303 lines
13 KiB
Diff
303 lines
13 KiB
Diff
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From 3d405634f43d39079ee93cdc59ed7fc0a5e8917a Mon Sep 17 00:00:00 2001
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From: KJ Tsanaktsidis <kj@kjtsanaktsidis.id.au>
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Date: Sun, 9 Jun 2024 21:15:39 +1000
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Subject: [PATCH] Extract hardening CFLAGS to a special $hardenflags variable
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This changes the automatic detection of -fstack-protector,
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-D_FORTIFY_SOURCE, and -mbranch-protection to write to $hardenflags
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instead of $XCFLAGS. The definition of $cflags is changed to
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"$hardenflags $orig_cflags $optflags $debugflags $warnflags" to match.
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Furthermore, these flags are _prepended_ to $hardenflags, rather than
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appended.
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The implications of doing this are as follows:
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* If a CRuby builder specifies cflags="-mbranch-protection=foobar" at
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the ./configure script, and the configure script detects that
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-mbranch-protection=pac-ret is accepted, then GCC will be invoked as
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"gcc -mbranch-protection=pac-ret -mbranch-protection=foobar". Since
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the last flags take precedence, that means that user-supplied values
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of these flags in $cflags will take priority.
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* Likewise, if a CRuby builder explicitly specifies
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"hardenflags=-mbranch-protection=foobar", because we _prepend_ to
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$hardenflags in our autoconf script, we will still invoke GCC as
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"gcc -mbranch-protection=pac-ret -mbranch-protection=foobar".
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* If a CRuby builder specifies CFLAGS="..." at the configure line,
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automatic detection of hardening flags is ignored as before.
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* C extensions will _also_ be built with hardening flags now as well
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(this was not the case by default before because the detected flags
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went into $XCFLAGS).
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Additionally, as part of this work, I changed how the detection of
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PAC/BTI in Context.S works. Rather than appending the autodetected
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option to ASFLAGS, we simply compile a set of test programs with the
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actual CFLAGS in use to determine what PAC/BTI settings were actually
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chosen by the builder. Context.S is made aware of these choices through
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some custom macros.
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The result of this work is that:
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* Ruby will continue to choose some sensible defaults for hardening
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options for the C compiler
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* Distributors are able to specify CFLAGS that are consistent with their
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distribution and override these defaults
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* Context.S will react to whatever -mbranch-protection is actually in
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use, not what was autodetected
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* Extensions get built with hardening flags too.
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[Bug #20154]
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[Bug #20520]
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---
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configure.ac | 81 ++++++++++++++++++++++++++++++-----
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coroutine/arm64/Context.S | 14 +++---
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template/Makefile.in | 1 +
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tool/m4/ruby_append_option.m4 | 4 ++
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tool/m4/ruby_try_cflags.m4 | 17 ++++++++
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5 files changed, 100 insertions(+), 17 deletions(-)
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diff --git a/configure.ac b/configure.ac
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index f35fad6a362611..0da15772d36671 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -354,7 +354,7 @@ test -z "$warnflags" ||
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AS_IF([test -z "${CFLAGS+set}"], [
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cflags=`echo " $cflags " | sed "$cflagspat;s/^ *//;s/ *$//"`
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orig_cflags="$cflags"
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- cflags="$cflags "'${optflags} ${debugflags} ${warnflags}'
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+ cflags='${hardenflags} '"$cflags "'${optflags} ${debugflags} ${warnflags}'
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])
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dnl AS_IF([test -z "${CXXFLAGS+set}"], [
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dnl cxxflags=`echo " $cxxflags " | sed "$cflagspat;s/^ *//;s/ *$//"`
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@@ -802,7 +802,7 @@ AS_IF([test "$GCC" = yes], [
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[fortify_source=$enableval])
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AS_IF([test "x$fortify_source" != xno], [
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RUBY_TRY_CFLAGS([$optflags -D_FORTIFY_SOURCE=2],
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- [RUBY_APPEND_OPTION(XCFLAGS, -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2)], [],
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+ [RUBY_PREPEND_OPTION(hardenflags, -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2)], [],
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[@%:@include <stdio.h>])
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])
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@@ -823,20 +823,24 @@ AS_IF([test "$GCC" = yes], [
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AC_MSG_CHECKING([for -fstack-protector])
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AC_MSG_RESULT(["$stack_protector"])
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AS_CASE(["$stack_protector"], [-*], [
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- RUBY_APPEND_OPTION(XCFLAGS, $stack_protector)
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- RUBY_APPEND_OPTION(XLDFLAGS, $stack_protector)
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- RUBY_APPEND_OPTION(LDFLAGS, $stack_protector)
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+ RUBY_PREPEND_OPTION(hardenflags, $stack_protector)
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+ RUBY_APPEND_OPTION(XLDFLAGS, $stack_protector)
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+ RUBY_APPEND_OPTION(LDFLAGS, $stack_protector)
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])
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# aarch64 branch protection
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AS_CASE(["$target_cpu"], [aarch64], [
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AS_FOR(option, opt, [-mbranch-protection=pac-ret -msign-return-address=all], [
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- RUBY_TRY_CFLAGS(option, [branch_protection=yes], [branch_protection=no])
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+ # Try these flags in the _prepended_ position - i.e. we want to try building a program
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+ # with CFLAGS="-mbranch-protection=pac-ret $CFLAGS". If the builder has provided different
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+ # branch protection flags in CFLAGS, we don't want to overwrite those. We just want to
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+ # find some branch protection flags which work if none were provided.
