@ -501,6 +501,150 @@ rm_gdtr:
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.word 0 /* Limit */
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.long 0 /* Base */
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/****************************************************************************
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* phys_to_prot (protected-mode near call, 32-bit physical return address)
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*
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* Switch from 32-bit protected mode with physical addresses to 32-bit
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* protected mode with virtual addresses. %esp is adjusted to a
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* virtual address. All other registers and flags are preserved.
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*
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* The return address for this function should be a 32-bit physical
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* (sic) address.
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*
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****************************************************************************
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*/
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.section ".text.phys_to_prot", "ax", @progbits
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.code32
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.globl phys_to_prot
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phys_to_prot:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Switch to virtual code segment */
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cli
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ljmp $VIRTUAL_CS, $VIRTUAL(1f)
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1:
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/* Switch to virtual data segment and adjust %esp */
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movw $VIRTUAL_DS, %ax
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %fs
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movw %ax, %gs
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movw %ax, %ss
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movl VIRTUAL(virt_offset), %ebp
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subl %ebp, %esp
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/* Adjust return address to a virtual address */
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subl %ebp, 12(%esp)
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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/* Expose as _phys_to_virt for use by COMBOOT */
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.globl _phys_to_virt
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.equ _phys_to_virt, phys_to_prot
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/****************************************************************************
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* prot_to_phys (protected-mode near call, 32-bit virtual return address)
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*
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* Switch from 32-bit protected mode with virtual addresses to 32-bit
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* protected mode with physical addresses. %esp is adjusted to a
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* physical address. All other registers and flags are preserved.
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*
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* The return address for this function should be a 32-bit virtual
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* (sic) address.
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*
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****************************************************************************
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*/
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.section ".text.prot_to_phys", "ax", @progbits
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.code32
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prot_to_phys:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Adjust return address to a physical address */
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movl VIRTUAL(virt_offset), %ebp
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addl %ebp, 12(%esp)
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/* Switch to physical code segment */
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cli
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pushl $PHYSICAL_CS
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leal VIRTUAL(1f)(%ebp), %eax
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pushl %eax
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lret
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1:
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/* Switch to physical data segment and adjust %esp */
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movw $PHYSICAL_DS, %ax
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %fs
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movw %ax, %gs
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movw %ax, %ss
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addl %ebp, %esp
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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/* Expose as _virt_to_phys for use by COMBOOT */
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.globl _virt_to_phys
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.equ _virt_to_phys, prot_to_phys
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/****************************************************************************
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* intr_to_prot (protected-mode near call, 32-bit virtual return address)
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*
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* Switch from 32-bit protected mode with a virtual code segment and
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* either a physical or virtual stack segment to 32-bit protected mode
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* with normal virtual addresses. %esp is adjusted if necessary to a
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* virtual address. All other registers and flags are preserved.
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*
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* The return address for this function should be a 32-bit virtual
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* address.
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*
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****************************************************************************
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*/
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.section ".text.intr_to_prot", "ax", @progbits
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.code32
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.globl intr_to_prot
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intr_to_prot:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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/* Check whether stack segment is physical or virtual */
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movw %ss, %ax
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cmpw $VIRTUAL_DS, %ax
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movw $VIRTUAL_DS, %ax
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/* Reload data segment registers */
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %fs
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movw %ax, %gs
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/* Reload stack segment and adjust %esp if necessary */
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je 1f
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movw %ax, %ss
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subl VIRTUAL(virt_offset), %esp
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1:
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/* Restore registers and flags, and return */
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popl %eax
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popfl
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ret
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/* Expose as _intr_to_virt for use by GDB */
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.globl _intr_to_virt
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.equ _intr_to_virt, intr_to_prot
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/****************************************************************************
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* prot_call (real-mode near call, 16-bit real-mode near return address)
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*
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@ -539,6 +683,7 @@ PC_OFFSET_IDT: .space 6
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PC_OFFSET_IX86: .space SIZEOF_I386_ALL_REGS
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PC_OFFSET_PADDING: .space 2 /* for alignment */
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PC_OFFSET_RETADDR: .space 2
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PC_OFFSET_PARAMS:
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PC_OFFSET_FUNCTION: .space 4
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PC_OFFSET_END:
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.previous
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@ -601,7 +746,9 @@ pc_rmode:
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addr32 movl -20(%esp), %esp
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popfl
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popfw /* padding */
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ret $4
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/* Return and discard function parameters */
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ret $( PC_OFFSET_END - PC_OFFSET_PARAMS )
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/****************************************************************************
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* real_call (protected-mode near call, 32-bit virtual return address)
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@ -620,7 +767,7 @@ pc_rmode:
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* See librm.h and realmode.h for details and examples.
