diff options
| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-02-11 12:33:33 -0500 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-02-12 11:15:31 +0100 |
| commit | a86255fe5258714e1f7c1bdfe95f08e4d098d450 (patch) | |
| tree | 3d8cf59e919a85f754a8a7a6da7dfdab4fd7b257 /arch/x86/boot | |
| parent | 48bfdb9deffdc6b683feb25e15f4f26aac503501 (diff) | |
x86/boot/compressed/64: Use 32-bit (zero-extended) MOV for z_output_len
z_output_len is the size of the decompressed payload (i.e. vmlinux +
vmlinux.relocs) and is generated as an unsigned 32-bit quantity by
mkpiggy.c.
The current
movq $z_output_len, %r9
instruction generates a sign-extended move to %r9. Using
movl $z_output_len, %r9d
will instead zero-extend into %r9, which is appropriate for an unsigned
32-bit quantity. This is also what is already done for z_input_len, the
size of the compressed payload.
[ bp:
Also, z_output_len cannot be a 64-bit quantity because it participates
in:
init_size: .long INIT_SIZE # kernel initialization size
through INIT_SIZE which is a 32-bit quantity determined by the .long
directive (vs .quad for 64-bit). Furthermore, if it really must be a
64-bit quantity, then the insn must be MOVABS which can accommodate a
64-bit immediate and which the toolchain does not generate automatically.
]
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200211173333.1722739-1-nivedita@alum.mit.edu
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index d1220de1de52..68f31c48d6c2 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -482,7 +482,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) leaq input_data(%rip), %rdx /* input_data */ movl $z_input_len, %ecx /* input_len */ movq %rbp, %r8 /* output target address */ - movq $z_output_len, %r9 /* decompressed length, end of relocs */ + movl $z_output_len, %r9d /* decompressed length, end of relocs */ call extract_kernel /* returns kernel location in %rax */ popq %rsi |