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x86: add wrapper to run 32bit code in 64bit long mode

pull/530/head
Marco Oliverio 2024-09-10 18:45:25 +02:00 committed by Daniele Lacamera
parent 6358153372
commit b8a81de965
2 changed files with 87 additions and 0 deletions
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1
include/x86/common.h
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@ -68,4 +68,5 @@ int cpuid_is_1gb_page_supported();
void switch_to_long_mode(uint64_t *entry, uint32_t page_table); void switch_to_long_mode(uint64_t *entry, uint32_t page_table);
void x86_log_memory_load(uint32_t start, uint32_t end, const char *name); void x86_log_memory_load(uint32_t start, uint32_t end, const char *name);
void hlt(); void hlt();
int x86_run_fsp_32bit(void* api, void* arg);
#endif /* COMMON_H */ #endif /* COMMON_H */

86
src/x86/common.c
View File

@ -35,6 +35,7 @@
#include <stdint.h> #include <stdint.h>
#include <x86/common.h> #include <x86/common.h>
#include <x86/gdt.h>
#define barrier() __asm__ __volatile__ ("":::"memory"); #define barrier() __asm__ __volatile__ ("":::"memory");
@ -371,4 +372,89 @@ void x86_log_memory_load(uint32_t start, uint32_t end, const char *name)
{ {
wolfBoot_printf("mem: [ 0x%x, 0x%x ] - %s (0x%x) \n\r", start, end, name, end - start); wolfBoot_printf("mem: [ 0x%x, 0x%x ] - %s (0x%x) \n\r", start, end, name, end - start);
} }
#if !defined(BUILD_LOADER_STAGE1)
int x86_run_fsp_32bit(void* api, void* arg)
{
uint32_t status;
__asm__ volatile (
/* arg on the stack, will be used as arg */
"mov %[arg], %%rax\n"
"shl $32, %%rax\n"
"or %[api], %%rax\n"
"push %%rax\n"
"push %[SEG_COMP]\n"
"lea (1f), %%rax\n"
"push %%rax\n"
"retfq\n"
"1:\n"
/* we are now in compatibility mode */
".code32\n"
/* disable paging */
"mov %%cr0, %%eax\n"
"mov %[PG], %%edx\n"
"not %%edx\n"
"and %%edx, %%eax\n"
"mov %%eax, %%cr0\n"
/* disable EFER.LME */
"mov $0xc0000080, %%ecx\n"
"rdmsr\n"
"mov %[LME], %%ecx\n"
"not %%ecx\n"
"and %%ecx, %%eax\n"
"mov $0xc0000080, %%ecx\n"
"wrmsr\n"
/* disable PAE */
"mov %%cr4, %%eax\n"
"mov %[PAE], %%edx\n"
"not %%edx\n"
"and %%edx, %%eax\n"
"mov %%eax, %%cr4\n"
/* get api from stack */
"pop %%eax\n"
"call *%%eax\n"
/* remove parameter from the stack */
"add $4, %%esp\n"
/* save status to ebx */
"mov %%eax, %%ebx\n"
/* enable PAE */
"mov %%cr4, %%eax\n"
"or %[PAE], %%eax\n"
"mov %%eax, %%cr4\n"
/* enable EFER_LME */
"mov $0xc0000080, %%ecx\n"
"rdmsr\n"
"or %[LME], %%eax\n"
"mov $0xc0000080, %%ecx\n"
"wrmsr\n"
/* setup far pointer on the stack */
"push %[SEG_LONG]\n"
"push $2f\n"
/* enable paging */
"mov %%cr0, %%eax\n"
"or %[PG], %%eax\n"
"mov %%eax, %%cr0\n"
"retf\n"
"2:\n"
/* back in long mode */
".code64\n"
/* save status */
"mov %%ebx, %[status]\n"
:[status]"=m"(status)
:[SEG_COMP]"i"(GDT_CS_32BIT_COMPAT),
[SEG_LONG]"i"(GDT_CS_64BIT),
[PG]"i"(CR0_PG_BIT),
[LME]"i"(IA32_EFER_LME),
[PAE]"i"(CR4_PAE_BIT),
[api]"r"(api),
[arg]"r"(arg)
: "rax", "rbx", "rcx", "rdx");
return status;
}
#else
int x86_run_fsp_32bit(void* api, void* arg)
{
return 0;
}
#endif /* !STAGE1 */
#endif /* COMMON_H_ */ #endif /* COMMON_H_ */