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ramstage: prepare for relocation

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The current ramstage code contains uses of symbols that cause issues
when the ramstage is relocatable. There are 2 scenarios resolved by this
patch:

1. Absolute symbols that are actually sizes/limits. The symbols are
   problematic when relocating a program because there is no way to
   distinguish a symbol that shouldn't be relocated and one that can.
   The only way to handle these symbols is to write a program to post
   process the relocations and keep a whitelist of ones that shouldn't
   be relocated. I don't believe that is a route that should be taken
   so fix the users of these sizes/limits encoded as absolute symbols
   to calculate the size at runtime or dereference a variable in memory
   containing the size/limit.

2. Absoulte symbols that were relocated to a fixed address. These
   absolute symbols are generated by assembly files to be placed at a
   fixed location. Again, these symbols are problematic because one
   can't distinguish a symbol that can't be relocated. The symbols
   are again resolved at runtime to allow for proper relocation.

For the symbols defining a size either use 2 symbols and calculate the
difference or provide a variable in memory containing the size.

Change-Id: I1ef2bfe6fd531308218bcaac5dcccabf8edf932c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2789
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
This commit is contained in:
Aaron Durbin
2013-02-08 16:56:51 -06:00
committed by Stefan Reinauer
parent e8c866ad45
commit a146d58ca0
9 changed files with 76 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
src/device/oprom/realmode/x86.c
View File

@@ -36,16 +36,37 @@
#include <boot/coreboot_tables.h>
#include <device/pci_ids.h>
/* The following symbols cannot be used directly. They need to be fixed up
* to point to the correct address location after the code has been copied
* to REALMODE_BASE. Absolute symbols are not used because those symbols are
* relocated when a relocatable ramstage is enabled.
*/
extern unsigned char __realmode_call, __realmode_interrupt;
extern unsigned char __realmode_buffer;
#define PTR_TO_REAL_MODE(sym)\
(void *)(REALMODE_BASE + ((char *)&(sym) - (char *)&__realmode_code))
/* to have a common register file for interrupt handlers */
X86EMU_sysEnv _X86EMU_env;
void (*realmode_call)(u32 addr, u32 eax, u32 ebx, u32 ecx, u32 edx,
u32 esi, u32 edi) asmlinkage =
(void *)&__realmode_call;
u32 esi, u32 edi) asmlinkage;
void (*realmode_interrupt)(u32 intno, u32 eax, u32 ebx, u32 ecx, u32 edx,
u32 esi, u32 edi) asmlinkage =
(void *)&__realmode_interrupt;
u32 esi, u32 edi) asmlinkage;
static void setup_realmode_code(void)
{
memcpy(REALMODE_BASE, &__realmode_code, __realmode_code_size);
/* Ensure the global pointers are relocated properly. */
realmode_call = PTR_TO_REAL_MODE(__realmode_call);
realmode_interrupt = PTR_TO_REAL_MODE(__realmode_interrupt);
printk(BIOS_SPEW, "Real mode stub @%p: %d bytes\n", REALMODE_BASE,
__realmode_code_size);
}
static void setup_rombios(void)
{
@@ -149,7 +170,7 @@ static void write_idt_stub(void *target, u8 intnum)
{
unsigned char *codeptr;
codeptr = (unsigned char *) target;
memcpy(codeptr, &__idt_handler, (size_t)&__idt_handler_size);
memcpy(codeptr, &__idt_handler, __idt_handler_size);
codeptr[3] = intnum; /* modify int# in the code stub. */
}
@@ -163,7 +184,7 @@ static void setup_realmode_idt(void)
*/
for (i = 0; i < 256; i++) {
idts[i].cs = 0;
idts[i].offset = 0x1000 + (i * (u32)&__idt_handler_size);
idts[i].offset = 0x1000 + (i * __idt_handler_size);
write_idt_stub((void *)((u32 )idts[i].offset), i);
}
@@ -204,7 +225,7 @@ static u8 vbe_get_mode_info(vbe_mode_info_t * mi)
{
printk(BIOS_DEBUG, "VBE: Getting information about VESA mode %04x\n",
mi->video_mode);
char *buffer = (char *)&__buffer;
char *buffer = PTR_TO_REAL_MODE(__realmode_buffer);
u16 buffer_seg = (((unsigned long)buffer) >> 4) & 0xff00;
u16 buffer_adr = ((unsigned long)buffer) & 0xffff;
realmode_interrupt(0x10, VESA_GET_MODE_INFO, 0x0000,
@@ -312,9 +333,8 @@ void run_bios(struct device *dev, unsigned long addr)
/* Set up real-mode IDT */
setup_realmode_idt();
memcpy(REALMODE_BASE, &__realmode_code, (size_t)&__realmode_code_size);
printk(BIOS_SPEW, "Real mode stub @%p: %d bytes\n", REALMODE_BASE,
(u32)&__realmode_code_size);
/* Make sure the code is placed. */
setup_realmode_code();
printk(BIOS_DEBUG, "Calling Option ROM...\n");
/* TODO ES:DI Pointer to System BIOS PnP Installation Check Structure */
@@ -366,9 +386,8 @@ void do_vsmbios(void)
/* Setting up realmode IDT */
setup_realmode_idt();
memcpy(REALMODE_BASE, &__realmode_code, (size_t)&__realmode_code_size);
printk(BIOS_SPEW, "VSA: Real mode stub @%p: %d bytes\n", REALMODE_BASE,
(u32)&__realmode_code_size);
/* Make sure the code is placed. */
setup_realmode_code();
if ((unsigned int)cbfs_load_stage(CBFS_DEFAULT_MEDIA, "vsa") !=
VSA2_ENTRY_POINT) {

