diff options
| -rw-r--r-- | CMakeLists.txt | 79 | ||||
| -rw-r--r-- | INSTALL | 8 | ||||
| -rw-r--r-- | configure.ac | 79 | ||||
| -rw-r--r-- | src/liblzma/check/crc32_fast.c | 48 | ||||
| -rw-r--r-- | src/liblzma/check/crc64_fast.c | 21 | ||||
| -rw-r--r-- | src/liblzma/check/crc_common.h | 9 | ||||
| -rw-r--r-- | src/liblzma/check/crc_x86_clmul.h | 11 |
7 files changed, 8 insertions, 247 deletions
diff --git a/CMakeLists.txt b/CMakeLists.txt index 9a4b69c5..7df02024 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -1099,85 +1099,6 @@ if(USE_WIN95_THREADS AND ENABLE_SMALL AND NOT HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR) endif() -# Check for __attribute__((__ifunc__())) support. -# Supported values for USE_ATTR_IFUNC: -# -# auto (default) - Detect ifunc support with a compile test. -# ON - Always enable ifunc. -# OFF - Disable ifunc usage. -set(USE_ATTR_IFUNC "auto" CACHE STRING "Use __attribute__((__ifunc__())).") - -set(SUPPORTED_USE_ATTR_IFUNC auto ON OFF) - -if(NOT USE_ATTR_IFUNC IN_LIST SUPPORTED_USE_ATTR_IFUNC) - message(FATAL_ERROR "'${USE_ATTR_IFUNC}' is not a supported value for" - "USE_ATTR_IFUNC") -endif() - -# When USE_ATTR_IFUNC is 'auto', allow the use of __attribute__((__ifunc__())) -# if compiler support is detected and we are building for GNU/Linux (glibc) -# or FreeBSD. uClibc and musl don't support ifunc in their dynamic linkers -# but some compilers still accept the attribute when compiling for these -# C libraries, which results in broken binaries. That's why we need to -# check which libc is being used. -if(USE_ATTR_IFUNC STREQUAL "auto") - cmake_push_check_state() - set(CMAKE_REQUIRED_FLAGS "-Werror") - - check_c_source_compiles(" - /* - * Force a compilation error when not using glibc on Linux - * or if we are not using FreeBSD. uClibc will define - * __GLIBC__ but does not support ifunc, so we must have - * an extra check to disable with uClibc. - */ - #if defined(__linux__) - # include <features.h> - # if !defined(__GLIBC__) || defined(__UCLIBC__) - compile error - # endif - #elif !defined(__FreeBSD__) - compile error - #endif - - static void func(void) { return; } - - /* - * The attribute __no_profile_instrument_function__ is - * needed with GCC to prevent improper instrumentation in - * the ifunc resolver. - */ - __attribute__((__no_profile_instrument_function__)) - static void (*resolve_func(void)) (void) { return func; } - void func_ifunc(void) - __attribute__((__ifunc__(\"resolve_func\"))); - int main(void) { return 0; } - /* - * 'clang -Wall' incorrectly warns that resolve_func is - * unused (-Wunused-function). Correct assembly output is - * still produced. This problem exists at least in Clang - * versions 4 to 17. The following silences the bogus warning: - */ - void make_clang_quiet(void); - void make_clang_quiet(void) { resolve_func()(); } - " - SYSTEM_SUPPORTS_IFUNC) - - cmake_pop_check_state() -endif() - -if(USE_ATTR_IFUNC STREQUAL "ON" OR SYSTEM_SUPPORTS_IFUNC) - tuklib_add_definitions(liblzma HAVE_FUNC_ATTRIBUTE_IFUNC) - - if(CMAKE_C_FLAGS MATCHES "-fsanitize=") - message(SEND_ERROR - "CMAKE_C_FLAGS or the environment variable CFLAGS " - "contains '-fsanitize=' which is incompatible " - "with ifunc. Use -DUSE_ATTR_IFUNC=OFF " - "as an argument to 'cmake' when using '-fsanitize'.") - endif() -endif() - # cpuid.h check_include_file(cpuid.h HAVE_CPUID_H) tuklib_add_definition_if(liblzma HAVE_CPUID_H) @@ -518,14 +518,6 @@ XZ Utils Installation calls any liblzma functions from more than one thread, something bad may happen. - --enable-ifunc - Use __attribute__((__ifunc__())) in liblzma. This is - enabled by default on GNU/Linux and FreeBSD. - - The ifunc attribute is incompatible with - -fsanitize=address. --disable-ifunc must be used - if any -fsanitize= option is specified in CFLAGS. - --enable-sandbox=METHOD There is limited sandboxing support in the xz and xzdec tools. If built with sandbox support, xz uses it diff --git a/configure.ac b/configure.ac index fb4f3d66..b6f9f8b7 100644 --- a/configure.ac +++ b/configure.ac @@ -893,85 +893,6 @@ if test "x$enable_small$enable_threads$have_func_attribute_constructor" \ __attribute__((__constructor__))]) fi -# __attribute__((__ifunc__())) can be used to choose between different -# implementations of the same function at runtime. This is slightly more -# efficient than using __attribute__((__constructor__)) and setting -# a function pointer. -AC_ARG_ENABLE([ifunc], [AS_HELP_STRING([--enable-ifunc], - [Use __attribute__((__ifunc__())). Enabled by default on - GNU/Linux (glibc) and FreeBSD.])], - [], [enable_ifunc=auto]) - -# When enable_ifunc is 'auto', allow the use of __attribute__((__ifunc__())) -# if compiler support is detected and we are building for GNU/Linux (glibc) -# or FreeBSD. uClibc and musl don't support ifunc in their dynamic linkers -# but some compilers still accept the attribute when compiling for these -# C libraries, which results in broken binaries. That's why we need to -# check which libc is being used. -if test "x$enable_ifunc" = xauto ; then - OLD_CFLAGS="$CFLAGS" - CFLAGS="$CFLAGS -Werror" - AC_MSG_CHECKING([if __attribute__((__ifunc__())) can be used]) - AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ - /* - * Force a compilation error when not using glibc on Linux - * or if we are not using FreeBSD. uClibc will define - * __GLIBC__ but does not support ifunc, so we must have - * an extra check to disable with uClibc. - */ - #if defined(__linux__) - # include <features.h> - # if !defined(__GLIBC__) || defined(__UCLIBC__) - compile error - # endif - #elif !defined(__FreeBSD__) - compile error - #endif - - static void func(void) { return; } - - /* - * The attribute __no_profile_instrument_function__ is - * needed with GCC to prevent improper instrumentation in - * the ifunc resolver. - */ - __attribute__((__no_profile_instrument_function__)) - static void (*resolve_func (void)) (void) { return func; } - void func_ifunc (void) - __attribute__((__ifunc__("resolve_func"))); - /* - * 'clang -Wall' incorrectly warns that resolve_func is - * unused (-Wunused-function). Correct assembly output is - * still produced. This problem exists at least in Clang - * versions 4 to 17. The following silences the bogus warning: - */ - void make_clang_quiet(void); - void make_clang_quiet(void) { resolve_func()(); } - ]])], [ - enable_ifunc=yes - ], [ - enable_ifunc=no - ]) - - AC_MSG_RESULT([$enable_ifunc]) - - CFLAGS="$OLD_CFLAGS" -fi - -if test "x$enable_ifunc" = xyes ; then - AC_DEFINE([HAVE_FUNC_ATTRIBUTE_IFUNC], [1], - [Define to 1 if __attribute__((__ifunc__())) - is supported for functions.]) - - # ifunc explicitly does not work with -fsanitize=address. - # If configured, it will result in a liblzma build that will fail - # when liblzma is loaded at runtime (when the ifunc resolver - # executes). - AS_CASE([$CFLAGS], [*-fsanitize=*], [AC_MSG_ERROR([ - CFLAGS contains '-fsanitize=' which is incompatible with ifunc. - Use --disable-ifunc when using '-fsanitize'.])]) -fi - ############################################################################### # Checks for library functions. diff --git a/src/liblzma/check/crc32_fast.c b/src/liblzma/check/crc32_fast.c index 079051f1..103da947 100644 --- a/src/liblzma/check/crc32_fast.c +++ b/src/liblzma/check/crc32_fast.c @@ -97,24 +97,14 @@ crc32_generic(const uint8_t *buf, size_t size, uint32_t crc) // If both the generic and arch-optimized implementations are built, then // the function to use is selected at runtime because the system running // the binary might not have the arch-specific instruction set extension(s) -// available. The three dispatch methods in order of priority: +// available. The dispatch methods in order of priority: // -// 1. Indirect function (ifunc). This method is slightly more efficient -// than the constructor method because it will change the entry in the -// Procedure Linkage Table (PLT) for the function either at load time or -// at the first call. This avoids having to call the function through a -// function pointer and will treat the function call like a regular call -// through the PLT. ifuncs are created by using -// __attribute__((__ifunc__("resolver"))) on a function which has no -// body. The "resolver" is the name of the function that chooses at -// runtime which implementation to use. -// -// 2. Constructor. This method uses __attribute__((__constructor__)) to +// 1. Constructor. This method uses __attribute__((__constructor__)) to // set crc32_func at load time. This avoids extra computation (and any // unlikely threading bugs) on the first call to lzma_crc32() to decide // which implementation should be used. // -// 3. First Call Resolution. On the very first call to lzma_crc32(), the +// 2. First Call Resolution. On the very first call to lzma_crc32(), the // call will be directed to crc32_dispatch() instead. This will set the // appropriate implementation function and will not be called again. // This method does not use any kind of locking but is safe because if @@ -124,22 +114,7 @@ crc32_generic(const uint8_t *buf, size_t size, uint32_t crc) typedef uint32_t (*crc32_func_type)( const uint8_t *buf, size_t size, uint32_t crc); -// Clang 16.0.0 and older has a bug where it marks the ifunc resolver -// function as unused since it is static and never used outside of -// __attribute__((__ifunc__())). -#if defined(CRC_USE_IFUNC) && defined(__clang__) -# pragma GCC diagnostic push -# pragma GCC diagnostic ignored "-Wunused-function" -#endif - -// This resolver is shared between all three dispatch methods. It serves as -// the ifunc resolver if ifunc is supported, otherwise it is called as a -// regular function by the constructor or first call resolution methods. -// The __no_profile_instrument_function__ attribute support is checked when -// determining if ifunc can be used, so it is safe to use here. -#ifdef CRC_USE_IFUNC -__attribute__((__no_profile_instrument_function__)) -#endif +// This resolver is shared between all dispatch methods. static crc32_func_type crc32_resolve(void) { @@ -147,11 +122,6 @@ crc32_resolve(void) ? &crc32_arch_optimized : &crc32_generic; } -#if defined(CRC_USE_IFUNC) && defined(__clang__) -# pragma GCC diagnostic pop -#endif - -#ifndef CRC_USE_IFUNC #ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR // Constructor method. @@ -176,8 +146,7 @@ crc32_set_func(void) static uint32_t crc32_dispatch(const uint8_t *buf, size_t size, uint32_t crc) { - // When __attribute__((__ifunc__(...))) and - // __attribute__((__constructor__)) isn't supported, set the + // When __attribute__((__constructor__)) isn't supported, set the // function pointer without any locking. If multiple threads run // the detection code in parallel, they will all end up setting // the pointer to the same value. This avoids the use of @@ -189,14 +158,8 @@ crc32_dispatch(const uint8_t *buf, size_t size, uint32_t crc) #endif #endif -#endif -#ifdef CRC_USE_IFUNC -extern LZMA_API(uint32_t) -lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc) - __attribute__((__ifunc__("crc32_resolve"))); -#else extern LZMA_API(uint32_t) lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc) { @@ -239,4 +202,3 @@ lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc) return crc32_generic(buf, size, crc); #endif } -#endif diff --git a/src/liblzma/check/crc64_fast.c b/src/liblzma/check/crc64_fast.c index 5728b45e..1a1aedcb 100644 --- a/src/liblzma/check/crc64_fast.c +++ b/src/liblzma/check/crc64_fast.c @@ -93,14 +93,6 @@ crc64_generic(const uint8_t *buf, size_t size, uint64_t crc) typedef uint64_t (*crc64_func_type)( const uint8_t *buf, size_t size, uint64_t crc); -#if defined(CRC_USE_IFUNC) && defined(__clang__) -# pragma GCC diagnostic push -# pragma GCC diagnostic ignored "-Wunused-function" -#endif - -#ifdef CRC_USE_IFUNC -__attribute__((__no_profile_instrument_function__)) -#endif static crc64_func_type crc64_resolve(void) { @@ -108,12 +100,6 @@ crc64_resolve(void) ? &crc64_arch_optimized : &crc64_generic; } -#if defined(CRC_USE_IFUNC) && defined(__clang__) -# pragma GCC diagnostic pop -#endif - -#ifndef CRC_USE_IFUNC - #ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR # define CRC64_SET_FUNC_ATTR __attribute__((__constructor__)) static crc64_func_type crc64_func; @@ -142,14 +128,8 @@ crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc) } #endif #endif -#endif -#ifdef CRC_USE_IFUNC -extern LZMA_API(uint64_t) -lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) - __attribute__((__ifunc__("crc64_resolve"))); -#else extern LZMA_API(uint64_t) lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) { @@ -174,4 +154,3 @@ lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) return crc64_generic(buf, size, crc); #endif } -#endif diff --git a/src/liblzma/check/crc_common.h b/src/liblzma/check/crc_common.h index 856665db..a700f03c 100644 --- a/src/liblzma/check/crc_common.h +++ b/src/liblzma/check/crc_common.h @@ -67,8 +67,6 @@ #undef CRC32_ARM64 #undef CRC64_ARM64_CLMUL -#undef CRC_USE_IFUNC - #undef CRC_USE_GENERIC_FOR_SMALL_INPUTS // ARM64 CRC32 instruction is only useful for CRC32. Currently, only @@ -109,9 +107,6 @@ # define CRC64_ARCH_OPTIMIZED 1 # define CRC_X86_CLMUL 1 -# ifdef HAVE_FUNC_ATTRIBUTE_IFUNC -# define CRC_USE_IFUNC 1 -# endif /* // The generic code is much faster with 1-8-byte inputs and // has similar performance up to 16 bytes at least in @@ -121,9 +116,7 @@ // for bigger inputs. It saves a little in code size since // the special cases for 0-16-byte inputs will be omitted // from the CLMUL code. -# ifndef CRC_USE_IFUNC -# define CRC_USE_GENERIC_FOR_SMALL_INPUTS 1 -# endif +# define CRC_USE_GENERIC_FOR_SMALL_INPUTS 1 */ # endif #endif diff --git a/src/liblzma/check/crc_x86_clmul.h b/src/liblzma/check/crc_x86_clmul.h index ae66ca9f..f1254ece 100644 --- a/src/liblzma/check/crc_x86_clmul.h +++ b/src/liblzma/check/crc_x86_clmul.h @@ -385,15 +385,8 @@ crc64_arch_optimized(const uint8_t *buf, size_t size, uint64_t crc) #endif // BUILDING_CRC64_CLMUL -// is_arch_extension_supported() must be inlined in this header file because -// the ifunc resolver function may not support calling a function in another -// translation unit. Depending on compiler-toolchain and flags, a call to -// a function defined in another translation unit could result in a -// reference to the PLT, which is unsafe to do in an ifunc resolver. The -// ifunc resolver runs very early when loading a shared library, so the PLT -// entries may not be setup at that time. Inlining this function duplicates -// the function body in crc32_resolve() and crc64_resolve(), but this is -// acceptable because the function results in very few instructions. +// Inlining this function duplicates the function body in crc32_resolve() and +// crc64_resolve(), but this is acceptable because this is a tiny function. static inline bool is_arch_extension_supported(void) { |