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e0891269a8
Currently aliasing an asm function requires adding START and END annotations for each name, as per Documentation/asm-annotations.rst: SYM_FUNC_START_ALIAS(__memset) SYM_FUNC_START(memset) ... asm insns ... SYM_FUNC_END(memset) SYM_FUNC_END_ALIAS(__memset) This is more painful than necessary to maintain, especially where a function has many aliases, some of which we may wish to define conditionally. For example, arm64's memcpy/memmove implementation (which uses some arch-specific SYM_*() helpers) has: SYM_FUNC_START_ALIAS(__memmove) SYM_FUNC_START_ALIAS_WEAK_PI(memmove) SYM_FUNC_START_ALIAS(__memcpy) SYM_FUNC_START_WEAK_PI(memcpy) ... asm insns ... SYM_FUNC_END_PI(memcpy) EXPORT_SYMBOL(memcpy) SYM_FUNC_END_ALIAS(__memcpy) EXPORT_SYMBOL(__memcpy) SYM_FUNC_END_ALIAS_PI(memmove) EXPORT_SYMBOL(memmove) SYM_FUNC_END_ALIAS(__memmove) EXPORT_SYMBOL(__memmove) SYM_FUNC_START(name) It would be much nicer if we could define the aliases *after* the standard function definition. This would avoid the need to specify each symbol name twice, and would make it easier to spot the canonical function definition. This patch adds new macros to allow us to do so, which allows the above example to be rewritten more succinctly as: SYM_FUNC_START(__pi_memcpy) ... asm insns ... SYM_FUNC_END(__pi_memcpy) SYM_FUNC_ALIAS(__memcpy, __pi_memcpy) EXPORT_SYMBOL(__memcpy) SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy) EXPORT_SYMBOL(memcpy) SYM_FUNC_ALIAS(__pi_memmove, __pi_memcpy) SYM_FUNC_ALIAS(__memmove, __pi_memmove) EXPORT_SYMBOL(__memmove) SYM_FUNC_ALIAS_WEAK(memmove, __memmove) EXPORT_SYMBOL(memmove) The reduction in duplication will also make it possible to replace some uses of WEAK with more accurate Kconfig guards, e.g. #ifndef CONFIG_KASAN SYM_FUNC_ALIAS(memmove, __memmove) EXPORT_SYMBOL(memmove) #endif ... which should make it easier to ensure that symbols are neither used nor overidden unexpectedly. The existing SYM_FUNC_START_ALIAS() and SYM_FUNC_START_LOCAL_ALIAS() are marked as deprecated, and will be removed once existing users are moved over to the new scheme. The tools/perf/ copy of linkage.h is updated to match. A subsequent patch will depend upon this when updating the x86 asm annotations. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Mark Brown <broonie@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220216162229.1076788-2-mark.rutland@arm.com Signed-off-by: Will Deacon <will@kernel.org> |
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| arch | ||
| bench | ||
| dlfilters | ||
| Documentation | ||
| examples/bpf | ||
| include | ||
| jvmti | ||
| pmu-events | ||
| python | ||
| scripts | ||
| tests | ||
| trace | ||
| ui | ||
| util | ||
| .gitignore | ||
| Build | ||
| builtin-annotate.c | ||
| builtin-bench.c | ||
| builtin-buildid-cache.c | ||
| builtin-buildid-list.c | ||
| builtin-c2c.c | ||
| builtin-config.c | ||
| builtin-daemon.c | ||
| builtin-data.c | ||
| builtin-diff.c | ||
| builtin-evlist.c | ||
| builtin-ftrace.c | ||
| builtin-help.c | ||
| builtin-inject.c | ||
| builtin-kallsyms.c | ||
| builtin-kmem.c | ||
| builtin-kvm.c | ||
| builtin-list.c | ||
| builtin-lock.c | ||
| builtin-mem.c | ||
| builtin-probe.c | ||
| builtin-record.c | ||
| builtin-report.c | ||
| builtin-sched.c | ||
| builtin-script.c | ||
| builtin-stat.c | ||
| builtin-timechart.c | ||
| builtin-top.c | ||
| builtin-trace.c | ||
| builtin-version.c | ||
| builtin.h | ||
| check-headers.sh | ||
| command-list.txt | ||
| CREDITS | ||
| design.txt | ||
| Makefile | ||
| Makefile.config | ||
| Makefile.perf | ||
| MANIFEST | ||
| perf-archive.sh | ||
| perf-completion.sh | ||
| perf-iostat.sh | ||
| perf-read-vdso.c | ||
| perf-sys.h | ||
| perf-with-kcore.sh | ||
| perf.c | ||
| perf.h | ||