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+ RUBY_TRY_CFLAGS_PREPEND(option, [branch_protection=yes], [branch_protection=no])
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AS_IF([test "x$branch_protection" = xyes], [
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- # C compiler and assembler must be consistent for -mbranch-protection
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- # since they both check `__ARM_FEATURE_PAC_DEFAULT` definition.
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- RUBY_APPEND_OPTION(XCFLAGS, option)
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- RUBY_APPEND_OPTION(ASFLAGS, option)
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+ # _prepend_ the options to CFLAGS, so that user-provided flags will overwrite them.
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+ # These CFLAGS are used during the configure script to compile further test programs;
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+ # however, $harden_flags is prepended separately to CFLAGS at the end of the script.
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+ RUBY_PREPEND_OPTION(hardenflags, $opt)
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break
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])
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])
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@@ -985,6 +989,59 @@ test -z "${ac_env_CFLAGS_set}" -a -n "${cflags+set}" && eval CFLAGS="\"$cflags $
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test -z "${ac_env_CXXFLAGS_set}" -a -n "${cxxflags+set}" && eval CXXFLAGS="\"$cxxflags $ARCH_FLAG\""
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}
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+# The lines above expand out the $cflags/$optflags/$debugflags/$hardenflags variables into the
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+# CFLAGS variable. So, at this point, we have a $CFLAGS var with the actual compiler flags we're
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+# going to use.
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+# That means this is the right time to check what branch protection flags are going to be in use
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+# and define appropriate macros for use in Context.S based on this
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+AS_CASE(["$target_cpu"], [aarch64], [
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+ AC_CACHE_CHECK([whether __ARM_FEATURE_BTI_DEFAULT is defined],
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+ rb_cv_aarch64_bti_enabled,
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+ AC_COMPILE_IFELSE(
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+ [AC_LANG_PROGRAM([[
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+ @%:@ifndef __ARM_FEATURE_BTI_DEFAULT
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+ @%:@error "__ARM_FEATURE_BTI_DEFAULT not defined"
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+ @%:@endif
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+ ]])],
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+ [rb_cv_aarch64_bti_enabled=yes],
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+ [rb_cv_aarch64_bti_enabled=no])
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+ )
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+ AS_IF([test "$rb_cv_aarch64_bti_enabled" = yes],
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+ AC_DEFINE(RUBY_AARCH64_BTI_ENABLED, 1))
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+ AC_CACHE_CHECK([whether __ARM_FEATURE_PAC_DEFAULT is defined],
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+ rb_cv_aarch64_pac_enabled,
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+ AC_COMPILE_IFELSE(
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+ [AC_LANG_PROGRAM([[
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+ @%:@ifndef __ARM_FEATURE_PAC_DEFAULT
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+ @%:@error "__ARM_FEATURE_PAC_DEFAULT not defined"
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+ @%:@endif
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+ ]])],
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+ [rb_cv_aarch64_pac_enabled=yes],
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+ [rb_cv_aarch64_pac_enabled=no])
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+ )
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+ AS_IF([test "$rb_cv_aarch64_pac_enabled" = yes],
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+ AC_DEFINE(RUBY_AARCH64_PAC_ENABLED, 1))
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+ # Context.S will only ever sign its return address with the A-key; it doesn't support
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+ # the B-key at the moment.
