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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 21:54:06 +08:00
linux-next/arch/x86
Arvind Sankar 5214028dd8 x86/boot: Correct relocation destination on old linkers
For the 32-bit kernel, as described in

  6d92bc9d48 ("x86/build: Build compressed x86 kernels as PIE"),

pre-2.26 binutils generates R_386_32 relocations in PIE mode. Since the
startup code does not perform relocation, any reloc entry with R_386_32
will remain as 0 in the executing code.

Commit

  974f221c84 ("x86/boot: Move compressed kernel to the end of the
                 decompression buffer")

added a new symbol _end but did not mark it hidden, which doesn't give
the correct offset on older linkers. This causes the compressed kernel
to be copied beyond the end of the decompression buffer, rather than
flush against it. This region of memory may be reserved or already
allocated for other purposes by the bootloader.

Mark _end as hidden to fix. This changes the relocation from R_386_32 to
R_386_RELATIVE even on the pre-2.26 binutils.

For 64-bit, this is not strictly necessary, as the 64-bit kernel is only
built as PIE if the linker supports -z noreloc-overflow, which implies
binutils-2.27+, but for consistency, mark _end as hidden here too.

The below illustrates the before/after impact of the patch using
binutils-2.25 and gcc-4.6.4 (locally compiled from source) and QEMU.

  Disassembly before patch:
    48:   8b 86 60 02 00 00       mov    0x260(%esi),%eax
    4e:   2d 00 00 00 00          sub    $0x0,%eax
                          4f: R_386_32    _end
  Disassembly after patch:
    48:   8b 86 60 02 00 00       mov    0x260(%esi),%eax
    4e:   2d 00 f0 76 00          sub    $0x76f000,%eax
                          4f: R_386_RELATIVE      *ABS*

Dump from extract_kernel before patch:
	early console in extract_kernel
	input_data: 0x0207c098 <--- this is at output + init_size
	input_len: 0x0074fef1
	output: 0x01000000
	output_len: 0x00fa63d0
	kernel_total_size: 0x0107c000
	needed_size: 0x0107c000

Dump from extract_kernel after patch:
	early console in extract_kernel
	input_data: 0x0190d098 <--- this is at output + init_size - _end
	input_len: 0x0074fef1
	output: 0x01000000
	output_len: 0x00fa63d0
	kernel_total_size: 0x0107c000
	needed_size: 0x0107c000

Fixes: 974f221c84 ("x86/boot: Move compressed kernel to the end of the decompression buffer")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200207214926.3564079-1-nivedita@alum.mit.edu
2020-05-19 14:11:22 +02:00
..
boot x86/boot: Correct relocation destination on old linkers 2020-05-19 14:11:22 +02:00
configs compiler: remove CONFIG_OPTIMIZE_INLINING entirely 2020-04-07 10:43:42 -07:00
crypto x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
entry sparc,x86: vdso: remove meaningless undefining CONFIG_OPTIMIZE_INLINING 2020-04-07 10:43:42 -07:00
events perf/x86/cstate: Add Jasper Lake CPU support 2020-04-22 21:43:12 +02:00
hyperv x86/Hyper-V: Report crash data in die() when panic_on_oops is set 2020-04-11 17:19:07 +01:00
ia32 Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-03-31 11:04:05 -07:00
include Kbuild fixes for v5.7 2020-04-24 10:39:32 -07:00
kernel x86/tboot: Mark tboot static 2020-04-28 11:05:44 +02:00
kvm KVM: s390: Fix for 5.7 and maintainer update 2020-04-21 09:37:13 -04:00
lib SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
math-emu Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 10:42:40 -08:00
mm mm/memory_hotplug: add pgprot_t to mhp_params 2020-04-10 15:36:21 -07:00
net bpf, x86_32: Fix logic error in BPF_LDX zero-extension 2020-04-24 17:23:01 -07:00
oprofile x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
pci pci-v5.6-changes 2020-01-31 14:48:54 -08:00
platform efi/x86: Don't remap text<->rodata gap read-only for mixed mode 2020-04-14 08:32:17 +02:00
power x86/kernel: Convert to new CPU match macros 2020-03-24 21:28:26 +01:00
purgatory Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 10:42:40 -08:00
ras
realmode SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
tools .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
um mm/vma: define a default value for VM_DATA_DEFAULT_FLAGS 2020-04-10 15:36:21 -07:00
video
xen xen: branch for v5.7-rc1b 2020-04-10 17:20:06 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
Kbuild
Kconfig mm/userfaultfd: disable userfaultfd-wp on x86_32 2020-04-21 11:11:55 -07:00
Kconfig.assembler x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
Kconfig.cpu x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs 2020-01-13 18:02:53 +01:00
Kconfig.debug x86: mm: convert dump_pagetables to use walk_page_range 2020-02-04 03:05:25 +00:00
Makefile x86: probe assembler capabilities via kconfig instead of makefile 2020-04-09 00:01:59 +09:00
Makefile_32.cpu x86/math-emu: Limit MATH_EMULATION to 486SX compatibles 2019-10-03 10:51:17 +02:00
Makefile.um