add effective user context manipulation routines

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.16)
 project(kphp
         VERSION 1.0.1
-        LANGUAGES CXX
+        LANGUAGES CXX ASM
         DESCRIPTION "Compiler for PHP (aka KPHP)"
         HOMEPAGE_URL https://github.com/VKCOM/kphp)
 

common/common-tests.cmake

@@ -16,7 +16,8 @@ prepend(COMMON_TESTS_SOURCES ${COMMON_DIR}/
         smart_ptrs/tagged-ptr-test.cpp
         type_traits/list_of_types_test.cpp
         wrappers/span-test.cpp
-        wrappers/string_view-test.cpp)
+        wrappers/string_view-test.cpp
+        ucontext/ucontext-portable-test.cpp)
 
 prepare_cross_platform_libs(COMMON_TESTS_LIBS zstd)
 set(COMMON_TESTS_LIBS vk::common_src vk::net_src vk::binlog_src vk::unicode ${COMMON_TESTS_LIBS} ${EPOLL_SHIM_LIB} OpenSSL::Crypto z)

common/common.cmake

@@ -37,7 +37,14 @@ prepend(COMMON_TL_METHODS_SOURCES ${COMMON_DIR}/tl/methods/
 
 if (NOT CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
     prepend(COMMON_UCONTEXT_SOURCES ${COMMON_DIR}/ucontext/
-            ucontext-arm.cpp)
+            darwin/aarch64/context.cpp)
+else()
+    prepend(COMMON_UCONTEXT_SOURCES ${COMMON_DIR}/ucontext/
+            linux/x86_64/startcontext.S
+            linux/x86_64/getcontext.S
+            linux/x86_64/setcontext.S
+            linux/x86_64/swapcontext.S
+            linux/x86_64/makecontext.cpp)
 endif()
 
 set(COMMON_ALL_SOURCES

common/dl-utils-lite.cpp

@@ -178,6 +178,14 @@ void dl_allow_all_signals () {
   dl_passert (err != -1, "failed to allow all signals");
 }
 
+void dl_unblock_signal (int sig) {
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, sig);
+  int err = sigprocmask(SIG_UNBLOCK, &mask, nullptr);
+  dl_passert (err != -1, "failed to unblock signal");
+}
+
 static void runtime_handler (const int sig, siginfo_t *info __attribute__((unused)), void *ucontext) {
   fprintf (stderr, "%s caught, terminating program\n", strsignal(sig));
   crash_dump_write(static_cast<ucontext_t *>(ucontext));

common/dl-utils-lite.h

@@ -23,6 +23,7 @@ void dl_signal (int sig, void (*handler) (int));
 void dl_restore_signal_mask ();
 void dl_block_all_signals ();
 void dl_allow_all_signals ();
+void dl_unblock_signal (int sig);
 
 void dl_print_backtrace(void **trace, int trace_size);
 void dl_print_backtrace();

common/server/crash-dump.cpp

@@ -12,6 +12,7 @@
 
 #include "common/kprintf.h"
 #include "common/ucontext/ucontext-portable.h"
+#include <ucontext.h>
 
 struct crash_dump_buffer {
   char scratchpad[1024];

common/ucontext/ucontext-arm.cpp → common/ucontext/darwin/aarch64/context.cpp

@@ -1,15 +1,14 @@
 // Compiler for PHP (aka KPHP)
 // libucontext (c) https://github.com/kaniini/libucontext/tree/master (copied as third-party and slightly modified)
-// Copyright (c) 2023 LLC «V Kontakte»
+// Copyright (c) 2024 LLC «V Kontakte»
 // Distributed under the GPL v3 License, see LICENSE.notice.txt
 
-#include "common/ucontext/ucontext-arm.h"
-
 #include <cstdarg>
 #include <cstdint>
-#include <cstdio>
 #include <cstdlib>
 
+#include "common/ucontext/darwin/aarch64/context.h"
+
 enum { SP_OFFSET = 432, PC_OFFSET = 440, PSTATE_OFFSET = 448, FPSIMD_CONTEXT_OFFSET = 464 };
 
