Commit 0c314cda authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Thomas Gleixner
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arm64: vdso: Work around invalid absolute relocations from GCC 



All vDSO code needs to be completely position independent.  Symbol
references are marked as hidden so the compiler emits PC-relative
relocations.

However GCC emits absolute relocations for symbol-relative references with
an offset >= 64KiB. After recent refactorings in the vDSO code this is the
case in __arch_get_vdso_u_timens_data() with a page size of 64KiB.

Work around the issue by preventing the optimizer from seeing the offsets.

Fixes: 83a2a6b8 ("vdso/gettimeofday: Prepare do_hres_timens() for introduction of struct vdso_clock")
Reported-by: default avatarJan Stancek <jstancek@redhat.com>
Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/all/20250430-vdso-absolute-reloc-v2-1-5efcc3bc4b26@linutronix.de
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120002
Closes: https://lore.kernel.org/lkml/aApGPAoctq_eoE2g@t14ultra/
parent b71f9804

arch/arm64/include/asm/vdso/gettimeofday.h

+13 −0
Original line number Diff line number Diff line
@@ -99,6 +99,19 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode, 
	return res;

}



#if IS_ENABLED(CONFIG_CC_IS_GCC) && IS_ENABLED(CONFIG_PAGE_SIZE_64KB)

static __always_inline const struct vdso_time_data *__arch_get_vdso_u_time_data(void)

{

	const struct vdso_time_data *ret = &vdso_u_time_data;



	/* Work around invalid absolute relocations */

	OPTIMIZER_HIDE_VAR(ret);



	return ret;

}

#define __arch_get_vdso_u_time_data __arch_get_vdso_u_time_data

#endif /* IS_ENABLED(CONFIG_CC_IS_GCC) && IS_ENABLED(CONFIG_PAGE_SIZE_64KB) */



#endif /* !__ASSEMBLY__ */



#endif /* __ASM_VDSO_GETTIMEOFDAY_H */