i386: Support thread-local storage (TLS)

Update #2468.

3 files changed, 43 insertions, 7 deletions

diff --git a/cpukit/score/cpu/i386/cpu.c b/cpukit/score/cpu/i386/cpu.c
index 804afb1647..c9434f7c86 100644
--- a/cpukit/score/cpu/i386/cpu.c
+++ b/cpukit/score/cpu/i386/cpu.c
@@ -24,6 +24,7 @@
 #include <rtems/score/types.h>
 #include <rtems/score/isr.h>
 #include <rtems/score/idtr.h>
+#include <rtems/score/tls.h>
 
 #include <rtems/bspIo.h>
 #include <rtems/score/percpu.h>
@@ -43,6 +44,12 @@ I386_ASSERT_OFFSET(ebx, EBX);
 I386_ASSERT_OFFSET(esi, ESI);
 I386_ASSERT_OFFSET(edi, EDI);
 
+RTEMS_STATIC_ASSERT(
+  offsetof(Context_Control, gs)
+    == I386_CONTEXT_CONTROL_GS_0_OFFSET,
+  Context_Control_gs_0
+);
+
 #ifdef RTEMS_SMP
   I386_ASSERT_OFFSET(is_executing, IS_EXECUTING);
 #endif
@@ -153,6 +160,7 @@ void _CPU_Context_Initialize(
 )
 {
   uint32_t _stack;
+  uint32_t tcb;
 
   (void) is_fp; /* avoid warning for being unused */
 
@@ -168,6 +176,23 @@ void _CPU_Context_Initialize(
   *((proc_ptr *)(_stack)) = (_entry_point);
   the_context->ebp     = (void *) 0;
   the_context->esp     = (void *) _stack;
+
+  if ( tls_area != NULL ) {
+    tcb = (uint32_t) _TLS_TCB_after_TLS_block_initialize( tls_area );
+  } else {
+    tcb = 0;
+  }
+
+  the_context->gs.limit_15_0 = 0xffff;
+  the_context->gs.base_address_15_0 = (tcb >> 0) & 0xffff;
+  the_context->gs.type = 0x2;
+  the_context->gs.descriptor_type = 0x1;
+  the_context->gs.limit_19_16 = 0xf;
+  the_context->gs.present = 0x1;
+  the_context->gs.operation_size = 0x1;
+  the_context->gs.granularity = 0x1;
+  the_context->gs.base_address_23_16 = (tcb >> 16) & 0xff;
+  the_context->gs.base_address_31_24 = (tcb >> 24) & 0xff;
 }
 
 uint32_t   _CPU_ISR_Get_level( void )
diff --git a/cpukit/score/cpu/i386/cpu_asm.S b/cpukit/score/cpu/i386/cpu_asm.S
index 45079a65b8..6b609ab4ce 100644
--- a/cpukit/score/cpu/i386/cpu_asm.S
+++ b/cpukit/score/cpu/i386/cpu_asm.S
@@ -32,6 +32,8 @@
 .set REG_EBX,     I386_CONTEXT_CONTROL_EBX_OFFSET
 .set REG_ESI,     I386_CONTEXT_CONTROL_ESI_OFFSET
 .set REG_EDI,     I386_CONTEXT_CONTROL_EDI_OFFSET
+.set REG_GS_0,    I386_CONTEXT_CONTROL_GS_0_OFFSET
+.set REG_GS_1,    I386_CONTEXT_CONTROL_GS_1_OFFSET
 
         BEGIN_CODE
 
@@ -83,6 +85,12 @@ restore:
         movl      REG_EBX(eax),ebx         /* restore ebx */
         movl      REG_ESI(eax),esi         /* restore source register */
         movl      REG_EDI(eax),edi         /* restore destination register */
+        movl      REG_GS_0(eax), ecx       /* restore gs segment */
+        movl      REG_GS_1(eax), edx
+        movl      ecx, _Global_descriptor_table + 24
+        movl      edx, _Global_descriptor_table + 28
+        movl      $24, ecx
+        mov       ecx, gs
         ret
 
 /*
diff --git a/cpukit/score/cpu/i386/rtems/score/cpu.h b/cpukit/score/cpu/i386/rtems/score/cpu.h
index 64f049ed0b..f78149c24b 100644
--- a/cpukit/score/cpu/i386/rtems/score/cpu.h
+++ b/cpukit/score/cpu/i386/rtems/score/cpu.h
@@ -122,9 +122,11 @@ extern "C" {
 #define I386_CONTEXT_CONTROL_EBX_OFFSET 12
 #define I386_CONTEXT_CONTROL_ESI_OFFSET 16
 #define I386_CONTEXT_CONTROL_EDI_OFFSET 20
+#define I386_CONTEXT_CONTROL_GS_0_OFFSET 24
+#define I386_CONTEXT_CONTROL_GS_1_OFFSET 28
 
 #ifdef RTEMS_SMP
-  #define I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET 24
+  #define I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET 32
 #endif
 
 /* structures */
@@ -136,12 +138,13 @@ extern "C" {
  */
 
 typedef struct {
-  uint32_t    eflags;   /* extended flags register                   */
-  void       *esp;      /* extended stack pointer register           */
-  void       *ebp;      /* extended base pointer register            */
-  uint32_t    ebx;      /* extended bx register                      */
-  uint32_t    esi;      /* extended source index register            */
-  uint32_t    edi;      /* extended destination index flags register */
+  uint32_t    eflags;     /* extended flags register                   */
+  void       *esp;        /* extended stack pointer register           */
+  void       *ebp;        /* extended base pointer register            */
+  uint32_t    ebx;        /* extended bx register                      */
+  uint32_t    esi;        /* extended source index register            */
+  uint32_t    edi;        /* extended destination index flags register */
+  segment_descriptors gs; /* gs segment descriptor                     */
 #ifdef RTEMS_SMP
   volatile bool is_executing;
 #endif