Changeset 23a08aa0 for libcfa/src/concurrency/preemption.cfa

Timestamp:

Sep 19, 2022, 8:11:02 PM (3 years ago)

Author:

Peter A. Buhr <pabuhr@…>

Branches:

ADT, ast-experimental, master, pthread-emulation

Children:

aa9f215

Parents:

ebf8ca5 (diff), ae1d151 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

fix merge conflict

File:

• libcfa/src/concurrency/preemption.cfa (modified) (8 diffs)

libcfa/src/concurrency/preemption.cfa

@@ -238 +238 @@
 //----------
 // special case for preemption since used often
-__attribute__((optimize("no-reorder-blocks"))) bool __preemption_enabled() libcfa_public {
+__attribute__((optimize("no-reorder-blocks"))) bool __preemption_enabled() libcfa_nopreempt libcfa_public {
         // create a assembler label before
         // marked as clobber all to avoid movement
@@ -272 +272 @@
 }
 
+extern "C" {
+        __attribute__((visibility("hidden"))) extern void * const __start_cfatext_nopreempt;
+        __attribute__((visibility("hidden"))) extern void * const __stop_cfatext_nopreempt;
+
+        extern const __cfa_nopreempt_region __libcfa_nopreempt;
+        __attribute__((visibility("protected"))) const __cfa_nopreempt_region __libcfathrd_nopreempt @= {
+                (void * const)&__start_cfatext_nopreempt,
+                (void * const)&__stop_cfatext_nopreempt
+        };
+}
+
+static inline bool __cfaabi_in( void * const ip, const struct __cfa_nopreempt_region & const region ) {
+        return ip >= region.start && ip <= region.stop;
+}
+
 
 //----------
 // Get data from the TLS block
 // struct asm_region __cfaasm_get;
-uintptr_t __cfatls_get( unsigned long int offset ) __attribute__((__noinline__, visibility("default"))); //no inline to avoid problems
+uintptr_t __cfatls_get( unsigned long int offset ) libcfa_nopreempt libcfa_public; //no inline to avoid problems
 uintptr_t __cfatls_get( unsigned long int offset ) {
         // create a assembler label before
@@ -295 +310 @@
 extern "C" {
         // Disable interrupts by incrementing the counter
-        __attribute__((__noinline__, visibility("default"))) void disable_interrupts() libcfa_public {
+        void disable_interrupts() libcfa_nopreempt libcfa_public {
                 // create a assembler label before
                 // marked as clobber all to avoid movement
@@ -326 +341 @@
         // Enable interrupts by decrementing the counter
         // If counter reaches 0, execute any pending __cfactx_switch
-        void enable_interrupts( bool poll ) libcfa_public {
+        void enable_interrupts( bool poll ) libcfa_nopreempt libcfa_public {
                 // Cache the processor now since interrupts can start happening after the atomic store
                 processor   * proc = __cfaabi_tls.this_processor;
@@ -358 +373 @@
                 }
         }
+
+        // Check whether or not there is pending preemption
+        // force_yield( __POLL_PREEMPTION ) if appropriate
+        // return true if the thread was in an interruptable state
+        // i.e. on a real processor and not in the kernel
+        // (can return true even if no preemption was pending)
+        bool poll_interrupts() libcfa_public {
+                // Cache the processor now since interrupts can start happening after the atomic store
+                processor   * proc = publicTLS_get( this_processor );
+                if ( ! proc ) return false;
+                if ( ! __preemption_enabled() ) return false;
+
+                with( __cfaabi_tls.preemption_state ){
+                        // Signal the compiler that a fence is needed but only for signal handlers
+                        __atomic_signal_fence(__ATOMIC_RELEASE);
+                        if( proc->pending_preemption ) {
+                                proc->pending_preemption = false;
+                                force_yield( __POLL_PREEMPTION );
+                        }
+                }
+
+                return true;
+        }
 }
 
