diff options
| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-07-31 16:07:50 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-08-14 12:52:35 +0200 |
| commit | 3f086189cd3641d212949ff044d8e4486c93d55e (patch) | |
| tree | 8db21daf01187ddb9c6320ed326c17374372175b /arch/x86/boot/compressed/head_32.S | |
| parent | a2c4fc4d4e2c40b07534094810d915c7354d84a7 (diff) | |
| download | lwn-3f086189cd3641d212949ff044d8e4486c93d55e.tar.gz lwn-3f086189cd3641d212949ff044d8e4486c93d55e.zip | |
x86/boot: Remove run-time relocations from head_{32,64}.S
The BFD linker generates run-time relocations for z_input_len and
z_output_len, even though they are absolute symbols.
This is fixed for binutils-2.35 [1]. Work around this for earlier
versions by defining two variables input_len and output_len in addition
to the symbols, and use them via position-independent references.
This eliminates the last two run-time relocations in the head code and
allows us to drop the -z noreloc-overflow flag to the linker.
Move the -pie and --no-dynamic-linker LDFLAGS to LDFLAGS_vmlinux instead
of KBUILD_LDFLAGS. There shouldn't be anything else getting linked, but
this is the more logical location for these flags, and modversions might
call the linker if an EXPORT_SYMBOL is left over accidentally in one of
the decompressors.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=25754
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20200731230820.1742553-7-keescook@chromium.org
Diffstat (limited to 'arch/x86/boot/compressed/head_32.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_32.S | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 8c1a4f5610f5..659fad53ca82 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -178,18 +178,17 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) /* * Do the extraction, and jump to the new kernel.. */ - /* push arguments for extract_kernel: */ - pushl $z_output_len /* decompressed length, end of relocs */ + /* push arguments for extract_kernel: */ - pushl %ebp /* output address */ - - pushl $z_input_len /* input_len */ + pushl output_len@GOTOFF(%ebx) /* decompressed length, end of relocs */ + pushl %ebp /* output address */ + pushl input_len@GOTOFF(%ebx) /* input_len */ leal input_data@GOTOFF(%ebx), %eax - pushl %eax /* input_data */ + pushl %eax /* input_data */ leal boot_heap@GOTOFF(%ebx), %eax - pushl %eax /* heap area */ - pushl %esi /* real mode pointer */ - call extract_kernel /* returns kernel location in %eax */ + pushl %eax /* heap area */ + pushl %esi /* real mode pointer */ + call extract_kernel /* returns kernel location in %eax */ addl $24, %esp /* |