diff options
| -rw-r--r-- | rts/Linker.c | 37 |
1 files changed, 27 insertions, 10 deletions
diff --git a/rts/Linker.c b/rts/Linker.c index 2641a677be..d297f3a8ff 100644 --- a/rts/Linker.c +++ b/rts/Linker.c @@ -450,16 +450,6 @@ initLinker_ (int retain_cafs) IF_DEBUG(linker, debugBelch("initLinker: inserting rts symbol %s, %p\n", sym->lbl, sym->addr)); } - /* GCC defines a special symbol __dso_handle which is resolved to NULL if - referenced from a statically linked module. We need to mimic this, but - we cannot use NULL because we use it to mean nonexistent symbols. So we - use an arbitrary (hopefully unique) address here. - */ - if (! ghciInsertSymbolTable(WSTR("(GHCi special symbols)"), - symhash, "__dso_handle", (void *)0x12345687, HS_BOOL_FALSE, NULL)) { - barf("ghciInsertSymbolTable failed"); - } - // Redirect newCAF to newRetainedCAF if retain_cafs is true. if (! ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"), symhash, MAYBE_LEADING_UNDERSCORE_STR("newCAF"), @@ -865,6 +855,17 @@ SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent) ASSERT(symhash != NULL); RtsSymbolInfo *pinfo; + /* See Note [Resolving __dso_handle] */ + if (strcmp(lbl, "__dso_handle") == 0) { + if (dependent) { + return dependent->image; + } else { + // In the case that we don't know which object the reference lives + // in we return a random symbol from the executable image. + return &lookupDependentSymbol; + } + } + if (!ghciLookupSymbolInfo(symhash, lbl, &pinfo)) { IF_DEBUG(linker, debugBelch("lookupSymbol: symbol '%s' not found, trying dlsym\n", lbl)); @@ -900,6 +901,22 @@ SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent) } #endif /* OBJFORMAT_PEi386 */ +/* Note [Resolving __dso_handle] + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * This symbol, which is defined by the C++ ABI, would typically be defined by + * the system's dynamic linker to act as a "handle", identifying a particular + * loaded dynamic object to the C++ standard library for the purpose of running + * destructors on unload. Here we behave the same way that the dynamic linker + * would, using some address (here the start address) of the loaded object as + * its handle. + * + * Note that references to __dso_handle may be relocated using + * relocations of bounded displacement and therefore __dso_handle must not be + * too far from the loaded object's code (hence using its start address). + * + * See #20493. + */ + /* * Load and relocate the object code for a symbol as necessary. * Symbol name only used for diagnostics output. |