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fix GH-24262: default apache build to global-dynamic TLS #24301

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fix GH-24262: default apache build to global-dynamic TLS #24301

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0949f49
fix GH-24262: default apache build to global-dynamic TLS, use --with-…
henderkes Oct 13, 2026
3cb631a
advise to use -ftls-model=... instead, no extra configure option
henderkes Oct 15, 2026
f7d3a73
fast path for initial-exec
henderkes Oct 15, 2026
8f6a4bc
add extra_cflags to scan
henderkes Oct 15, 2026
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5 changes: 4 additions & 1 deletion TSRM/TSRM.c
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Original file line number Diff line number Diff line change
Expand Up @@ -855,7 +855,10 @@ TSRM_API void *tsrm_get_ls_cache(void)
/* Returns offset of tsrm_ls_cache slot from Thread Control Block address */
TSRM_API size_t tsrm_get_ls_cache_tcb_offset(void)
{/*{{{*/
#if defined(__APPLE__) && defined(__x86_64__)
#if defined(TSRM_TLS_MODEL_USE_DEFAULT) && defined(__PIC__) && !defined(__PIE__)
/* The compiler may use dynamic TLS. Do not force a static TLS relocation. */
return 0;
#elif defined(__APPLE__) && defined(__x86_64__)
// TODO: Implement support for fast JIT ZTS code ???
return 0;
#elif defined(__x86_64__) && defined(__GNUC__) && !defined(__FreeBSD__) && \
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9 changes: 7 additions & 2 deletions TSRM/TSRM.h
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Expand Up @@ -167,8 +167,13 @@ TSRM_API bool tsrm_is_managed_thread(void);
# define TSRM_TLS_MODEL_ATTR
# define TSRM_TLS_MODEL_DEFAULT
#elif defined(__PIC__) && !defined(__PIE__)
# define TSRM_TLS_MODEL_ATTR __attribute__((tls_model("initial-exec")))
# define TSRM_TLS_MODEL_INITIAL_EXEC
# if defined(TSRM_TLS_MODEL_USE_DEFAULT)
# define TSRM_TLS_MODEL_ATTR
# define TSRM_TLS_MODEL_DEFAULT
Comment on lines +170 to +172

@henderkes henderkes Oct 15, 2026

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This is still an extra block under PIC && !PIE instead of adding it above, because we want to keep the explicit local-exec choice in !PIC || PIE.

# else
# define TSRM_TLS_MODEL_ATTR __attribute__((tls_model("initial-exec")))
# define TSRM_TLS_MODEL_INITIAL_EXEC
# endif
#else
# define TSRM_TLS_MODEL_ATTR __attribute__((tls_model("local-exec")))
# define TSRM_TLS_MODEL_LOCAL_EXEC
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4 changes: 4 additions & 0 deletions UPGRADING.INTERNALS
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Expand Up @@ -267,6 +267,10 @@ PHP 8.6 INTERNALS UPGRADE NOTES
HAVE_STRUCT_STAT_ST_BLOCKS).
. Added a new configure option --disable-apache2-conf to prevent apxs from
editing httpd.conf during installation.
. Apache ZTS builds now use the compiler's default TLS model. To opt into
initial-exec, add -ftls-model=initial-exec to CFLAGS (and CXXFLAGS for C++
code). This may require increasing the host processes static TLS surplus,
e.g. by setting GLIBC_TUNABLES=glibc.rtld.optional_static_tls=8192.

- Windows build system changes:
. Function SETUP_OPENSSL() doesn't accept 6th argument anymore and doesn't
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17 changes: 17 additions & 0 deletions configure.ac
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Expand Up @@ -284,6 +284,9 @@ SAPI_SHARED=libs/$SAPI_LIBNAME_SHARED
SAPI_STATIC=libs/$SAPI_LIBNAME_STATIC
SAPI_LIBTOOL=libphp.la

dnl Set by SAPIs whose host program dlopen()s libphp without linking against it.
php_tsrm_dlopened_sapi=no

PHP_CONFIGURE_PART([Configuring SAPI modules])

esyscmd(./build/config-stubs sapi)
Expand Down Expand Up @@ -885,6 +888,20 @@ AS_VAR_IF([PHP_THREAD_SAFETY], [yes], [

AC_MSG_CHECKING([for POSIX threads])
AC_MSG_RESULT([yes])

AS_VAR_IF([php_tsrm_dlopened_sapi], [yes], [
php_tsrm_tls_model=
for flag in $CFLAGS $EXTRA_CFLAGS; do
AS_CASE([$flag], [-ftls-model=*], [php_tsrm_tls_model=$flag])
done

dnl Define TSRM_TLS_MODEL_USE_DEFAULT to avoid forcing static TLS in dlopened SAPIs.
dnl Omit it for explicit initial-exec to enable the TCB offset fast path.
AS_IF([test "$php_tsrm_tls_model" != "-ftls-model=initial-exec"], [
AC_DEFINE([TSRM_TLS_MODEL_USE_DEFAULT], [1],
[Define to 1 to use the compiler's default TLS model.])
])
])
])

PHP_ARG_ENABLE([rtld-now],
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5 changes: 5 additions & 0 deletions sapi/apache2handler/config.m4
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Expand Up @@ -94,6 +94,11 @@ if test "$PHP_APXS2" != "no"; then
LIBPHP_CFLAGS="-shared"
PHP_SUBST([LIBPHP_CFLAGS])

dnl httpd dlopen's libphp.so without linking against it, so we must
dnl use global-dynamic by default. Use -ftls-model=initial-exec to
dnl override the compiler choice, see UPGRADING.INTERNALS
php_tsrm_dlopened_sapi=yes

php_sapi_apache2handler_type=shared
AS_CASE([$host_alias],
[*aix*], [
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