AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

efi/arm: Fix absolute relocation detection for older toolchains

Browse Source 
When building the ARM kernel with CONFIG_EFI=y, the following build
error may occur when using a less recent version of binutils (2.23 or
older):

   STUBCPY drivers/firmware/efi/libstub/lib-sort.stub.o
 00000000 R_ARM_ABS32       sort
 00000004 R_ARM_ABS32       __ksymtab_strings
 drivers/firmware/efi/libstub/lib-sort.stub.o: absolute symbol references not allowed in the EFI stub

(and when building with debug symbols, the list above is much longer, and
contains all the internal references between the .debug sections and the
actual code)

This issue is caused by the fact that objcopy v2.23 or earlier does not
support wildcards in its -R and -j options, which means the following
line from the Makefile:

  STUBCOPY_FLAGS-y		:= -R .debug* -R *ksymtab* -R *kcrctab*

fails to take effect, leaving harmless absolute relocations in the binary
that are indistinguishable from relocations that may cause crashes at
runtime due to the fact that these relocations are resolved at link time
using the virtual address of the kernel, which is always different from
the address at which the EFI firmware loads and invokes the stub.

So, as a workaround, disable debug symbols explicitly when building the
stub for ARM, and strip the ksymtab and kcrctab symbols for the only
exported symbol we currently reuse in the stub, which is 'sort'.

Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1476805991-7160-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ard Biesheuvel 2016-10-18 16:53:11 +01:00 committed by Ingo Molnar
parent 6026ed2fe2
commit b0dddf6c14
1 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/firmware/efi/libstub/Makefile
View File

@ -11,7 +11,7 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
-mno-mmx -mno-sse
cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS))
cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \
cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) -g0 \
-fno-builtin -fpic -mno-single-pic-base
cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
@ -79,5 +79,6 @@ quiet_cmd_stubcopy = STUBCPY $@
# decompressor. So move our .data to .data.efistub, which is preserved
# explicitly by the decompressor linker script.
#
STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub
STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \
-R ___ksymtab+sort -R ___kcrctab+sort
STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS