Disable floating point code/linking when possible.
Unless heap profiling is enabled, disable floating point code and don't link with libm. This, in combination with e.g. EXTRA_CFLAGS=-mno-sse on x64 systems, makes it possible to completely disable floating point register use. Some versions of glibc neglect to save/restore caller-saved floating point registers during dynamic lazy symbol loading, and the symbol loading code uses whatever malloc the application happens to have linked/loaded with, the result being potential floating point register corruption.
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@ -9,6 +9,13 @@ found in the git revision history:
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* 3.5.0 (XXX)
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Bug fixes:
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- Unless heap profiling is enabled, disable floating point code and don't link
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with libm. This, in combination with e.g. EXTRA_CFLAGS=-mno-sse on x64
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systems, makes it possible to completely disable floating point register
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use. Some versions of glibc neglect to save/restore caller-saved floating
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point registers during dynamic lazy symbol loading, and the symbol loading
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code uses whatever malloc the application happens to have linked/loaded
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with, the result being potential floating point register corruption.
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- Change the default private namespace prefix from empty to je_, and change
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--with-private-namespace-prefix so that it prepends an additional prefix
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rather than replacing je_. This reduces the likelihood of applications
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11
configure.ac
11
configure.ac
@ -356,11 +356,6 @@ AC_SUBST([ARFLAGS])
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AC_SUBST([AROUT])
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AC_SUBST([CC_MM])
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if test "x$abi" != "xpecoff"; then
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dnl Heap profiling uses the log(3) function.
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LIBS="$LIBS -lm"
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fi
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JE_COMPILABLE([__attribute__ syntax],
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[static __attribute__((unused)) void foo(void){}],
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[],
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@ -774,6 +769,12 @@ if test "x$enable_prof" = "x1" ; then
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AC_MSG_ERROR([Heap profiling requires TLS]);
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fi
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force_tls="1"
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if test "x$abi" != "xpecoff"; then
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dnl Heap profiling uses the log(3) function.
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LIBS="$LIBS -lm"
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fi
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AC_DEFINE([JEMALLOC_PROF], [ ])
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fi
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AC_SUBST([enable_prof])
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@ -320,6 +320,20 @@ prof_tdata_get(bool create)
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JEMALLOC_INLINE void
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prof_sample_threshold_update(prof_tdata_t *prof_tdata)
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{
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/*
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* The body of this function is compiled out unless heap profiling is
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* enabled, so that it is possible to compile jemalloc with floating
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* point support completely disabled. Avoiding floating point code is
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* important on memory-constrained systems, but it also enables a
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* workaround for versions of glibc that don't properly save/restore
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* floating point registers during dynamic lazy symbol loading (which
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* internally calls into whatever malloc implementation happens to be
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* integrated into the application). Note that some compilers (e.g.
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* gcc 4.8) may use floating point registers for fast memory moves, so
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* jemalloc must be compiled with such optimizations disabled (e.g.
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* -mno-sse) in order for the workaround to be complete.
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*/
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#ifdef JEMALLOC_PROF
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uint64_t r;
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double u;
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@ -349,6 +363,7 @@ prof_sample_threshold_update(prof_tdata_t *prof_tdata)
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prof_tdata->threshold = (uint64_t)(log(u) /
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log(1.0 - (1.0 / (double)((uint64_t)1U << opt_lg_prof_sample))))
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+ (uint64_t)1U;
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#endif
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}
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JEMALLOC_INLINE prof_ctx_t *
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