@@ -463 +501 @@
 
 //-----------------------------------------------------------------------------
-// Some assembly required
-#if defined( __i386 )
-        #ifdef __PIC__
-                #define RELOC_PRELUDE( label ) \
-                        "calll   .Lcfaasm_prelude_" #label "$pb\n\t" \
-                        ".Lcfaasm_prelude_" #label "$pb:\n\t" \
-                        "popl    %%eax\n\t" \
-                        ".Lcfaasm_prelude_" #label "_end:\n\t" \
-                        "addl    $_GLOBAL_OFFSET_TABLE_+(.Lcfaasm_prelude_" #label "_end-.Lcfaasm_prelude_" #label "$pb), %%eax\n\t"
-                #define RELOC_PREFIX ""
-                #define RELOC_SUFFIX "@GOT(%%eax)"
-        #else
-                #define RELOC_PREFIX "$"
-                #define RELOC_SUFFIX ""
-        #endif
-        #define __cfaasm_label( label ) struct asm_region label = \
-                ({ \
-                        struct asm_region region; \
-                        asm( \
-                                RELOC_PRELUDE( label ) \
-                                "movl " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \
-                                "movl " RELOC_PREFIX "__cfaasm_" #label "_after"  RELOC_SUFFIX ", %[va]\n\t" \
-                                 : [vb]"=r"(region.before), [va]"=r"(region.after) \
-                        ); \
-                        region; \
-                });
-#elif defined( __x86_64 )
-        #ifdef __PIC__
-                #define RELOC_PREFIX ""
-                #define RELOC_SUFFIX "@GOTPCREL(%%rip)"
-        #else
-                #define RELOC_PREFIX "$"
-                #define RELOC_SUFFIX ""
-        #endif
-        #define __cfaasm_label( label ) struct asm_region label = \
-                ({ \
-                        struct asm_region region; \
-                        asm( \
-                                "movq " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \
-                                "movq " RELOC_PREFIX "__cfaasm_" #label "_after"  RELOC_SUFFIX ", %[va]\n\t" \
-                                 : [vb]"=r"(region.before), [va]"=r"(region.after) \
-                        ); \
-                        region; \
-                });
-#elif defined( __aarch64__ )
-        #ifdef __PIC__
-                // Note that this works only for gcc
-                #define __cfaasm_label( label ) struct asm_region label = \
-                ({ \
-                        struct asm_region region; \
-                        asm( \
-                                "adrp %[vb], _GLOBAL_OFFSET_TABLE_"                              "\n\t" \
-                                "ldr  %[vb], [%[vb], #:gotpage_lo15:__cfaasm_" #label "_before]" "\n\t" \
-                                "adrp %[va], _GLOBAL_OFFSET_TABLE_"                              "\n\t" \
-                                "ldr  %[va], [%[va], #:gotpage_lo15:__cfaasm_" #label "_after]"  "\n\t" \
-                                 : [vb]"=r"(region.before), [va]"=r"(region.after) \
-                        ); \
-                        region; \
-                });
-        #else
-                #error this is not the right thing to do
-                /*
-                #define __cfaasm_label( label ) struct asm_region label = \
-                ({ \
-                        struct asm_region region; \
-                        asm( \
-                                "adrp %[vb], __cfaasm_" #label "_before"              "\n\t" \
-                                "add  %[vb], %[vb], :lo12:__cfaasm_" #label "_before" "\n\t" \
-                                "adrp %[va], :got:__cfaasm_" #label "_after"          "\n\t" \
-                                "add  %[va], %[va], :lo12:__cfaasm_" #label "_after"  "\n\t" \
-                                 : [vb]"=r"(region.before), [va]"=r"(region.after) \
-                        ); \
-                        region; \
-                });
-                */
-        #endif
-#else
-        #error unknown hardware architecture
-#endif
-
 // KERNEL ONLY
 // Check if a __cfactx_switch signal handler shoud defer
@@ -548 +506 @@
 // If false : preemption is unsafe and marked as pending
 static inline bool preemption_ready( void * ip ) {
-        // Get all the region for which it is not safe to preempt
-        __cfaasm_label( get    );
-        __cfaasm_label( check  );
-        __cfaasm_label( dsable );
-        // __cfaasm_label( debug  );
-
         // Check if preemption is safe
         bool ready = true;
-        if( __cfaasm_in( ip, get    ) ) { ready = false; goto EXIT; };
-        if( __cfaasm_in( ip, check  ) ) { ready = false; goto EXIT; };
-        if( __cfaasm_in( ip, dsable ) ) { ready = false; goto EXIT; };
-        // if( __cfaasm_in( ip, debug  ) ) { ready = false; goto EXIT; };
+        if( __cfaabi_in( ip, __libcfa_nopreempt ) ) { ready = false; goto EXIT; };
+        if( __cfaabi_in( ip, __libcfathrd_nopreempt ) ) { ready = false; goto EXIT; };
+
         if( !__cfaabi_tls.preemption_state.enabled) { ready = false; goto EXIT; };
         if( __cfaabi_tls.preemption_state.in_progress ) { ready = false; goto EXIT; };
@@ -643 +594 @@
 // Kernel Signal Handlers
 //=============================================================================================
-__cfaabi_dbg_debug_do( static thread_local void * last_interrupt = 0; )
+__cfaabi_dbg_debug_do( static __thread void * last_interrupt = 0; )
 
 // Context switch signal handler