Fix linker failure when building opcache statically

This fixes the following linker error:

    TLS transition from R_X86_64_TLSGD to R_X86_64_GOTTPOFF against
    `_tsrm_ls_cache' at 0x12fc3 in section `.text' failed"

The error arises from how we obtain information about the _tsrm_ls_cache TLS
variable for use in JIT'ed code:

Normally, TLS variables are resolved via linker relocations [1], which of course
can not be used in JIT'ed code. Therefore we emit the relocation in AOT code and
use the result in JIT.

Specifically we use a fragment of the "General Dynamic" code sequence described
in [1]. Using the full code sequence would give us the address of the variable
in the current thread. Therefore we only use a fragment that gives us the
variable's TLS index and offset.

When Opcache is statically linked into the binary, linkers attempt to relax
(rewrite) this code sequence into a more efficient one. However, this fails
because they will not recognize the code sequence.

We now take a different approach:

 * Emit the exact full code sequence expected by linkers
 * Extract the TLS index/offset or TCB offset by inspecting the ASM code, rather
   than executing it (execution would give us the thread-local address).
 * This is done in a conservative way so that if the linker did
   something we didn't expect, we fallback to a safer (but slower) mechanism.

[1] https://www.akkadia.org/drepper/tls.pdf

Author: arnaud-lb

.github/actions/freebsd/action.yml

@@ -41,7 +41,8 @@ runs:
             webp \
             libavif \
             `#sqlite3` \
-            curl
+            curl \
+            gcc
 
           ./buildconf -f
           ./configure \
@@ -108,3 +109,6 @@ runs:
             --show-slow 1000 \
             --set-timeout 120 \
             -d zend_extension=opcache.so
+
+          export TLSC=$(pwd)/ext/opcache/jit/tls/zend_jit_tls_x86_64.c
+          ./ext/opcache/jit/tls/testing/test.sh

.github/actions/test-tls-alpine/action.yml

@@ -0,0 +1,10 @@
+name: Test TLS
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      run: |
+        set -x
+        apk add clang gcc binutils-gold lld
+        export TLSC=$(pwd)/ext/opcache/jit/tls/zend_jit_tls_x86_64.c
+        ./ext/opcache/jit/tls/testing/test.sh

.github/actions/test-tls-macos/action.yml

@@ -0,0 +1,9 @@
+name: Test TLS
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      run: |
+        set -x
+        export TLSC=$(pwd)/ext/opcache/jit/tls/zend_jit_tls_darwin.c
+        ./ext/opcache/jit/tls/testing/test.sh

.github/actions/test-tls-x32/action.yml

@@ -0,0 +1,12 @@
+name: Test TLS
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      run: |
+        set -x
+        export DEBIAN_FRONTEND=noninteractive
+        apt-get install -y gcc clang lld
+        export TLSC=$(pwd)/ext/opcache/jit/tls/zend_jit_tls_x86.c
+        export MACHINE=-m32
+        ./ext/opcache/jit/tls/testing/test.sh

.github/actions/test-tls-x64/action.yml

@@ -0,0 +1,11 @@
+name: Test TLS
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      run: |
+        set -x
+        export DEBIAN_FRONTEND=noninteractive
+        sudo apt-get install -y gcc clang lld
+        export TLSC=$(pwd)/ext/opcache/jit/tls/zend_jit_tls_x86_64.c
+        ./ext/opcache/jit/tls/testing/test.sh

