mirror of
https://github.com/ipxe/ipxe
synced 2025-12-29 02:52:36 +03:00
Towards a(nother) new real-mode infrastructure, in which we take
advantage of the fact that we have to have a permanently-resident block in base memory.
This commit is contained in:
Michael Brown
@@ -1,30 +1,11 @@
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#include "virtaddr.h"
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#include "memsizes.h"
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#include "osdep.h"
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#include "etherboot.h"
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#include <gpxe/init.h>
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#include "relocate.h"
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#ifndef KEEP_IT_REAL
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/* by Eric Biederman */
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/* On some platforms etherboot is compiled as a shared library, and we use
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* the ELF pic support to make it relocateable. This works very nicely
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* for code, but since no one has implemented PIC data yet pointer
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* values in variables are a a problem. Global variables are a
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* pain but the return addresses on the stack are the worst. On these
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* platforms relocate_to will restart etherboot, to ensure the stack
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* is reinitialize and hopefully get the global variables
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* appropriately reinitialized as well.
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*
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*/
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#include <virtaddr.h>
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#include <registers.h>
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#include <memsizes.h>
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/*
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* relocate() must be called without any hardware resources pointing
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* at the current copy of Etherboot. The easiest way to achieve this
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* is to call relocate() from within arch_initialise(), before the NIC
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* gets touched in any way.
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* Originally by Eric Biederman
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*
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* Heavily modified by Michael Brown
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*
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*/
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@@ -40,14 +21,27 @@ extern char _max_align[];
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extern char _text[];
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extern char _end[];
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/* Post-relocation function table */
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static struct post_reloc_fn post_reloc_fns[0] __table_start(post_reloc_fn);
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static struct post_reloc_fn post_reloc_fns_end[0] __table_end(post_reloc_fn);
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/* within 1MB of 4GB is too close.
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* MAX_ADDR is the maximum address we can easily do DMA to.
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*
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* Not sure where this constraint comes from, but kept it from Eric's
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* old code - mcb30
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*/
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#define MAX_ADDR (0xfff00000UL)
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static void relocate ( void ) {
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/**
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* Relocate Etherboot
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*
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* @v ix86 x86 register dump from prefix
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* @ret ix86 x86 registers to return to prefix
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*
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* This copies Etherboot to a suitable location near the top of 32-bit
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* address space, and returns the physical address of the new location
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* to the prefix in %edi.
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*/
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void relocate ( struct i386_all_regs *ix86 ) {
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unsigned long addr, eaddr, size;
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unsigned i;
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struct post_reloc_fn *post_reloc_fn;
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/* Walk through the memory map and find the highest address
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* below 4GB that etherboot will fit into. Ensure etherboot
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@@ -183,25 +177,9 @@ static void relocate ( void ) {
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virt_to_phys ( _text ), virt_to_phys ( _end ),
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addr, addr + _end - _text );
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relocate_to ( addr );
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/* Note that we cannot make real-mode calls
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* (e.g. printf) at this point, because librm has just
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* been moved to high memory.
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*/
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/* Call any registered post-relocation functions.
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* librm has a post-relocation function to install a
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* new librm into base memory.
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*/
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for ( post_reloc_fn = post_reloc_fns;
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post_reloc_fn < post_reloc_fns_end ; post_reloc_fn++ ) {
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if ( post_reloc_fn->post_reloc )
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post_reloc_fn->post_reloc ();
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}
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memcpy ( phys_to_virt ( addr ), _text, _end - _text );
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}
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/* Let prefix know where the new copy is */
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ix86->regs.edi = addr;
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}
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INIT_FN ( INIT_RELOCATE, relocate, NULL, NULL );
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#endif /* ! KEEP_IT_REAL */
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@@ -7,164 +7,9 @@
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#include "virtaddr.h"
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.arch i386
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/****************************************************************************
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* GDT for initial transition to protected mode
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*
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* The segment values, PHYSICAL_CS et al, are defined in an external
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* header file virtaddr.h, since they need to be shared with librm.
