From: Ard Biesheuvel <ardb@xxxxxxxxxx> In preparation for dropping the dependency on startup_32 entirely in the next patch, add the code that sets up the 1:1 mapping of the lower 4 GiB of system RAM to the mixed mode stub. The reload of CR3 after the long mode switch will be removed in a subsequent patch, when it is no longer needed. Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- arch/x86/boot/compressed/efi_mixed.S | 29 ++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S index 0b6b37b08f82..dca916c3e6f0 100644 --- a/arch/x86/boot/compressed/efi_mixed.S +++ b/arch/x86/boot/compressed/efi_mixed.S @@ -18,6 +18,7 @@ #include <asm/asm-offsets.h> #include <asm/msr.h> #include <asm/page_types.h> +#include <asm/pgtable_types.h> #include <asm/processor-flags.h> #include <asm/segment.h> #include <asm/setup.h> @@ -52,6 +53,9 @@ SYM_FUNC_START(startup_64_mixed_mode) mov 0(%rdx), %edi mov 4(%rdx), %esi + leaq (pte + 5 * PAGE_SIZE)(%rip), %rax + movq %rax, %cr3 // reload after startup_32 + /* Switch to the firmware's stack */ movl efi32_boot_sp(%rip), %esp andl $~7, %esp @@ -267,11 +271,32 @@ SYM_FUNC_START_LOCAL(efi32_entry) movl $_end - 1b, BP_init_size(%esi) subl $startup_32 - 1b, BP_init_size(%esi) + call 1f +1: pop %edi + /* Disable paging */ movl %cr0, %eax btrl $X86_CR0_PG_BIT, %eax movl %eax, %cr0 + /* Set up 1:1 mapping */ + leal (pte - 1b)(%edi), %eax + movl $_PAGE_PRESENT | _PAGE_RW | _PAGE_PSE, %ecx + leal (_PAGE_PRESENT | _PAGE_RW)(%eax), %edx +2: movl %ecx, (%eax) + addl $8, %eax + addl $PMD_SIZE, %ecx + jnc 2b + + movl $PAGE_SIZE, %ecx + .irpc l, 0123 + movl %edx, \l * 8(%eax) + addl %ecx, %edx + .endr + addl %ecx, %eax + movl %edx, (%eax) + movl %eax, %cr3 + jmp startup_32 SYM_FUNC_END(efi32_entry) @@ -322,3 +347,7 @@ SYM_DATA_LOCAL(efi32_boot_ds, .word 0) SYM_DATA_LOCAL(efi32_boot_sp, .long 0) SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0) SYM_DATA(efi_is64, .byte 1) + + .bss + .balign PAGE_SIZE +SYM_DATA_LOCAL(pte, .fill 6 * PAGE_SIZE, 1, 0) -- 2.48.1.362.g079036d154-goog
