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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3789c122d0
Our out-of-line atomics are built with a special calling convention, preventing pointless stack spilling, and allowing us to patch call sites with ARMv8.1 atomic instructions. Instrumentation inserted by the compiler may result in calls to functions not following this special calling convention, resulting in registers being unexpectedly clobbered, and various problems resulting from this. For example, if a kernel is built with KCOV and ARM64_LSE_ATOMICS, the compiler inserts calls to __sanitizer_cov_trace_pc in the prologues of the atomic functions. This has been observed to result in spurious cmpxchg failures, leading to a hang early on in the boot process. This patch avoids such issues by preventing instrumentation of our out-of-line atomics. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
28 lines
1.3 KiB
Makefile
28 lines
1.3 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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lib-y := bitops.o clear_user.o delay.o copy_from_user.o \
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copy_to_user.o copy_in_user.o copy_page.o \
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clear_page.o memchr.o memcpy.o memmove.o memset.o \
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memcmp.o strcmp.o strncmp.o strlen.o strnlen.o \
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strchr.o strrchr.o tishift.o
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# Tell the compiler to treat all general purpose registers (with the
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# exception of the IP registers, which are already handled by the caller
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# in case of a PLT) as callee-saved, which allows for efficient runtime
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# patching of the bl instruction in the caller with an atomic instruction
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# when supported by the CPU. Result and argument registers are handled
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# correctly, based on the function prototype.
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lib-$(CONFIG_ARM64_LSE_ATOMICS) += atomic_ll_sc.o
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CFLAGS_atomic_ll_sc.o := -fcall-used-x0 -ffixed-x1 -ffixed-x2 \
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-ffixed-x3 -ffixed-x4 -ffixed-x5 -ffixed-x6 \
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-ffixed-x7 -fcall-saved-x8 -fcall-saved-x9 \
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-fcall-saved-x10 -fcall-saved-x11 -fcall-saved-x12 \
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-fcall-saved-x13 -fcall-saved-x14 -fcall-saved-x15 \
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-fcall-saved-x18 -fomit-frame-pointer
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CFLAGS_REMOVE_atomic_ll_sc.o := -pg
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GCOV_PROFILE_atomic_ll_sc.o := n
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KASAN_SANITIZE_atomic_ll_sc.o := n
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KCOV_INSTRUMENT_atomic_ll_sc.o := n
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UBSAN_SANITIZE_atomic_ll_sc.o := n
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lib-$(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) += uaccess_flushcache.o
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