diff options
Diffstat (limited to 'arch/x86/boot/compressed/head_32.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_32.S | 207 |
1 files changed, 79 insertions, 128 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 1e3184f6072f..1cfe9802a42f 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ /* * linux/boot/head.S * @@ -29,67 +30,22 @@ #include <asm/page_types.h> #include <asm/boot.h> #include <asm/asm-offsets.h> +#include <asm/bootparam.h> - __HEAD -ENTRY(startup_32) -#ifdef CONFIG_EFI_STUB - jmp preferred_addr - - /* - * We don't need the return address, so set up the stack so - * efi_main() can find its arguments. - */ -ENTRY(efi_pe_entry) - add $0x4, %esp - - call make_boot_params - cmpl $0, %eax - je 1f - movl 0x4(%esp), %esi - movl (%esp), %ecx - pushl %eax - pushl %esi - pushl %ecx - sub $0x4, %esp - -ENTRY(efi_stub_entry) - add $0x4, %esp - call efi_main - cmpl $0, %eax - movl %eax, %esi - jne 2f -1: - /* EFI init failed, so hang. */ - hlt - jmp 1b -2: - call 3f -3: - popl %eax - subl $3b, %eax - subl BP_pref_address(%esi), %eax - add BP_code32_start(%esi), %eax - leal preferred_addr(%eax), %eax - jmp *%eax +/* + * These symbols needed to be marked as .hidden to prevent the BFD linker from + * generating R_386_32 (rather than R_386_RELATIVE) relocations for them when + * the 32-bit compressed kernel is linked as PIE. This is no longer necessary, + * but it doesn't hurt to keep them .hidden. + */ + .hidden _bss + .hidden _ebss + .hidden _end -preferred_addr: -#endif + __HEAD +SYM_FUNC_START(startup_32) cld - /* - * Test KEEP_SEGMENTS flag to see if the bootloader is asking - * us to not reload segments - */ - testb $(1<<6), BP_loadflags(%esi) - jnz 1f - cli - movl $__BOOT_DS, %eax - movl %eax, %ds - movl %eax, %es - movl %eax, %fs - movl %eax, %gs - movl %eax, %ss -1: /* * Calculate the delta between where we were compiled to run @@ -101,31 +57,51 @@ preferred_addr: */ leal (BP_scratch+4)(%esi), %esp call 1f -1: popl %ebp - subl $1b, %ebp +1: popl %edx + addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %edx + + /* Load new GDT */ + leal gdt@GOTOFF(%edx), %eax + movl %eax, 2(%eax) + lgdt (%eax) + + /* Load segment registers with our descriptors */ + movl $__BOOT_DS, %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + movl %eax, %ss /* - * %ebp contains the address we are loaded at by the boot loader and %ebx - * contains the address where we should move the kernel image temporarily - * for safe in-place decompression. + * %edx contains the address we are loaded at by the boot loader (plus the + * offset to the GOT). The below code calculates %ebx to be the address where + * we should move the kernel image temporarily for safe in-place decompression + * (again, plus the offset to the GOT). + * + * %ebp is calculated to be the address that the kernel will be decompressed to. */ #ifdef CONFIG_RELOCATABLE - movl %ebp, %ebx + leal startup_32@GOTOFF(%edx), %ebx movl BP_kernel_alignment(%esi), %eax decl %eax addl %eax, %ebx notl %eax andl %eax, %ebx -#else - movl $LOAD_PHYSICAL_ADDR, %ebx + cmpl $LOAD_PHYSICAL_ADDR, %ebx + jae 1f #endif + movl $LOAD_PHYSICAL_ADDR, %ebx +1: + movl %ebx, %ebp // Save the output address for