mirror of https://github.com/xemu-project/xemu.git
Workaround for macos mprotect
Workaround for target_page vs -flto -----BEGIN PGP SIGNATURE----- iQFRBAABCgA7FiEEekgeeIaLTbaoWgXAZN846K9+IV8FAmBamHwdHHJpY2hhcmQu aGVuZGVyc29uQGxpbmFyby5vcmcACgkQZN846K9+IV/kfwf+PAwnkdobFLOiXoYQ 545SW3wwS0AR1dd1+XqIPf9GHWLm91rQCVQ/Q0po9t+EHHFihbtePc3p9djnJQ1/ 3QAFtdpte7GJfI9Dk4+oYg3dZBWznDzee1aQRtN+Qh1k7eWJXY58Ezi1KgwUlWw0 LM9+xuKNYuzys8oTBg70xDENVWajXLDEBKH/AacqF5pAIsuiOb/wm3nNzQ9gc03M bQk+v7lkX9jrgFl4M+xJLusKDBXgVDpqWKObn048hml+99e5hdhAluWqV77lrxac dwUmUB465xnqkcibwgk73+RWSaOpKosCtyZn4TIgiMllIv2MYjg9aodrO/4efrJq PcDwAw== =eK71 -----END PGP SIGNATURE----- Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20210323' into staging Workaround for macos mprotect Workaround for target_page vs -flto # gpg: Signature made Wed 24 Mar 2021 01:40:12 GMT # gpg: using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F # gpg: issuer "richard.henderson@linaro.org" # gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full] # Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A 05C0 64DF 38E8 AF7E 215F * remotes/rth/tags/pull-tcg-20210323: exec: Build page-vary-common.c with -fno-lto exec: Extract 'page-vary.h' header exec: Rename exec-vary.c as page-vary.c tcg: Workaround macOS 11.2 mprotect bug tcg: Do not set guard pages on the rx portion of code_gen_buffer Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell
commit
01874b15d3
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@ -117,6 +117,8 @@ R: Paolo Bonzini <pbonzini@redhat.com>
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S: Maintained
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F: softmmu/cpus.c
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F: cpus-common.c
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F: page-vary.c
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F: page-vary-common.c
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F: accel/tcg/
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F: accel/stubs/tcg-stub.c
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F: util/cacheinfo.c
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@ -4889,21 +4889,6 @@ if test "$plugins" = "yes" &&
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"for this purpose. You can't build with --static."
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fi
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########################################
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# See if __attribute__((alias)) is supported.
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# This false for Xcode 9, but has been remedied for Xcode 10.
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# Unfortunately, travis uses Xcode 9 by default.
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attralias=no
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cat > $TMPC << EOF
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int x = 1;
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extern const int y __attribute__((alias("x")));
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int main(void) { return 0; }
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EOF
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if compile_prog "" "" ; then
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attralias=yes
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fi
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########################################
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# check if getauxval is available.
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@ -5935,10 +5920,6 @@ if test "$atomic64" = "yes" ; then
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echo "CONFIG_ATOMIC64=y" >> $config_host_mak
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fi
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if test "$attralias" = "yes" ; then
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echo "CONFIG_ATTRIBUTE_ALIAS=y" >> $config_host_mak
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fi
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if test "$getauxval" = "yes" ; then
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echo "CONFIG_GETAUXVAL=y" >> $config_host_mak
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fi
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108
exec-vary.c
108
exec-vary.c
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@ -1,108 +0,0 @@
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/*
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* Variable page size handling
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "qemu-common.h"
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#define IN_EXEC_VARY 1
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#include "exec/exec-all.h"
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#ifdef TARGET_PAGE_BITS_VARY
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# ifdef CONFIG_ATTRIBUTE_ALIAS
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/*
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* We want to declare the "target_page" variable as const, which tells
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* the compiler that it can cache any value that it reads across calls.
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* This avoids multiple assertions and multiple reads within any one user.
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*
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* This works because we finish initializing the data before we ever read
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* from the "target_page" symbol.
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*
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* This also requires that we have a non-constant symbol by which we can
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* perform the actual initialization, and which forces the data to be
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* allocated within writable memory. Thus "init_target_page", and we use
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* that symbol exclusively in the two functions that initialize this value.
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*
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* The "target_page" symbol is created as an alias of "init_target_page".
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*/
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static TargetPageBits init_target_page;
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/*
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* Note that this is *not* a redundant decl, this is the definition of
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* the "target_page" symbol. The syntax for this definition requires
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* the use of the extern keyword. This seems to be a GCC bug in
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* either the syntax for the alias attribute or in -Wredundant-decls.
