linux/arch/x86/boot/compressed/mkpiggy.c
Arvind Sankar 3f086189cd 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
2020-08-14 12:52:35 +02:00

75 lines
1.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/* ----------------------------------------------------------------------- *
*
* Copyright (C) 2009 Intel Corporation. All rights reserved.
*
* H. Peter Anvin <hpa@linux.intel.com>
*
* -----------------------------------------------------------------------
*
* Outputs a small assembly wrapper with the appropriate symbols defined.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include <tools/le_byteshift.h>
int main(int argc, char *argv[])
{
uint32_t olen;
long ilen;
FILE *f = NULL;
int retval = 1;
if (argc < 2) {
fprintf(stderr, "Usage: %s compressed_file\n", argv[0]);
goto bail;
}
/* Get the information for the compressed kernel image first */
f = fopen(argv[1], "r");
if (!f) {
perror(argv[1]);
goto bail;
}
if (fseek(f, -4L, SEEK_END)) {
perror(argv[1]);
}
if (fread(&olen, sizeof(olen), 1, f) != 1) {
perror(argv[1]);
goto bail;
}
ilen = ftell(f);
olen = get_unaligned_le32(&olen);
printf(".section \".rodata..compressed\",\"a\",@progbits\n");
printf(".globl z_input_len\n");
printf("z_input_len = %lu\n", ilen);
printf(".globl z_output_len\n");
printf("z_output_len = %lu\n", (unsigned long)olen);
printf(".globl input_data, input_data_end\n");
printf("input_data:\n");
printf(".incbin \"%s\"\n", argv[1]);
printf("input_data_end:\n");
printf(".section \".rodata\",\"a\",@progbits\n");
printf(".globl input_len\n");
printf("input_len:\n\t.long %lu\n", ilen);
printf(".globl output_len\n");
printf("output_len:\n\t.long %lu\n", (unsigned long)olen);
retval = 0;
bail:
if (f)
fclose(f);
return retval;
}