.github/workflows/nightly.yml

@@ -134,6 +134,8 @@ jobs:
             --asan -x
             -d zend_extension=opcache.so
             -d opcache.enable_cli=1
+      - name: Test TLS resolution
+        uses: ./.github/actions/test-tls-alpine
       - name: Notify Slack
         if: failure()
         uses: ./.github/actions/notify-slack
@@ -266,6 +268,9 @@ jobs:
             ${{ matrix.run_tests_parameters }}
             -d zend_extension=opcache.so
             -d opcache.enable_cli=1
+      - name: Test TLS resolution
+        if: matrix.debug && matrix.zts && !matrix.asan
+        uses: ./.github/actions/test-tls-x64
       - name: Verify generated files are up to date
         uses: ./.github/actions/verify-generated-files
       - name: Notify Slack
@@ -355,6 +360,9 @@ jobs:
             ${{ matrix.run_tests_parameters }}
             -d zend_extension=opcache.so
             -d opcache.enable_cli=1
+      - name: Test TLS resolution
+        if: matrix.debug && matrix.zts
+        uses: ./.github/actions/test-tls-x32
       - name: Notify Slack
         if: failure()
         uses: ./.github/actions/notify-slack
@@ -414,6 +422,10 @@ jobs:
           runTestsParameters: >-
             -d zend_extension=opcache.so
             -d opcache.enable_cli=1
+      - name: Test TLS resolution
+        # JIT+ZTS not supported yet on ARM64
+        if: matrix.os != '14' && matrix.debug && matrix.zts
+        uses: ./.github/actions/test-tls-macos
       - name: Verify generated files are up to date
         uses: ./.github/actions/verify-generated-files
       - name: Notify Slack

ext/opcache/config.m4

@@ -73,19 +73,23 @@ if test "$PHP_OPCACHE" != "no"; then
         IR_TARGET=IR_TARGET_X64
         DASM_FLAGS="-D X64APPLE=1 -D X64=1"
         DASM_ARCH="x86"
+        TLS_TARGET="darwin"
       ],
       [*x86_64*|amd64-*-freebsd*], [
         IR_TARGET=IR_TARGET_X64
         DASM_FLAGS="-D X64=1"
         DASM_ARCH="x86"
+        TLS_TARGET="x86_64"
       ],
       [[i[34567]86*|x86*]], [
         IR_TARGET=IR_TARGET_X86
         DASM_ARCH="x86"
+        TLS_TARGET="x86"
       ],
       [aarch64*], [
         IR_TARGET=IR_TARGET_AARCH64
         DASM_ARCH="aarch64"
+        TLS_TARGET="aarch64"
       ])
 
     AS_VAR_IF([PHP_CAPSTONE], [yes],
@@ -102,6 +106,10 @@ if test "$PHP_OPCACHE" != "no"; then
 
     JIT_CFLAGS="-I@ext_builddir@/jit/ir -D$IR_TARGET -DIR_PHP"
     AS_VAR_IF([ZEND_DEBUG], [yes], [JIT_CFLAGS="$JIT_CFLAGS -DIR_DEBUG"])
+
+    AS_VAR_IF([PHP_THREAD_SAFETY], [yes], [
+      ZEND_JIT_SRC="$ZEND_JIT_SRC jit/tls/zend_jit_tls_$TLS_TARGET.c"
+    ])
   ])
 
   AC_CHECK_FUNCS([mprotect shm_create_largepage])

ext/opcache/config.w32

@@ -33,6 +33,7 @@ if (PHP_OPCACHE != "no") {
 			DEFINE("IR_TARGET", ir_target);
 			DEFINE("DASM_FLAGS", dasm_flags);
 			DEFINE("DASM_ARCH", "x86");
+			DEFINE("TLS_TARGET", "win");
 
 			AC_DEFINE('HAVE_JIT', 1, 'Define to 1 to enable JIT.');
 
@@ -52,6 +53,11 @@ if (PHP_OPCACHE != "no") {
 			ADD_SOURCES(configure_module_dirname + "\\jit",
 				"zend_jit.c zend_jit_vm_helpers.c",
 				"opcache", "ext\\opcache\\jit");
+			if (PHP_ZTS == "yes") {
+				ADD_SOURCES(configure_module_dirname + "\\jit\\tls",
+					"zend_jit_tls_win.c",
+					"opcache", "ext\\opcache\\jit\\tls");
+			}
 			ADD_SOURCES(configure_module_dirname + "\\jit\\ir",
 				"ir.c", "opcache", "ext\\opcache\\jit\\ir");
 			ADD_SOURCES(configure_module_dirname + "\\jit\\ir",

ext/opcache/jit/tls/testing/.gitignore

@@ -0,0 +1,4 @@
+*.so
+*.o
+main
+main.dSYM