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+ AS_IF([test "$rb_cv_aarch64_pac_enabled" = yes], [
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+ AC_CACHE_CHECK([whether __ARM_FEATURE_PAC_DEFAULT specifies the b-key bit 0x02],
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+ rb_cv_aarch64_pac_b_key,
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+ AC_COMPILE_IFELSE(
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+ [AC_LANG_PROGRAM([[
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+ @%:@ifdef __ARM_FEATURE_PAC_DEFAULT
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+ @%:@if __ARM_FEATURE_PAC_DEFAULT & 0x02
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+ @%:@error "__ARM_FEATURE_PAC_DEFAULT specifies B key"
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+ @%:@endif
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+ @%:@endif
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+ ]])],
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+ [rb_cv_aarch64_pac_b_key=no],
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+ [rb_cv_aarch64_pac_b_key=yes])
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+ )
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+ AS_IF([test "$rb_cv_aarch64_pac_b_key" = yes],
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+ AC_MSG_ERROR(-mbranch-protection flag specified b-key but Ruby's Context.S does not support this yet.))
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+ ])
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+])
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+
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AC_CACHE_CHECK([whether compiler has statement and declarations in expressions],
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rb_cv_have_stmt_and_decl_in_expr,
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[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[ __extension__ ({ int a = 0; a; }); ]])],
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@@ -4215,12 +4272,13 @@ AS_IF([test "${ARCH_FLAG}"], [
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rb_cv_warnflags=`echo "$rb_cv_warnflags" | sed 's/^ *//;s/ *$//'`
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warnflags="$rb_cv_warnflags"
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AC_SUBST(cppflags)dnl
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-AC_SUBST(cflags, ["${orig_cflags:+$orig_cflags }"'${optflags} ${debugflags} ${warnflags}'])dnl
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+AC_SUBST(cflags, ['${hardenflags} '"${orig_cflags:+$orig_cflags }"' ${optflags} ${debugflags} ${warnflags}'])dnl
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AC_SUBST(cxxflags)dnl
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AC_SUBST(optflags)dnl
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AC_SUBST(debugflags)dnl
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AC_SUBST(warnflags)dnl
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AC_SUBST(strict_warnflags)dnl
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+AC_SUBST(hardenflags)dnl
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AC_SUBST(XCFLAGS)dnl
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AC_SUBST(XLDFLAGS)dnl
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AC_SUBST(EXTLDFLAGS)dnl
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@@ -4688,6 +4746,7 @@ config_summary "DLDFLAGS" "$DLDFLAGS"
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config_summary "optflags" "$optflags"
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config_summary "debugflags" "$debugflags"
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config_summary "warnflags" "$warnflags"
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+config_summary "hardenflags" "$hardenflags"
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config_summary "strip command" "$STRIP"
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config_summary "install doc" "$DOCTARGETS"
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config_summary "YJIT support" "$YJIT_SUPPORT"
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diff --git a/coroutine/arm64/Context.S b/coroutine/arm64/Context.S
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index 5251ab214df1f0..54611a247e2f66 100644
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--- a/coroutine/arm64/Context.S
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+++ b/coroutine/arm64/Context.S
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@@ -5,6 +5,8 @@
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## Copyright, 2018, by Samuel Williams.
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##
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+#include "ruby/config.h"
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+
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#define TOKEN_PASTE(x,y) x##y
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#define PREFIXED_SYMBOL(prefix,name) TOKEN_PASTE(prefix,name)
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@@ -27,10 +29,10 @@
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.global PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer)
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PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer):
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-#if defined(__ARM_FEATURE_PAC_DEFAULT) && (__ARM_FEATURE_PAC_DEFAULT != 0)
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+#if defined(RUBY_AARCH64_PAC_ENABLED)
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# paciasp (it also acts as BTI landing pad, so no need to insert BTI also)
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hint #25
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-#elif defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT != 0)
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+#elif defined(RUBY_AARCH64_BTI_ENABLED)
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# For the the case PAC is not enabled but BTI is.