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*
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* See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91765
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*/
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# pragma GCC diagnostic push
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# pragma GCC diagnostic ignored "-Wredundant-decls"
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extern const TargetPageBits target_page
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__attribute__((alias("init_target_page")));
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# pragma GCC diagnostic pop
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# else
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/*
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* When aliases are not supported then we force two different declarations,
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* by way of suppressing the header declaration with IN_EXEC_VARY.
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* We assume that on such an old compiler, LTO cannot be used, and so the
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* compiler cannot not detect the mismatched declarations, and all is well.
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*/
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TargetPageBits target_page;
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# define init_target_page target_page
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# endif
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#endif
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bool set_preferred_target_page_bits(int bits)
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{
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/*
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* The target page size is the lowest common denominator for all
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* the CPUs in the system, so we can only make it smaller, never
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* larger. And we can't make it smaller once we've committed to
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* a particular size.
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*/
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#ifdef TARGET_PAGE_BITS_VARY
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assert(bits >= TARGET_PAGE_BITS_MIN);
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if (init_target_page.bits == 0 || init_target_page.bits > bits) {
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if (init_target_page.decided) {
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return false;
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}
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init_target_page.bits = bits;
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}
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#endif
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return true;
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}
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void finalize_target_page_bits(void)
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{
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#ifdef TARGET_PAGE_BITS_VARY
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if (init_target_page.bits == 0) {
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init_target_page.bits = TARGET_PAGE_BITS_MIN;
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}
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init_target_page.mask = (target_long)-1 << init_target_page.bits;
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init_target_page.decided = true;
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/*
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* For the benefit of an -flto build, prevent the compiler from
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* hoisting a read from target_page before we finish initializing.
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*/
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barrier();
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#endif
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}
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@ -215,22 +215,15 @@ static inline void stl_phys_notdirty(AddressSpace *as, hwaddr addr, uint32_t val
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/* page related stuff */
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#ifdef TARGET_PAGE_BITS_VARY
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typedef struct {
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bool decided;
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int bits;
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target_long mask;
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} TargetPageBits;
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#if defined(CONFIG_ATTRIBUTE_ALIAS) || !defined(IN_EXEC_VARY)
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# include "exec/page-vary.h"
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extern const TargetPageBits target_page;
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#else
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extern TargetPageBits target_page;
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#endif
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#ifdef CONFIG_DEBUG_TCG
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#define TARGET_PAGE_BITS ({ assert(target_page.decided); target_page.bits; })
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#define TARGET_PAGE_MASK ({ assert(target_page.decided); target_page.mask; })
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#define TARGET_PAGE_MASK ({ assert(target_page.decided); \
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(target_long)target_page.mask; })
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#else
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#define TARGET_PAGE_BITS target_page.bits
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#define TARGET_PAGE_MASK target_page.mask
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#define TARGET_PAGE_MASK ((target_long)target_page.mask)
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#endif
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#define TARGET_PAGE_SIZE (-(int)TARGET_PAGE_MASK)
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#else
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@ -0,0 +1,34 @@
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/*
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* Definitions for cpus with variable page sizes.
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef EXEC_PAGE_VARY_H
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#define EXEC_PAGE_VARY_H
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typedef struct {
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bool decided;
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int bits;
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uint64_t mask;
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} TargetPageBits;
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#ifdef IN_PAGE_VARY
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extern bool set_preferred_target_page_bits_common(int bits);
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extern void finalize_target_page_bits_common(int min);
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#endif
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#endif /* EXEC_PAGE_VARY_H */
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21
meson.build
21
meson.build
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@ -1933,7 +1933,6 @@ subdir('softmmu')
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common_ss.add(capstone)
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specific_ss.add(files('cpu.c', 'disas.c', 'gdbstub.c'), capstone)
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specific_ss.add(files('exec-vary.c'))
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specific_ss.add(when: 'CONFIG_TCG', if_true: files(
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'fpu/softfloat.c',
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'tcg/optimize.c',
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@ -1945,6 +1944,26 @@ specific_ss.add(when: 'CONFIG_TCG', if_true: files(
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))
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specific_ss.add(when: 'CONFIG_TCG_INTERPRETER', if_true: files('tcg/tci.c'))
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# Work around a gcc bug/misfeature wherein constant propagation looks
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# through an alias:
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99696
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# to guess that a const variable is always zero. Without lto, this is
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# impossible, as the alias is restricted to page-vary-common.c. Indeed,
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# without lto, not even the alias is required -- we simply use different
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# declarations in different compilation units.
