From 5fbf2e09921723cfdea75e83c1fac2080f0ad564 Mon Sep 17 00:00:00 2001 From: David 'Digit' Turner Date: Mon, 23 Jan 2012 15:15:30 +0100 Subject: [PATCH] libc: Define new symbol visibility macros This patch defines a few new macros that can be used to control the visibility of symbols exported by the C library: - ENTRY_PRIVATE() can be used in assembly sources to indicate that an assembler function should have "hidden" visibility, i.e. will never be exported by the C library's shared library. This is the equivalent of using __LIBC_HIDDEN__ for a C function, but ENTRY_PRIVATE() works like ENTRY(), and must be used with END() to tag the end of the function. - __LIBC_ABI_PUBLIC__ can be used to tag a C functions as being part of the C library's public ABI. This is important for a few functions that must be exposed by the NDK to maintain binary compatibility. Once a symbol has been tagged with this macro, it shall *never* be removed from the library, even if it becomes directly unused due to implementation changes (e.g. __is_threaded). - __LIBC_ABI_PRIVATE__ can be used for C functions that should always be exported by the C library because they are used by other libraries in the platform, but should not be exposed by the NDK. It is possible to remove such symbols from the implementation if all callers are also modified. + Add missing END() assembly macro for x86 Change-Id: Ia96236ea0dbec41d57bea634b39d246b30e5e234 --- libc/arch-arm/include/machine/asm.h | 6 ++++++ libc/arch-x86/include/machine/asm.h | 10 ++++++++++ libc/include/sys/cdefs_elf.h | 15 +++++++++++++++ 3 files changed, 31 insertions(+) diff --git a/libc/arch-arm/include/machine/asm.h b/libc/arch-arm/include/machine/asm.h index 7b8f05330..047e54d17 100644 --- a/libc/arch-arm/include/machine/asm.h +++ b/libc/arch-arm/include/machine/asm.h @@ -97,6 +97,12 @@ #define ASENTRY_NP(y) _ENTRY(_ASM_LABEL(y)) #define ASEND(y) _END(_ASM_LABEL(y)) +#ifdef __ELF__ +#define ENTRY_PRIVATE(y) ENTRY(y); .hidden _C_LABEL(y) +#else +#define ENTRY_PRIVATE(y) ENTRY(y) +#endif + #define ASMSTR .asciz #if defined(__ELF__) && defined(PIC) diff --git a/libc/arch-x86/include/machine/asm.h b/libc/arch-x86/include/machine/asm.h index 7a23060a9..49d3ea8d1 100644 --- a/libc/arch-x86/include/machine/asm.h +++ b/libc/arch-x86/include/machine/asm.h @@ -103,6 +103,12 @@ #define _ENTRY(x) \ .text; _ALIGN_TEXT; .globl x; .type x,@function; x: +#define _ASM_SIZE(x) .size x, .-x; + +#define _END(x) \ + .fnend; \ + _ASM_SIZE(x) + #ifdef GPROF # define _PROF_PROLOGUE \ pushl %ebp; movl %esp,%ebp; call PIC_PLT(mcount); popl %ebp @@ -112,8 +118,12 @@ #define ENTRY(y) _ENTRY(_C_LABEL(y)); _PROF_PROLOGUE #define NENTRY(y) _ENTRY(_C_LABEL(y)) +#define END(y) _END(_C_LABEL(y)) #define ASENTRY(y) _ENTRY(_ASM_LABEL(y)); _PROF_PROLOGUE +#define ENTRY_PRIVATE(y) ENTRY(y); .hidden _C_LABEL(y) + + #define ALTENTRY(name) .globl _C_LABEL(name); _C_LABEL(name): #define ASMSTR .asciz diff --git a/libc/include/sys/cdefs_elf.h b/libc/include/sys/cdefs_elf.h index 1e5747010..0887fa57b 100644 --- a/libc/include/sys/cdefs_elf.h +++ b/libc/include/sys/cdefs_elf.h @@ -96,9 +96,24 @@ #endif /* GCC visibility helper macro */ +/* This must be used to tag non-static functions that are private, i.e. + * never exposed by the shared library. */ #define __LIBC_HIDDEN__ \ __attribute__ ((visibility ("hidden"))) +/* This must be used to tag non-static functions that are public, i.e. + * exposed by the shared library, and part of the stable NDK ABI */ +#define __LIBC_ABI_PUBLIC__ \ + __attribute__ ((visibility ("default"))) + +/* This must be used to tag non-static functions that must be exported + * by the shared library, but whose implementation is private to the + * platform. For now this is equivalent to __LIBC_ABI_PUBLIC__, but we + * may want to change this later. + */ +#define __LIBC_ABI_PRIVATE__ \ + __attribute__ ((visibility ("default"))) + #define __IDSTRING(_n,_s) __SECTIONSTRING(.ident,_s) #define __RCSID(_s) __IDSTRING(rcsid,_s)