From 2ef427168818ce04b03cecb7b739f9db0156e3e4 Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Thu, 3 Jan 2019 15:51:37 +0100 Subject: Only build libm with -fno-math-errno (bug 24024) Commit 1294b1892e ("Add support for sqrt asm redirects") added the -fno-math-errno flag to build most of the glibc in order to enable GCC to inline math functions. Due to GCC bug #88576, saving and restoring errno around calls to malloc are optimized-out. In turn this causes strerror to set errno to ENOMEM if it get passed an invalid error number and if malloc sets errno to ENOMEM (which might happen even if it succeeds). This is not allowed by POSIX. This patch changes the build flags, building only libm with -fno-math-errno and all the remaining code with -fno-math-errno. This should be safe as libm doesn't contain any code saving and restoring errno around malloc. This patch can probably be reverted once the GCC bug is fixed and available in stable releases. Tested on x86-64, no regression in the testsuite. Changelog: [BZ #24024] * Makeconfig: Build libm with -fno-math-errno but build the remaining code with -fmath-errno. * string/Makefile [$(build-shared)] (tests): Add test-strerror-errno. [$(build-shared)] (LDLIBS-test-strerror-errno): New variable. * string/test-strerror-errno.c: New file. --- Makeconfig | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'Makeconfig') diff --git a/Makeconfig b/Makeconfig index 9dc1a6ba8e..07007c9459 100644 --- a/Makeconfig +++ b/Makeconfig @@ -831,8 +831,10 @@ endif # disable any optimization that assume default rounding mode. +math-flags = -frounding-math -# Build libc/libm using -fno-math-errno, but run testsuite with -fmath-errno. -+extra-math-flags = $(if $(filter libnldbl nonlib testsuite,$(in-module)),-fmath-errno,-fno-math-errno) +# Logically only "libnldbl", "nonlib" and "testsuite" should be using +# -fno-math-errno. However due to GCC bug #88576, only "libm" can use +# -fno-math-errno. ++extra-math-flags = $(if $(filter libm,$(in-module)),-fno-math-errno,-fmath-errno) # We might want to compile with some stack-protection flag. ifneq ($(stack-protector),) -- cgit 1.4.1