 #define STR(x) #x
@@ -31,6 +30,8 @@ static_assert(offsetof(libucontext_ucontext, uc_mcontext.sp) == SP_OFFSET, "SP_O
 static_assert(offsetof(libucontext_ucontext, uc_mcontext.pc) == PC_OFFSET, "PC_OFFSET is invalid");
 static_assert(offsetof(libucontext_ucontext, uc_mcontext.pstate) == PSTATE_OFFSET, "PSTATE_OFFSET is invalid");
 
+extern "C" int setcontext_portable(const libucontext_ucontext *);
+
 __attribute__((visibility("hidden"))) void libucontext_trampoline() {
   libucontext_ucontext *uc_link = nullptr;
 
@@ -40,10 +41,10 @@ __attribute__((visibility("hidden"))) void libucontext_trampoline() {
     exit(0);
   }
 
-  libucontext_setcontext(uc_link);
+  setcontext_portable(uc_link);
 }
 
-void libucontext_makecontext(libucontext_ucontext *ucp, void (*func)(), int argc, ...) {
+extern "C" void makecontext_portable(libucontext_ucontext *ucp, void (*func)(), int argc, ...) {
   unsigned long *sp;
   unsigned long *regp;
   va_list va;
@@ -73,27 +74,12 @@ void libucontext_makecontext(libucontext_ucontext *ucp, void (*func)(), int argc
   va_end(va);
 }
 
-asm(".global " NAME(libucontext_getcontext) ";\n"
+asm(".global " NAME(getcontext_portable) ";\n"
     ".align  2;\n"
-    NAME(libucontext_getcontext) ":\n"
+    NAME(getcontext_portable) ":\n"
     "str	xzr, [x0, #((184) + ((0) * (8)))]\n"       // #REG_OFFSET(0)
-    /* save GPRs */
-    "stp	x0, x1,   [x0, #((184) + ((0) * (8)))]\n"  // REG_OFFSET(0)
+    /* save x2 and x3 for reuse */
     "stp	x2, x3,   [x0, #((184) + ((2) * (8)))]\n"  // REG_OFFSET(2)
-    "stp	x4, x5,   [x0, #((184) + ((4) * (8)))]\n"  // REG_OFFSET(4)
-    "stp	x6, x7,   [x0, #((184) + ((6) * (8)))]\n"  // REG_OFFSET(6)
-    "stp	x8, x9,   [x0, #((184) + ((8) * (8)))]\n"  // REG_OFFSET(8)
-    "stp	x10, x11, [x0, #((184) + ((10) * (8)))]\n" // REG_OFFSET(10)
-    "stp	x12, x13, [x0, #((184) + ((12) * (8)))]\n" // REG_OFFSET(12)
-    "stp	x14, x15, [x0, #((184) + ((14) * (8)))]\n" // REG_OFFSET(14)
-    "stp	x16, x17, [x0, #((184) + ((16) * (8)))]\n" // REG_OFFSET(16)
-    "stp	x18, x19, [x0, #((184) + ((18) * (8)))]\n" // REG_OFFSET(18)
-    "stp	x20, x21, [x0, #((184) + ((20) * (8)))]\n" // REG_OFFSET(20)
-    "stp	x22, x23, [x0, #((184) + ((22) * (8)))]\n" // REG_OFFSET(22)
-    "stp	x24, x25, [x0, #((184) + ((24) * (8)))]\n" // REG_OFFSET(24)
-    "stp	x26, x27, [x0, #((184) + ((26) * (8)))]\n" // REG_OFFSET(26)
-    "stp	x28, x29, [x0, #((184) + ((28) * (8)))]\n" // REG_OFFSET(28)
-    "str	x30,      [x0, #((184) + ((30) * (8)))]\n" // REG_OFFSET(30)
     /* save current program counter in link register */
     "str	x30, [x0, #440]\n"                         // PC_OFFSET
     /* save current stack pointer */
@@ -106,12 +92,30 @@ asm(".global " NAME(libucontext_getcontext) ";\n"
     "stp q10, q11, [x2, #176]\n"
     "stp q12, q13, [x2, #208]\n"
     "stp q14, q15, [x2, #240]\n"
+    /* save GPRs and return value 0 */
+	  "mov	x2, x0\n"
     "mov	x0, #0\n"
+    "stp	x0, x1,   [x2, #((184) + ((0) * (8)))]\n"  // REG_OFFSET(0)
+    /* x2 and x3 have already been saved */
+    "stp	x4, x5,   [x2, #((184) + ((4) * (8)))]\n"  // REG_OFFSET(4)
+    "stp	x6, x7,   [x2, #((184) + ((6) * (8)))]\n"  // REG_OFFSET(6)
+    "stp	x8, x9,   [x2, #((184) + ((8) * (8)))]\n"  // REG_OFFSET(8)
+    "stp	x10, x11, [x2, #((184) + ((10) * (8)))]\n" // REG_OFFSET(10)
+    "stp	x12, x13, [x2, #((184) + ((12) * (8)))]\n" // REG_OFFSET(12)
+    "stp	x14, x15, [x2, #((184) + ((14) * (8)))]\n" // REG_OFFSET(14)
+    "stp	x16, x17, [x2, #((184) + ((16) * (8)))]\n" // REG_OFFSET(16)
+    "stp	x18, x19, [x2, #((184) + ((18) * (8)))]\n" // REG_OFFSET(18)
+    "stp	x20, x21, [x2, #((184) + ((20) * (8)))]\n" // REG_OFFSET(20)
+    "stp	x22, x23, [x2, #((184) + ((22) * (8)))]\n" // REG_OFFSET(22)
+    "stp	x24, x25, [x2, #((184) + ((24) * (8)))]\n" // REG_OFFSET(24)
+    "stp	x26, x27, [x2, #((184) + ((26) * (8)))]\n" // REG_OFFSET(26)
+    "stp	x28, x29, [x2, #((184) + ((28) * (8)))]\n" // REG_OFFSET(28)
+    "str	x30,      [x2, #((184) + ((30) * (8)))]\n" // REG_OFFSET(30)
     "ret\n");
 
