Changeset ead174a

Timestamp:

Nov 11, 2020, 5:43:27 PM (4 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

ad4832f1

Parents:

b0b1e15

Message:

Fixed implementation of TLS protection for aarch64

File:

• libcfa/src/concurrency/preemption.cfa (modified) (15 diffs)

libcfa/src/concurrency/preemption.cfa

@@ -215 +215 @@
 // available.
 
+//-----------------------------------------------------------------------------
+// Some assembly required
+#define __cfaasm_label(label, when) when: asm volatile goto(".global __cfaasm_" #label "_" #when "\n" "__cfaasm_" #label "_" #when ":":::"memory":when)
+
 //----------
 // special case for preemption since used often
@@ -220 +224 @@
         // create a assembler label before
         // marked as clobber all to avoid movement
-        asm volatile("__cfaasm_check_before:":::"memory");
+        __cfaasm_label(check, before);
 
         // access tls as normal
@@ -227 +231 @@
         // create a assembler label after
         // marked as clobber all to avoid movement
-        asm volatile("__cfaasm_check_after:":::"memory");
+        __cfaasm_label(check, after);
         return enabled;
 }
@@ -246 +250 @@
 uintptr_t __cfatls_get( unsigned long int offset ) __attribute__((__noinline__)); //no inline to avoid problems
 uintptr_t __cfatls_get( unsigned long int offset ) {
-        // __cfaasm_get.before = ({ void * value; asm("movq $__cfaasm_get_before, %[v]\n\t" : [v]"=r"(value) ); value; });
-        // __cfaasm_get.after  = ({ void * value; asm("movq $__cfaasm_get_after , %[v]\n\t" : [v]"=r"(value) ); value; });
         // create a assembler label before
         // marked as clobber all to avoid movement
-        asm volatile("__cfaasm_get_before:":::"memory");
+        __cfaasm_label(get, before);
 
         // access tls as normal (except for pointer arithmetic)
@@ -257 +259 @@
         // create a assembler label after
         // marked as clobber all to avoid movement
-        asm volatile("__cfaasm_get_after:":::"memory");
+        __cfaasm_label(get, after);
         return val;
 }
@@ -266 +268 @@
                 // create a assembler label before
                 // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_dsable_before:":::"memory");
+                __cfaasm_label(dsable, before);
 
                 with( __cfaabi_tls.preemption_state ) {
@@ -288 +290 @@
                 // create a assembler label after
                 // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_dsable_after:":::"memory");
+                __cfaasm_label(dsable, after);
+
         }
 
@@ -294 +297 @@
         // If counter reaches 0, execute any pending __cfactx_switch
         void enable_interrupts( __cfaabi_dbg_ctx_param ) {
-                // create a assembler label before
-                // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_enble_before:":::"memory");
-
-                processor   * proc = __cfaabi_tls.this_processor; // Cache the processor now since interrupts can start happening after the atomic store
+                // Cache the processor now since interrupts can start happening after the atomic store
+                processor   * proc = __cfaabi_tls.this_processor;
                 /* paranoid */ verify( proc );
 
@@ -304 +304 @@
                         unsigned short prev = disable_count;
                         disable_count -= 1;
-                        verify( prev != 0u );                     // If this triggers someone is enabled already enabled interruptsverify( prev != 0u );
+
+                        // If this triggers someone is enabled already enabled interruptsverify( prev != 0u );
+                        /* paranoid */ verify( prev != 0u );
 
                         // Check if we need to prempt the thread because an interrupt was missed
                         if( prev == 1 ) {
                                 #if GCC_VERSION > 50000
-                                static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free");
+                                        static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free");
                                 #endif
 
@@ -328 +330 @@
                 // For debugging purposes : keep track of the last person to enable the interrupts
                 __cfaabi_dbg_debug_do( proc->last_enable = caller; )
-
-                // create a assembler label after
-                // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_enble_after:":::"memory");
         }
 
@@ -337 +335 @@
         // Don't execute any pending __cfactx_switch even if counter reaches 0
         void enable_interrupts_noPoll() {
-                // create a assembler label before
-                // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_nopoll_before:":::"memory");
-
                 unsigned short prev = __cfaabi_tls.preemption_state.disable_count;
                 __cfaabi_tls.preemption_state.disable_count -= 1;
-                verifyf( prev != 0u, "Incremented from %u\n", prev );                     // If this triggers someone is enabled already enabled interrupts
+                // If this triggers someone is enabled already enabled interrupts
+                /* paranoid */ verifyf( prev != 0u, "Incremented from %u\n", prev );
                 if( prev == 1 ) {
                         #if GCC_VERSION > 50000
-                        static_assert(__atomic_always_lock_free(sizeof(__cfaabi_tls.preemption_state.enabled), &__cfaabi_tls.preemption_state.enabled), "Must be lock-free");
+                                static_assert(__atomic_always_lock_free(sizeof(__cfaabi_tls.preemption_state.enabled), &__cfaabi_tls.preemption_state.enabled), "Must be lock-free");
                         #endif
                         // Set enabled flag to true
@@ -356 +351 @@
                         __atomic_signal_fence(__ATOMIC_RELEASE);
                 }
-
-                // create a assembler label after
-                // marked as clobber all to avoid movement
-                asm volatile("__cfaasm_nopoll_after:":::"memory");
-        }
-}
+        }
+}
+
+#undef __cfaasm_label
 
 // sigprocmask wrapper : unblock a single signal
@@ -446 +439 @@
 #elif defined( __aarch64__ )
         #ifdef __PIC__
-                #define RELOC_TAG "@PLT"
-        #else
-                #define RELOC_TAG ""
-        #endif
-        #define __cfaasm_label( label ) \
+                // Note that this works only for gcc
+                #define __cfaasm_label( label ) static struct asm_region label = \
                 ({ \
                         struct asm_region region; \
                         asm( \
-                                "mov %[vb], __cfaasm_" #label "_before@GOTPCREL(%%rip)"  "\n\t" \
-                                "mov %[va], __cfaasm_" #label "_after@GOTPCREL(%%rip)"   "\n\t" \
+                                "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 ) static 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
@@ -473 +480 @@
         __cfaasm_label( check  );
         __cfaasm_label( dsable );
-        __cfaasm_label( enble );
-        __cfaasm_label( nopoll );
 
         // Check if preemption is safe
@@ -481 +486 @@
         if( __cfaasm_in( ip, check  ) ) { ready = false; goto EXIT; };
         if( __cfaasm_in( ip, dsable ) ) { ready = false; goto EXIT; };
-        if( __cfaasm_in( ip, enble  ) ) { ready = false; goto EXIT; };
-        if( __cfaasm_in( ip, nopoll ) ) { 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; };