8
src/device/oprom/realmode/x86.h
View File

@@ -32,10 +32,10 @@ struct realmode_idt {
void x86_exception(struct eregs *info);
/* From x86_asm.S */
extern unsigned char __idt_handler, __idt_handler_size;
extern unsigned char __realmode_code, __realmode_code_size;
extern unsigned char __realmode_call, __realmode_interrupt;
extern unsigned char __buffer;
extern unsigned char __idt_handler;
extern unsigned int __idt_handler_size;
extern unsigned char __realmode_code;
extern unsigned int __realmode_code_size;
extern void (*realmode_call)(u32 addr, u32 eax, u32 ebx, u32 ecx, u32 edx,
u32 esi, u32 edi) asmlinkage;

15
src/device/oprom/realmode/x86_asm.S
View File

@@ -36,7 +36,8 @@ __idt_handler:
movb $0, %al /* This instruction gets modified */
ljmp $0, $__interrupt_handler_16bit
.globl __idt_handler_size
__idt_handler_size = ( . - __idt_handler)
__idt_handler_size:
.long . - __idt_handler
/* In order to be independent of coreboot's position in RAM
@@ -47,7 +48,6 @@ __idt_handler_size = ( . - __idt_handler)
__realmode_code:
/* Realmode IDT pointer structure. */
.globl __realmode_idt
__realmode_idt = RELOCATED(.)
.word 1023 /* 16 bit limit */
.long 0 /* 24 bit base */
@@ -67,13 +67,13 @@ __registers = RELOCATED(.)
.long 0 /* 20 - EDI */
/* 256 byte buffer, used by int10 */
.globl __buffer
__buffer = RELOCATED(.)
.globl __realmode_buffer
__realmode_buffer:
.skip 256
.code32
.globl __realmode_call
__realmode_call = RELOCATED(.)
__realmode_call:
/* save all registers to the stack */
pusha
pushf
@@ -204,7 +204,7 @@ __lcall_instr = RELOCATED(.)
ret
.globl __realmode_interrupt
__realmode_interrupt = RELOCATED(.)
__realmode_interrupt:
/* save all registers to the stack */
pusha
pushf
@@ -408,6 +408,7 @@ __interrupt_handler_16bit = RELOCATED(.)
iret
.globl __realmode_code_size
__realmode_code_size = (. - __realmode_code)
__realmode_code_size:
.long . - __realmode_code
.code32