-asm(".global " NAME(libucontext_setcontext) ";\n"
+asm(".global " NAME(setcontext_portable) ";\n"
     ".align  2;\n"
-    NAME(libucontext_setcontext) ":\n"
+    NAME(setcontext_portable) ":\n"
     /* restore GPRs */
     "ldp	x18, x19, [x0, #((184) + ((18) * (8)))]\n" // REG_OFFSET(18)
     "ldp	x20, x21, [x0, #((184) + ((20) * (8)))]\n" // REG_OFFSET(20)
@@ -138,9 +142,9 @@ asm(".global " NAME(libucontext_setcontext) ";\n"
     /* jump to new PC */
     "br	x16\n");
 
-asm(".global " NAME(libucontext_swapcontext) ";\n"
+asm(".global " NAME(swapcontext_portable) ";\n"
     ".align  2;\n"
-    NAME(libucontext_swapcontext) ":\n"
+    NAME(swapcontext_portable) ":\n"
     "str	xzr, [x0, #((184) + ((0) * (8)))]\n"       // REG_OFFSET(0)
 	  /* save GPRs */
 	  "stp	x2, x3,   [x0, #((184) + ((2) * (8)))]\n"  // REG_OFFSET(2)
@@ -175,7 +179,7 @@ asm(".global " NAME(libucontext_swapcontext) ";\n"
     "mov	x28, x30\n"
     /* move x1 to x0 and call setcontext */
     "mov	x0, x1\n"
-    "bl " NAME(libucontext_setcontext) "\n"
+    "bl " NAME(setcontext_portable) "\n"
 	  /* hmm, we came back here try to return */
 	  "mov	x30, x28\n"
     "ret\n");