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# bti c
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hint #34
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@@ -73,7 +75,7 @@ PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer):
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# Pop stack frame
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add sp, sp, 0xa0
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-#if defined(__ARM_FEATURE_PAC_DEFAULT) && (__ARM_FEATURE_PAC_DEFAULT != 0)
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+#if defined(RUBY_AARCH64_PAC_ENABLED)
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# autiasp: Authenticate x30 (LR) with SP and key A
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hint #29
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#endif
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@@ -85,18 +87,18 @@ PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer):
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.section .note.GNU-stack,"",%progbits
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#endif
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-#if __ARM_FEATURE_BTI_DEFAULT != 0 || __ARM_FEATURE_PAC_DEFAULT != 0
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+#if defined(RUBY_AARCH64_BTI_ENABLED) || defined(RUBY_AARCH64_PAC_ENABLED)
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/* See "ELF for the Arm 64-bit Architecture (AArch64)"
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https://github.com/ARM-software/abi-aa/blob/2023Q3/aaelf64/aaelf64.rst#program-property */
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# define GNU_PROPERTY_AARCH64_FEATURE_1_BTI (1<<0)
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# define GNU_PROPERTY_AARCH64_FEATURE_1_PAC (1<<1)
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-# if __ARM_FEATURE_BTI_DEFAULT != 0
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+# if defined(RUBY_AARCH64_BTI_ENABLED)
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# define BTI_FLAG GNU_PROPERTY_AARCH64_FEATURE_1_BTI
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# else
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# define BTI_FLAG 0
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# endif
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-# if __ARM_FEATURE_PAC_DEFAULT != 0
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+# if defined(RUBY_AARCH64_PAC_ENABLED)
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# define PAC_FLAG GNU_PROPERTY_AARCH64_FEATURE_1_PAC
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# else
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# define PAC_FLAG 0
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diff --git a/template/Makefile.in b/template/Makefile.in
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index 033ac56cb38886..abb4469777ce8a 100644
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--- a/template/Makefile.in
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+++ b/template/Makefile.in
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@@ -89,6 +89,7 @@ cflags = @cflags@
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optflags = @optflags@
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debugflags = @debugflags@
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warnflags = @warnflags@ @strict_warnflags@
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+hardenflags = @hardenflags@
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cppflags = @cppflags@
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incflags = @incflags@
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RUBY_DEVEL = @RUBY_DEVEL@ # "yes" or empty
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diff --git a/tool/m4/ruby_append_option.m4 b/tool/m4/ruby_append_option.m4
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index ff828d2162c22f..98359fa1f95f52 100644
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--- a/tool/m4/ruby_append_option.m4
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+++ b/tool/m4/ruby_append_option.m4
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@@ -3,3 +3,7 @@ AC_DEFUN([RUBY_APPEND_OPTION],
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[# RUBY_APPEND_OPTION($1)
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AS_CASE([" [$]{$1-} "],
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[*" $2 "*], [], [' '], [ $1="$2"], [ $1="[$]$1 $2"])])dnl
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+AC_DEFUN([RUBY_PREPEND_OPTION],
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+ [# RUBY_APPEND_OPTION($1)
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+ AS_CASE([" [$]{$1-} "],
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+ [*" $2 "*], [], [' '], [ $1="$2"], [ $1="$2 [$]$1"])])dnl
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diff --git a/tool/m4/ruby_try_cflags.m4 b/tool/m4/ruby_try_cflags.m4
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index b74718fe5e1cef..b397642aad9ca2 100644
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--- a/tool/m4/ruby_try_cflags.m4
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+++ b/tool/m4/ruby_try_cflags.m4
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@@ -22,3 +22,20 @@ AC_DEFUN([RUBY_TRY_CFLAGS], [
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AC_MSG_RESULT(no)],
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[$4], [$5])
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])dnl
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+
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+AC_DEFUN([_RUBY_TRY_CFLAGS_PREPEND], [
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+ RUBY_WERROR_FLAG([
|
||
|
|
+ CFLAGS="$1 [$]CFLAGS"
|
||
|
|
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[$4]], [[$5]])],
|
||
|
|
+ [$2], [$3])
|
||
|
|
+ ])dnl
|
||
|
|
+])dnl
|
||
|
|
+AC_DEFUN([RUBY_TRY_CFLAGS_PREPEND], [
|
||
|
|
+ AC_MSG_CHECKING([whether ]$1[ is accepted as CFLAGS])dnl
|
||
|
|
+ _RUBY_TRY_CFLAGS_PREPEND([$1],
|
||
|
|
+ [$2
|
||
|
|
+ AC_MSG_RESULT(yes)],
|
||
|
|
+ [$3
|
||
|
|
+ AC_MSG_RESULT(no)],
|
||
|
|
+ [$4], [$5])
|
||
|
|
+])dnl
|