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****************************************************************************
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*/
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.data
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.align 16
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gdt:
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gdt_limit: .word gdt_length - 1
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gdt_addr: .long 0
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.word 0 /* padding */
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.org gdt + PHYSICAL_CS
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physical_cs:
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/* 32 bit protected mode code segment, physical addresses */
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.word 0xffff,0
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.byte 0,0x9f,0xcf,0
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.org gdt + PHYSICAL_DS
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physical_ds:
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/* 32 bit protected mode data segment, physical addresses */
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.word 0xffff,0
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.byte 0,0x93,0xcf,0
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.org gdt + VIRTUAL_CS
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virtual_cs:
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/* 32 bit protected mode code segment, virtual addresses */
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.word 0xffff,0
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.byte 0,0x9f,0xcf,0
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.org gdt + VIRTUAL_DS
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virtual_ds:
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/* 32 bit protected mode data segment, virtual addresses */
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.word 0xffff,0
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.byte 0,0x93,0xcf,0
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#ifdef CONFIG_X86_64
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.org gdt + LONG_CS
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long_cs:
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/* 64bit long mode code segment, base 0 */
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.word 0xffff, 0
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.byte 0x00, 0x9f, 0xaf , 0x00
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.org gdt + LONG_DS
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long_ds:
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/* 64bit long mode data segment, base 0 */
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.word 0xffff, 0
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.byte 0x00, 0x93, 0xcf, 0x00
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#endif /* CONFIG_X86_64 */
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gdt_end:
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.equ gdt_length, gdt_end - gdt
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/* The virtual address offset */
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.globl virt_offset
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virt_offset: .long 0
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.text
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.code32
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/****************************************************************************
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* run_here (flat physical addressing, position-independent)
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*
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* Set up a GDT to run Etherboot at the current location with virtual
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* addressing. This call does not switch to virtual addresses or move
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* the stack pointer. The GDT will be located within the copy of
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* Etherboot. All registers are preserved.
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*
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* This gets called at startup and at any subsequent relocation of
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* Etherboot.
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*
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* Parameters: none
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****************************************************************************
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*/
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.globl run_here
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run_here:
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/* Preserve registers */
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pushl %eax
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pushl %ebp
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/* Find out where we're running */
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call 1f
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1: popl %ebp
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subl $1b, %ebp
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/* Store as virt_offset */
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movl %ebp, virt_offset(%ebp)
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/* Set segment base addresses in GDT */
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leal virtual_cs(%ebp), %eax
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pushl %eax
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pushl %ebp
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call set_seg_base
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popl %eax /* discard */
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popl %eax /* discard */
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/* Set physical location of GDT */
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leal gdt(%ebp), %eax
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movl %eax, gdt_addr(%ebp)
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/* Load the new GDT */
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lgdt gdt(%ebp)
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/* Reload new flat physical segment registers */
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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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/* Restore registers, convert return address to far return
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* address.
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*/
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popl %ebp
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movl $PHYSICAL_CS, %eax
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xchgl %eax, 4(%esp) /* cs now on stack, ret offset now in eax */
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xchgl %eax, 0(%esp) /* ret offset now on stack, eax restored */
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/* Return to caller, reloading %cs with new value */
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lret
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/****************************************************************************
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* set_seg_base (any addressing, position-independent)
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*
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* Set the base address of a pair of segments in the GDT. This relies
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* on the layout of the GDT being (CS,DS) pairs.
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*
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* Parameters:
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* uint32_t base_address
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* struct gdt_entry * code_segment
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* Returns:
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* none
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****************************************************************************
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*/
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.globl set_seg_base
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set_seg_base:
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pushl %eax
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pushl %ebx
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movl 12(%esp), %eax /* %eax = base address */
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movl 16(%esp), %ebx /* %ebx = &code_descriptor */
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movw %ax, (0+2)(%ebx) /* CS base bits 0-15 */
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movw %ax, (8+2)(%ebx) /* DS base bits 0-15 */
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shrl $16, %eax
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movb %al, (0+4)(%ebx) /* CS base bits 16-23 */
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movb %al, (8+4)(%ebx) /* DS base bits 16-23 */
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movb %ah, (0+7)(%ebx) /* CS base bits 24-31 */
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movb %ah, (8+7)(%ebx) /* DS base bits 24-31 */
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popl %ebx
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popl %eax
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ret
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/****************************************************************************
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* _virt_to_phys (virtual addressing)
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*
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@@ -254,64 +99,3 @@ _phys_to_virt:
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popl %eax
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popfl
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ret
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/****************************************************************************
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* relocate_to (virtual addressing)
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*
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* Relocate Etherboot to the specified address. The runtime image
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* (excluding the prefix, decompressor and compressed image) is copied
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* to a new location, and execution continues in the new copy. This
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* routine is designed to be called from C code.
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*
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* Parameters:
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* uint32_t new_phys_addr
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****************************************************************************
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*/
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.globl relocate_to
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relocate_to:
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/* Save the callee save registers */
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pushl %ebp
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pushl %esi
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pushl %edi
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/* Compute the physical source address and data length */
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movl $_text, %esi
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movl $_end, %ecx
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subl %esi, %ecx
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addl virt_offset, %esi
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/* Compute the physical destination address */
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movl 16(%esp), %edi
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/* Switch to flat physical addressing */
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call _virt_to_phys
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/* Do the copy */
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cld
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rep movsb
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/* Calculate offset to new image */
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subl %esi, %edi
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/* Switch to executing in new image */
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call 1f
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1: popl %ebp
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leal (2f-1b)(%ebp,%edi), %eax
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jmpl *%eax
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2:
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/* Switch to stack in new image */
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addl %edi, %esp
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/* Call run_here() to set up GDT */
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call run_here
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/* Switch to virtual addressing */
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call _phys_to_virt
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/* Restore the callee save registers */
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popl %edi
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popl %esi
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popl %ebp
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/* return */
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ret
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