common/ucontext/darwin/aarch64/context.h

@@ -0,0 +1,54 @@
+// Compiler for PHP (aka KPHP)
+// Copyright (c) 2018-2022 Ariadne Conill <[email protected]>
+// https://github.com/kaniini/libucontext/tree/master (copied as third-party and slightly modified)
+// Copyright (c) 2024 LLC «V Kontakte»
+// Distributed under the GPL v3 License, see LICENSE.notice.txt
+
+#pragma once
+
+#include <cstddef>
+
+struct libucontext_mcontext {
+  unsigned long fault_address;
+  unsigned long regs[29];
+  unsigned long fp, lr, sp, pc, pstate;
+  long double __reserved[256];
+};
+
+struct libucontext_stack {
+  void *ss_sp;
+  int ss_flags;
+  size_t ss_size;
+};
+
+struct libucontext_ucontext {
+  unsigned long uc_flags;
+  struct libucontext_ucontext *uc_link;
+  libucontext_stack uc_stack;
+  unsigned char __pad[136];
+  libucontext_mcontext uc_mcontext;
+};
+
+inline constexpr void *get_context_stack_ptr_portable(const libucontext_ucontext &ctx) noexcept {
+  return ctx.uc_stack.ss_sp;
+}
+
+inline constexpr size_t get_context_stack_size_portable(const libucontext_ucontext &ctx) noexcept {
+  return ctx.uc_stack.ss_size;
+}
+
+inline constexpr void set_context_stack_ptr_portable(libucontext_ucontext &ctx, void *sp) noexcept {
+  ctx.uc_stack.ss_sp = sp;
+}
+
+inline constexpr void set_context_stack_size_portable(libucontext_ucontext &ctx, size_t size) noexcept {
+  ctx.uc_stack.ss_size = size;
+}
+
+inline constexpr void set_context_link_portable(libucontext_ucontext &ctx, libucontext_ucontext *link) noexcept {
+  ctx.uc_link = link;
+}
+
+inline void *get_context_stack_base_ptr_portable(const libucontext_ucontext &ctx) noexcept {
+  return reinterpret_cast<void *>(ctx.uc_mcontext.fp);
+}

common/ucontext/darwin/x86_64/context.h

@@ -0,0 +1,29 @@
+// Compiler for PHP (aka KPHP)
+// Copyright (c) 2024 LLC «V Kontakte»
+// Distributed under the GPL v3 License, see LICENSE.notice.txt
+
+#include <ucontext.h>
+
+inline constexpr void *get_context_stack_ptr_portable(const ucontext_t &ctx) noexcept {
+  return ctx.uc_stack.ss_sp;
+}
+
+inline constexpr size_t get_context_stack_size_portable(const ucontext_t &ctx) noexcept {
+  return ctx.uc_stack.ss_size;
+}
+
+inline constexpr void set_context_stack_ptr_portable(ucontext_t &ctx, void *sp) noexcept {
+  ctx.uc_stack.ss_sp = sp;
+}
+
+inline constexpr void set_context_stack_size_portable(ucontext_t &ctx, size_t size) noexcept {
+  ctx.uc_stack.ss_size = size;
+}
+
+inline constexpr void set_context_link_portable(ucontext_t &ctx, ucontext_t *link) noexcept {
+  ctx.uc_link = link;
+}
+
+inline void *get_context_stack_base_ptr_portable(const ucontext_t &ctx) noexcept {
+  return reinterpret_cast<void *>(ctx.uc_mcontext->__ss.__rbp);
+}

common/ucontext/linux/aarch64/context.h

@@ -0,0 +1,30 @@
+// Compiler for PHP (aka KPHP)
+// Copyright (c) 2024 LLC «V Kontakte»
+// Distributed under the GPL v3 License, see LICENSE.notice.txt
+
+#include <ucontext.h>
+
+inline constexpr void *get_context_stack_ptr_portable(const ucontext_t &ctx) noexcept {
+  return ctx.uc_stack.ss_sp;
+}
+
+inline constexpr size_t get_context_stack_size_portable(const ucontext_t &ctx) noexcept {
+  return ctx.uc_stack.ss_size;
+}
+
+inline constexpr void set_context_stack_ptr_portable(ucontext_t &ctx, void *sp) noexcept {
+  ctx.uc_stack.ss_sp = sp;
+}
+
+inline constexpr void set_context_stack_size_portable(ucontext_t &ctx, size_t size) noexcept {
+  ctx.uc_stack.ss_size = size;
+}
+
+inline constexpr void set_context_link_portable(ucontext_t &ctx, ucontext_t *link) noexcept {
+  ctx.uc_link = link;
+}
+
+inline void *get_context_stack_base_ptr_portable(const ucontext_t &ctx) noexcept {
+  // 29 -- Frame Pointer, based on AArch64 spec
+  return reinterpret_cast<void *>(ctx.uc_mcontext.regs[29]);
+}