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*
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* Parameters:
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* (32-bit) near pointer to real-mode function to call
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* function : offset within .text16 of real-mode function to call
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*
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* Returns: none
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****************************************************************************
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@ -629,6 +776,7 @@ pc_rmode:
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RC_OFFSET_REGS: .space SIZEOF_I386_REGS
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RC_OFFSET_REGS_END:
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RC_OFFSET_RETADDR: .space 4
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RC_OFFSET_PARAMS:
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RC_OFFSET_FUNCTION: .space 4
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RC_OFFSET_END:
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.previous
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@ -665,9 +813,11 @@ rc_rmode:
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.section ".text.real_call", "ax", @progbits
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.code32
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rc_pmode:
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/* Restore registers and return */
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/* Restore registers */
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popal
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ret $4
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/* Return and discard function parameters */
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ret $( RC_OFFSET_END - RC_OFFSET_PARAMS )
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/* Function vector, used because "call xx(%sp)" is not a valid
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@ -684,6 +834,55 @@ rm_default_gdtr_idtr:
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.word 0x03ff /* Interrupt descriptor table limit */
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.long 0 /* Interrupt descriptor table base */
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/****************************************************************************
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* phys_call (protected-mode near call, 32-bit virtual return address)
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*
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* Call a function with flat 32-bit physical addressing
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*
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* The non-segment register values will be passed directly to the
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* function. The segment registers will be set for flat 32-bit
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* physical addressing. The non-segment register values set by the
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* function will be passed back to the caller.
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*
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* librm.h defines a convenient macro PHYS_CODE() for using phys_call.
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*
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* Parameters:
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* function : virtual (sic) address of function to call
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*
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****************************************************************************
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*/
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.struct 0
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PHC_OFFSET_RETADDR: .space 4
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PHC_OFFSET_PARAMS:
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PHC_OFFSET_FUNCTION: .space 4
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PHC_OFFSET_END:
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.previous
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.section ".text.phys_call", "ax", @progbits
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.code32
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.globl phys_call
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phys_call:
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/* Adjust function pointer to a physical address */
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pushl %ebp
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movl VIRTUAL(virt_offset), %ebp
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addl %ebp, ( PHC_OFFSET_FUNCTION + 4 /* saved %ebp */ )(%esp)
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popl %ebp
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/* Switch to physical addresses */
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call prot_to_phys
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/* Call function */
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call *PHC_OFFSET_FUNCTION(%esp)
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/* For sanity's sake, clear the direction flag as soon as possible */
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cld
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/* Switch to virtual addresses */
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call phys_to_prot
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/* Return and discard function parameters */
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ret $( PHC_OFFSET_END - PHC_OFFSET_PARAMS )
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/****************************************************************************
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* flatten_real_mode (real-mode near call)
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*
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@ -733,7 +932,7 @@ interrupt_wrapper:
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pushl %esp
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/* Switch to virtual addressing */
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call _intr_to_virt
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call intr_to_prot
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/* Expand IRQ number to whole %eax register */
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movzbl %al, %eax
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Reference in New Issue