diff options
| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-03-08 09:08:46 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-08 09:58:19 +0100 |
| commit | 8ef44be393113dca5cece65bc142ebb8ef013af0 (patch) | |
| tree | f1a8a573fc98cf46ce7ff20d4b4f8c3e7751c99e /arch/x86/boot | |
| parent | f3fa0efce2e765f24356b70bd0786f290d84328c (diff) | |
x86/boot/compressed/32: Save the output address instead of recalculating it
In preparation for being able to decompress into a buffer starting at a
different address than startup_32, save the calculated output address
instead of recalculating it later.
We now keep track of three addresses:
%edx: startup_32 as we were loaded by bootloader
%ebx: new location of compressed kernel
%ebp: start of decompression buffer
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200303221205.4048668-2-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-16-ardb@kernel.org
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_32.S | 25 |
1 files changed, 12 insertions, 13 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 46bbe7ab4adf..894182500606 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -75,11 +75,11 @@ SYM_FUNC_START(startup_32) */ leal (BP_scratch+4)(%esi), %esp call 1f -1: popl %ebp - subl $1b, %ebp +1: popl %edx + subl $1b, %edx /* Load new GDT */ - leal gdt(%ebp), %eax + leal gdt(%edx), %eax movl %eax, 2(%eax) lgdt (%eax) @@ -92,13 +92,14 @@ SYM_FUNC_START(startup_32) movl %eax, %ss /* - * %ebp contains the address we are loaded at by the boot loader and %ebx + * %edx 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. + * for safe in-place decompression. %ebp contains the address that the kernel + * will be decompressed to. */ #ifdef CONFIG_RELOCATABLE - movl %ebp, %ebx + movl %edx, %ebx movl BP_kernel_alignment(%esi), %eax decl %eax addl %eax, %ebx @@ -110,10 +111,10 @@ SYM_FUNC_START(startup_32) movl $LOAD_PHYSICAL_ADDR, %ebx 1: + movl %ebx, %ebp // Save the output address for later /* Target address to relocate to for decompression */ - movl BP_init_size(%esi), %eax - subl $_end, %eax - addl %eax, %ebx + addl BP_init_size(%esi), %ebx + subl $_end, %ebx /* Set up the stack */ leal boot_stack_end(%ebx), %esp @@ -127,7 +128,7 @@ SYM_FUNC_START(startup_32) * where decompression in place becomes safe. */ pushl %esi - leal (_bss-4)(%ebp), %esi + leal (_bss-4)(%edx), %esi leal (_bss-4)(%ebx), %edi movl $(_bss - startup_32), %ecx shrl $2, %ecx @@ -196,9 +197,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) /* push arguments for extract_kernel: */ pushl $z_output_len /* decompressed length, end of relocs */ - leal _end(%ebx), %eax - subl BP_init_size(%esi), %eax - pushl %eax /* output address */ + pushl %ebp /* output address */ pushl $z_input_len /* input_len */ leal input_data(%ebx), %eax |