diff options
| author |   Arvind Sankar <nivedita@alum.mit.edu> | 2020-01-07 14:44:34 -0500 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2020-01-23 11:58:43 +0100 |
| commit | 183ef7adf4ed638ac0fb0c3c9a71fc00e8512b61 (patch) | |
| tree | 2d58db55eedf738b53bfefafa5bfd64757c41ae8 /arch/x86/boot | |
| parent | x86/entry/64: Add instruction suffix to SYSRET (diff) | |
| download | linux-dev-183ef7adf4ed638ac0fb0c3c9a71fc00e8512b61.tar.xz linux-dev-183ef7adf4ed638ac0fb0c3c9a71fc00e8512b61.zip | |
x86/boot: Simplify calculation of output address
Condense the calculation of decompressed kernel start a little.
Committer notes:
before:
ebp = ebx - (init_size - _end)
after:
eax = (ebx + _end) - init_size
where in both ebx contains the temporary address the kernel is moved to
for in-place decompression.
The before and after difference in register state is %eax and %ebp
but that is immaterial because the compressed image is not built with
-mregparm, i.e., all arguments of the following extract_kernel() call
are passed on the stack.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200107194436.2166846-1-nivedita@alum.mit.edu
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_32.S | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index f2dfd6d083ef..1cc55c79d1d0 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -240,11 +240,9 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) /* push arguments for extract_kernel: */ pushl $z_output_len /* decompressed length, end of relocs */ - movl BP_init_size(%esi), %eax - subl $_end, %eax - movl %ebx, %ebp - subl %eax, %ebp - pushl %ebp /* output address */ + leal _end(%ebx), %eax + subl BP_init_size(%esi), %eax + pushl %eax /* output address */ pushl $z_input_len /* input_len */ leal input_data(%ebx), %eax |