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>
4 lines
77 B
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4 lines
77 B
Text
SECTIONS {
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.core.plt : { BYTE(0) }
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.init.plt : { BYTE(0) }
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}
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