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authorArvind Sankar <nivedita@alum.mit.edu>2020-02-11 12:33:33 -0500
committerBorislav Petkov <bp@suse.de>2020-02-12 11:15:31 +0100
commita86255fe5258714e1f7c1bdfe95f08e4d098d450 (patch)
tree3d8cf59e919a85f754a8a7a6da7dfdab4fd7b257 /arch/x86/boot
parent48bfdb9deffdc6b683feb25e15f4f26aac503501 (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.S2
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