later /* Target address to relocate to for decompression */ - addl $z_extract_offset, %ebx + addl BP_init_size(%esi), %ebx + subl $_end@GOTOFF, %ebx /* Set up the stack */ - leal boot_stack_end(%ebx), %esp + leal boot_stack_end@GOTOFF(%ebx), %esp /* Zero EFLAGS */ pushl $0 @@ -136,8 +112,8 @@ preferred_addr: * where decompression in place becomes safe. */ pushl %esi - leal (_bss-4)(%ebp), %esi - leal (_bss-4)(%ebx), %edi + leal (_bss@GOTOFF-4)(%edx), %esi + leal (_bss@GOTOFF-4)(%ebx), %edi movl $(_bss - startup_32), %ecx shrl $2, %ecx std @@ -145,93 +121,68 @@ preferred_addr: cld popl %esi + /* + * The GDT may get overwritten either during the copy we just did or + * during extract_kernel below. To avoid any issues, repoint the GDTR + * to the new copy of the GDT. + */ + leal gdt@GOTOFF(%ebx), %eax + movl %eax, 2(%eax) + lgdt (%eax) + /* * Jump to the relocated address. */ - leal relocated(%ebx), %eax + leal .Lrelocated@GOTOFF(%ebx), %eax jmp *%eax -ENDPROC(startup_32) +SYM_FUNC_END(startup_32) .text -relocated: +SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) /* * Clear BSS (stack is currently empty) */ xorl %eax, %eax - leal _bss(%ebx), %edi - leal _ebss(%ebx), %ecx + leal _bss@GOTOFF(%ebx), %edi + leal _ebss@GOTOFF(%ebx), %ecx subl %edi, %ecx shrl $2, %ecx rep stosl /* - * Adjust our own GOT - */ - leal _got(%ebx), %edx - leal _egot(%ebx), %ecx -1: - cmpl %ecx, %edx - jae 2f - addl %ebx, (%edx) - addl $4, %edx - jmp 1b -2: - -/* - * Do the decompression, and jump to the new kernel.. - */ - leal z_extract_offset_negative(%ebx), %ebp - /* push arguments for decompress_kernel: */ - pushl %ebp /* output address */ - pushl $z_input_len /* input_len */ - leal input_data(%ebx), %eax - pushl %eax /* input_data */ - leal boot_heap(%ebx), %eax - pushl %eax /* heap area */ - pushl %esi /* real mode pointer */ - call decompress_kernel - addl $20, %esp - -#if CONFIG_RELOCATABLE -/* - * Find the address of the relocations. - */ - leal z_output_len(%ebp), %edi - -/* - * Calculate the delta between where vmlinux was compiled to run - * and where it was actually loaded. - */ - movl %ebp, %ebx - subl $LOAD_PHYSICAL_ADDR, %ebx - jz 2f /* Nothing to be done if loaded at compiled addr. */ -/* - * Process relocations. + * Do the extraction, and jump to the new kernel.. */ + /* push arguments for extract_kernel: */ -1: subl $4, %edi - movl (%edi), %ecx - testl %ecx, %ecx - jz 2f - addl %ebx, -__PAGE_OFFSET(%ebx, %ecx) - jmp 1b -2: -#endif + pushl %ebp /* output address */ + pushl %esi /* real mode pointer */ + call extract_kernel /* returns kernel entry point in %eax */ + addl $24, %esp /* - * Jump to the decompressed kernel. + * Jump to the extracted kernel. */ xorl %ebx, %ebx - jmp *%ebp + jmp *%eax +SYM_FUNC_END(.Lrelocated) + + .data + .balign 8 +SYM_DATA_START_LOCAL(gdt) + .word gdt_end - gdt - 1 + .long 0 + .word 0 + .quad 0x0000000000000000 /* Reserved */ + .quad 0x00cf9a000000ffff /* __KERNEL_CS */ + .quad 0x00cf92000000ffff /* __KERNEL_DS */ +SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end) /* * Stack and heap for uncompression */ .bss .balign 4 -boot_heap: - .fill BOOT_HEAP_SIZE, 1, 0 boot_stack: .fill BOOT_STACK_SIZE, 1, 0 boot_stack_end: |