linux/arch/arm64/include/asm/module.lds.h
Mark Rutland ea3752ba96 arm64: module: mandate MODULE_PLTS
Contemporary kernels and modules can be relatively large, especially
when common debug options are enabled. Using GCC 12.1.0, a v6.3-rc7
defconfig kernel is ~38M, and with PROVE_LOCKING + KASAN_INLINE enabled
this expands to ~117M. Shanker reports [1] that the NVIDIA GPU driver
alone can consume 110M of module space in some configurations.

Both KASLR and ARM64_ERRATUM_843419 select MODULE_PLTS, so anyone
wanting a kernel to have KASLR or run on Cortex-A53 will have
MODULE_PLTS selected. This is the case in defconfig and distribution
kernels (e.g. Debian, Android, etc).

Practically speaking, this means we're very likely to need MODULE_PLTS
and while it's almost guaranteed that MODULE_PLTS will be selected, it
is possible to disable support, and we have to maintain some awkward
special cases for such unusual configurations.

This patch removes the MODULE_PLTS config option, with the support code
always enabled if MODULES is selected. This results in a slight
simplification, and will allow for further improvement in subsequent
patches.

For any config which currently selects MODULE_PLTS, there will be no
functional change as a result of this patch.

[1] https://lore.kernel.org/linux-arm-kernel/159ceeab-09af-3174-5058-445bc8dcf85b@nvidia.com/

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Shanker Donthineni <sdonthineni@nvidia.com>
Cc: Will Deacon <will@kernel.org>
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com>
Link: https://lore.kernel.org/r/20230530110328.2213762-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-06-06 17:39:05 +01:00

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795 B
C

SECTIONS {
.plt 0 : { BYTE(0) }
.init.plt 0 : { BYTE(0) }
.text.ftrace_trampoline 0 : { BYTE(0) }
#ifdef CONFIG_KASAN_SW_TAGS
/*
* Outlined checks go into comdat-deduplicated sections named .text.hot.
* Because they are in comdats they are not combined by the linker and
* we otherwise end up with multiple sections with the same .text.hot
* name in the .ko file. The kernel module loader warns if it sees
* multiple sections with the same name so we use this sections
* directive to force them into a single section and silence the
* warning.
*/
.text.hot : { *(.text.hot) }
#endif
#ifdef CONFIG_UNWIND_TABLES
/*
* Currently, we only use unwind info at module load time, so we can
* put it into the .init allocation.
*/
.init.eh_frame : { *(.eh_frame) }
#endif
}