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bdbc0c7a07
Some compilers may put a subset of generated functions into '.text.*' ELF sections and the linker may leverage this division to optimize ELF layout. Unfortunately, the recently introduced HYPCOPY command assumes that all executable code (with the exception of specialized sections such as '.hyp.idmap.text') is in the '.text' section. If this assumption is broken, code in '.text.*' will be merged into kernel proper '.text' instead of the '.hyp.text' that is mapped in EL2. To ensure that this cannot happen, insert an OBJDUMP assertion into HYPCOPY. The command dumps a list of ELF sections in the input object file and greps for '.text.'. If found, compilation fails. Tested with both binutils' and LLVM's objdump (the output format is different). GCC offers '-fno-reorder-functions' to disable this behaviour. Select the flag if it is available. From inspection of GCC source (latest Git in July 2020), this flag does force all code into '.text'. By default, GCC uses profile data, heuristics and attributes to select a subsection. LLVM/Clang currently does not have a similar optimization pass. It can place static constructors into '.text.startup' and it's optimizer can be provided with profile data to reorder hot/cold functions. Neither of these is applicable to nVHE hyp code. If this changes in the future, the OBJDUMP assertion should alert users to the problem. Signed-off-by: David Brazdil <dbrazdil@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20200730132519.48787-1-dbrazdil@google.com |
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| include | ||
| kernel | ||
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| lib | ||
| mm | ||
| net | ||
| xen | ||
| Kbuild | ||
| Kconfig | ||
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| Kconfig.platforms | ||
| Makefile | ||