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pagevary = files('page-vary-common.c')
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if get_option('b_lto')
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pagevary_flags = ['-fno-lto']
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if get_option('cfi')
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pagevary_flags += '-fno-sanitize=cfi-icall'
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endif
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pagevary = static_library('page-vary-common', sources: pagevary,
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c_args: pagevary_flags)
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pagevary = declare_dependency(link_with: pagevary)
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endif
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common_ss.add(pagevary)
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specific_ss.add(files('page-vary.c'))
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subdir('backends')
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subdir('disas')
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subdir('migration')
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@ -0,0 +1,54 @@
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/*
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* Variable page size handling -- target independent part.
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
|
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
|
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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||||
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#define IN_PAGE_VARY 1
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#include "qemu/osdep.h"
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#include "qemu-common.h"
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#include "exec/page-vary.h"
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/* WARNING: This file must *not* be complied with -flto. */
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TargetPageBits target_page;
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bool set_preferred_target_page_bits_common(int bits)
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{
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/*
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* The target page size is the lowest common denominator for all
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* the CPUs in the system, so we can only make it smaller, never
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* larger. And we can't make it smaller once we've committed to
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* a particular size.
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*/
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if (target_page.bits == 0 || target_page.bits > bits) {
|
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if (target_page.decided) {
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return false;
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}
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target_page.bits = bits;
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}
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return true;
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}
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void finalize_target_page_bits_common(int min)
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{
|
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if (target_page.bits == 0) {
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target_page.bits = min;
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}
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target_page.mask = -1ull << target_page.bits;
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target_page.decided = true;
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}
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|
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@ -0,0 +1,41 @@
|
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/*
|
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* Variable page size handling -- target specific part.
|
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*
|
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* Copyright (c) 2003 Fabrice Bellard
|
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*
|
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* This library is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU Lesser General Public
|
||||
* License as published by the Free Software Foundation; either
|
||||
* version 2.1 of the License, or (at your option) any later version.
|
||||
*
|
||||
* This library is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
* Lesser General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU Lesser General Public
|
||||
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
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|
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#define IN_PAGE_VARY 1
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#include "qemu/osdep.h"
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#include "qemu-common.h"
|
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#include "exec/exec-all.h"
|
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bool set_preferred_target_page_bits(int bits)
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{
|
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#ifdef TARGET_PAGE_BITS_VARY
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assert(bits >= TARGET_PAGE_BITS_MIN);
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return set_preferred_target_page_bits_common(bits);
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#else
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return true;
|
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#endif
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}
|
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|
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void finalize_target_page_bits(void)
|
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{
|
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#ifdef TARGET_PAGE_BITS_VARY
|
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finalize_target_page_bits_common(TARGET_PAGE_BITS_MIN);
|
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#endif
|
||||
}
|
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22
tcg/tcg.c
22
tcg/tcg.c
|
|
@ -828,7 +828,6 @@ void tcg_region_init(void)
|
|||
size_t region_size;
|
||||
size_t n_regions;
|
||||
size_t i;
|
||||
uintptr_t splitwx_diff;
|
||||
|
||||
n_regions = tcg_n_regions();
|
||||
|
||||
|
|
@ -858,19 +857,22 @@ void tcg_region_init(void)
|
|||
/* account for that last guard page */
|
||||
region.end -= page_size;
|
||||
|
||||
/* set guard pages */
|
||||
splitwx_diff = tcg_splitwx_diff;
|
||||
/*
|
||||
* Set guard pages in the rw buffer, as that's the one into which
|
||||
* buffer overruns could occur. Do not set guard pages in the rx
|
||||
* buffer -- let that one use hugepages throughout.
|
||||
*/
|
||||
for (i = 0; i < region.n; i++) {
|
||||
void *start, *end;
|
||||
int rc;
|
||||
|
||||
tcg_region_bounds(i, &start, &end);
|
||||
rc = qemu_mprotect_none(end, page_size);
|
||||
g_assert(!rc);
|
||||
if (splitwx_diff) {
|
||||
rc = qemu_mprotect_none(end + splitwx_diff, page_size);
|
||||
g_assert(!rc);
|
||||
}
|
||||
|
||||
/*
|
||||
* macOS 11.2 has a bug (Apple Feedback FB8994773) in which mprotect
|
||||
* rejects a permission change from RWX -> NONE. Guard pages are
|
||||
* nice for bug detection but are not essential; ignore any failure.
|
||||
*/
|
||||
(void)qemu_mprotect_none(end, page_size);
|
||||
}
|
||||
|
||||
tcg_region_trees_init();
|
||||
|
|
|
|||
Loading…
Reference in New Issue