lib/string.c: Use freestanding environment
gcc can transform the loop in a naive implementation of memset/memcpy etc into a call to the function itself. This optimization is enabled by -ftree-loop-distribute-patterns. This has been the case for a while, but gcc-10.x enables this option at -O2 rather than -O3 as in previous versions. Add -ffreestanding, which implicitly disables this optimization with gcc. It is unclear whether clang performs such optimizations, but hopefully it will also not do so in a freestanding environment. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56888 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -15,11 +15,16 @@ KCOV_INSTRUMENT_debugobjects.o := n
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KCOV_INSTRUMENT_dynamic_debug.o := n
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KCOV_INSTRUMENT_dynamic_debug.o := n
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KCOV_INSTRUMENT_fault-inject.o := n
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KCOV_INSTRUMENT_fault-inject.o := n
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# string.o implements standard library functions like memset/memcpy etc.
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# Use -ffreestanding to ensure that the compiler does not try to "optimize"
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# them into calls to themselves.
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CFLAGS_string.o := -ffreestanding
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# Early boot use of cmdline, don't instrument it
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# Early boot use of cmdline, don't instrument it
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ifdef CONFIG_AMD_MEM_ENCRYPT
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ifdef CONFIG_AMD_MEM_ENCRYPT
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KASAN_SANITIZE_string.o := n
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KASAN_SANITIZE_string.o := n
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CFLAGS_string.o := -fno-stack-protector
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CFLAGS_string.o += -fno-stack-protector
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endif
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endif
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# Used by KCSAN while enabled, avoid recursion.
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# Used by KCSAN while enabled, avoid recursion.
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