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OpenCloudOS-Kernel/arch/arm/kernel/module.lds

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ARM: 8220/1: allow modules outside of bl range Loading modules far away from the kernel in memory is problematic because the 'bl' instruction only has limited reach, and modules are not built with PLTs. Instead of using the -mlong-calls option (which affects all compiler emitted bl instructions, but not the ones in assembler), this patch allocates some additional space at module load time, and populates it with PLT like veneers when encountering relocations that are out of range. This should work with all relocations against symbols exported by the kernel, including those resulting from GCC generated implicit function calls for ftrace etc. The module memory size increases by about 5% on average, regardless of whether any PLT entries were actually needed. However, due to the page based rounding that occurs when allocating module memory, the average memory footprint increase is negligible. Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-24 23:54:35 +08:00
SECTIONS {
ARM: kernel: merge core and init PLTs The PLT code uses a separate .init.plt section to allocate PLT entries for jump and call instructions in __init code. However, even for fairly sizable modules like mac80211.ko, we only end up with a couple of PLT entries in the .init section, and so we can simplify the code significantly by emitting all PLT entries into the same section. Tested-by: Jongsung Kim <neidhard.kim@lge.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
2016-08-16 23:21:02 +08:00
.plt : { BYTE(0) }
ARM: 8220/1: allow modules outside of bl range Loading modules far away from the kernel in memory is problematic because the 'bl' instruction only has limited reach, and modules are not built with PLTs. Instead of using the -mlong-calls option (which affects all compiler emitted bl instructions, but not the ones in assembler), this patch allocates some additional space at module load time, and populates it with PLT like veneers when encountering relocations that are out of range. This should work with all relocations against symbols exported by the kernel, including those resulting from GCC generated implicit function calls for ftrace etc. The module memory size increases by about 5% on average, regardless of whether any PLT entries were actually needed. However, due to the page based rounding that occurs when allocating module memory, the average memory footprint increase is negligible. Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-24 23:54:35 +08:00
}