[fuchsia] Add fp registers to x86 context

This lays groundwork for floating point registers to also be included in
RISC-V CPU context.

Bug: fuchsia:5496

Tested: `fx test crashpad`
Change-Id: I6230f146f955ac27f053f670f7f45dfff3560d02
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4594586
Reviewed-by: Mark Mentovai <mark@chromium.org>

snapshot/fuchsia/cpu_context_fuchsia.cc

@@ -21,8 +21,9 @@ namespace internal {
 
 #if defined(ARCH_CPU_X86_64)
 
-void InitializeCPUContextX86_64_NoFloatingPoint(
+void InitializeCPUContextX86_64(
     const zx_thread_state_general_regs_t& thread_context,
+    const zx_thread_state_fp_regs_t& float_context,
     CPUContextX86_64* context) {
   memset(context, 0, sizeof(*context));
   context->rax = thread_context.rax;
@@ -43,6 +44,19 @@ void InitializeCPUContextX86_64_NoFloatingPoint(
   context->r15 = thread_context.r15;
   context->rip = thread_context.rip;
   context->rflags = thread_context.rflags;
+
+  context->fxsave.fcw = float_context.fcw;
+  context->fxsave.fsw = float_context.fsw;
+  context->fxsave.ftw = float_context.ftw;
+  context->fxsave.fop = float_context.fop;
+  context->fxsave.fpu_ip_64 = float_context.fip;
+  context->fxsave.fpu_dp_64 = float_context.fdp;
+
+  for (size_t i = 0; i < std::size(float_context.st); ++i) {
+    memcpy(&context->fxsave.st_mm[i],
+           &float_context.st[i],
+           sizeof(float_context.st[i]));
+  }
 }
 
 #elif defined(ARCH_CPU_ARM64)

snapshot/fuchsia/cpu_context_fuchsia.h

@@ -29,13 +29,14 @@ namespace internal {
 //! \brief Initializes a CPUContextX86_64 structure from native context
 //!     structures on Fuchsia.
 //!
-//! Floating point registers are currently initialized to zero.
 //! Segment registers are currently initialized to zero.
 //!
 //! \param[in] thread_context The native thread context.
+//! \param[in] float_context The native floating point context.
 //! \param[out] context The CPUContextX86_64 structure to initialize.
-void InitializeCPUContextX86_64_NoFloatingPoint(
+void InitializeCPUContextX86_64(
     const zx_thread_state_general_regs_t& thread_context,
+    const zx_thread_state_fp_regs_t& float_context,
     CPUContextX86_64* context);
 
 #endif  // ARCH_CPU_X86_64 || DOXYGEN

snapshot/fuchsia/exception_snapshot_fuchsia.cc

@@ -70,9 +70,9 @@ bool ExceptionSnapshotFuchsia::Initialize(
 #if defined(ARCH_CPU_X86_64)
   context_.architecture = kCPUArchitectureX86_64;
   context_.x86_64 = &context_arch_;
-  // TODO(fxbug.dev/5496): Add float context once saved in |t|.
+  // TODO(fxbug.dev/5496): Add vector context.
-  InitializeCPUContextX86_64_NoFloatingPoint(t->general_registers,
+  InitializeCPUContextX86_64(
-                                             context_.x86_64);
+      t->general_registers, t->fp_registers, context_.x86_64);
 #elif defined(ARCH_CPU_ARM64)
   context_.architecture = kCPUArchitectureARM64;
   context_.arm64 = &context_arch_;

snapshot/fuchsia/process_reader_fuchsia.cc

@@ -346,6 +346,16 @@ void ProcessReaderFuchsia::InitializeThreads() {
         }
       }
 
+      zx_thread_state_fp_regs_t fp_regs;
+      status = thread_handles[i].read_state(
+          ZX_THREAD_STATE_FP_REGS, &fp_regs, sizeof(fp_regs));
+      if (status != ZX_OK) {
+        ZX_LOG(WARNING, status)
+            << "zx_thread_read_state(ZX_THREAD_STATE_FP_REGS)";
+      } else {
+        thread.fp_registers = fp_regs;
+      }
+
       zx_thread_state_vector_regs_t vector_regs;
       status = thread_handles[i].read_state(
           ZX_THREAD_STATE_VECTOR_REGS, &vector_regs, sizeof(vector_regs));

snapshot/fuchsia/process_reader_fuchsia.h

@@ -76,6 +76,10 @@ class ProcessReaderFuchsia {
     //!     returned by `zx_thread_read_state()`.
     zx_thread_state_general_regs_t general_registers = {};
 
+    //! \brief The raw architecture-specific `zx_thread_state_fp_regs_t` as
+    //!     returned by `zx_thread_read_state()`.
+    zx_thread_state_fp_regs_t fp_registers = {};
+
     //! \brief The raw architecture-specific `zx_thread_state_vector_regs_t` as
     //!     returned by `zx_thread_read_state()`.
     zx_thread_state_vector_regs_t vector_registers = {};

snapshot/fuchsia/thread_snapshot_fuchsia.cc

@@ -40,9 +40,9 @@ bool ThreadSnapshotFuchsia::Initialize(
 #if defined(ARCH_CPU_X86_64)
   context_.architecture = kCPUArchitectureX86_64;
   context_.x86_64 = &context_arch_;
-  // TODO(fuchsia/DX-642): Add float context once saved in |thread|.
+  // TODO(fxbug.dev/5496): Add vector context.
-  InitializeCPUContextX86_64_NoFloatingPoint(thread.general_registers,
+  InitializeCPUContextX86_64(
-                                             context_.x86_64);
+      thread.general_registers, thread.fp_registers, context_.x86_64);
 #elif defined(ARCH_CPU_ARM64)
   context_.architecture = kCPUArchitectureARM64;
   context_.arm64 = &context_arch_;