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Commit 41fb6366 authored by aljee@hyper.cx's avatar aljee@hyper.cx Committed by Austin Seipp
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ghci: add support for ELF weak symbols 

Signed-off-by: default avatarAustin Seipp <austin@well-typed.com>
parent 736ed655
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Showing with 77 additions and 23 deletions
rts/Linker.c
View file @ 41fb6366
......@@ -137,7 +137,13 @@
#include <sys/tls.h>
#endif
/* Hash table mapping symbol names to Symbol */
typedef struct _RtsSymbolInfo {
void *value;
const ObjectCode *owner;
HsBool weak;
} RtsSymbolInfo;
/* Hash table mapping symbol names to RtsSymbolInfo */
static /*Str*/HashTable *symhash;
/* List of currently loaded objects */
......@@ -1464,15 +1470,31 @@ static RtsSymbolVal rtsSyms[] = {
* Insert symbols into hash tables, checking for duplicates.
*/
static void ghciInsertStrHashTable ( pathchar* obj_name,
HashTable *table,
char* key,
void *data
)
static void ghciInsertSymbolTable(
pathchar* obj_name,
HashTable *table,
char* key,
void *data,
HsBool weak,
ObjectCode *owner)
{
if (lookupHashTable(table, (StgWord)key) == NULL)
RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
if (!pinfo) /* new entry */
{
pinfo = stgMallocBytes(sizeof (*pinfo), "ghciInsertToSymbolTable");
pinfo->value = data;
pinfo->owner = owner;
pinfo->weak = weak;
insertStrHashTable(table, key, pinfo);
return;
} else if ((!pinfo->weak || pinfo->value) && weak) {
return; /* duplicate weak symbol, throw it away */
} else if (pinfo->weak) /* weak symbol is in the table */
{
insertStrHashTable(table, (StgWord)key, data);
/* override the weak definition with the non-weak one */
pinfo->value = data;
pinfo->owner = owner;
pinfo->weak = HS_BOOL_FALSE;
return;
}
debugBelch(
......@@ -1493,6 +1515,32 @@ static void ghciInsertStrHashTable ( pathchar* obj_name,
);
stg_exit(1);
}
static HsBool ghciLookupSymbolTable(HashTable *table,
const char *key, void **result)
{
RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
if (!pinfo) {
*result = NULL;
return HS_BOOL_FALSE;
}
if (pinfo->weak)
IF_DEBUG(linker, debugBelch("lookup: promoting %s\n", key));
/* Once it's looked up, it can no longer be overridden */
pinfo->weak = HS_BOOL_FALSE;
*result = pinfo->value;
return HS_BOOL_TRUE;
}
static void ghciRemoveSymbolTable(HashTable *table, const char *key,
ObjectCode *owner)
{
RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
if (!pinfo || owner != pinfo->owner) return;
removeStrHashTable(table, key, NULL);
stgFree(pinfo);
}
/* -----------------------------------------------------------------------------
* initialize the object linker
*/
......@@ -1539,8 +1587,8 @@ initLinker( void )
/* populate the symbol table with stuff from the RTS */
for (sym = rtsSyms; sym->lbl != NULL; sym++) {
ghciInsertStrHashTable(WSTR("(GHCi built-in symbols)"),
symhash, sym->lbl, sym->addr);
ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"),
symhash, sym->lbl, sym->addr, HS_BOOL_FALSE, NULL);
IF_DEBUG(linker, debugBelch("initLinker: inserting rts symbol %s, %p\n", sym->lbl, sym->addr));
}
# if defined(OBJFORMAT_MACHO) && defined(powerpc_HOST_ARCH)
......@@ -1868,7 +1916,7 @@ error:
void
insertSymbol(pathchar* obj_name, char* key, void* data)
{
ghciInsertStrHashTable(obj_name, symhash, key, data);
ghciInsertSymbolTable(obj_name, symhash, key, data, HS_BOOL_FALSE, NULL);
}
/* -----------------------------------------------------------------------------
......@@ -1881,9 +1929,8 @@ lookupSymbol( char *lbl )
IF_DEBUG(linker, debugBelch("lookupSymbol: looking up %s\n", lbl));
initLinker() ;
ASSERT(symhash != NULL);
val = lookupStrHashTable(symhash, lbl);
if (val == NULL) {
if (!ghciLookupSymbolTable(symhash, lbl, &val)) {
IF_DEBUG(linker, debugBelch("lookupSymbol: symbol not found\n"));
# if defined(OBJFORMAT_ELF)
return internal_dlsym(dl_prog_handle, lbl);
......@@ -1986,7 +2033,7 @@ void ghci_enquire ( char* addr )
if (sym == NULL) continue;
a = NULL;
if (a == NULL) {
a = lookupStrHashTable(symhash, sym);
ghciLookupSymbolTable(symhash, sym, (void **)&a);
}
if (a == NULL) {
// debugBelch("ghci_enquire: can't find %s\n", sym);
......@@ -2854,7 +2901,7 @@ unloadObj( pathchar *path )
int i;
for (i = 0; i < oc->n_symbols; i++) {
if (oc->symbols[i] != NULL) {
removeStrHashTable(symhash, oc->symbols[i], NULL);
ghciRemoveSymbolTable(symhash, oc->symbols[i], oc);
}
}
}
......@@ -3978,7 +4025,8 @@ ocGetNames_PEi386 ( ObjectCode* oc )
ASSERT(i >= 0 && i < oc->n_symbols);
/* cstring_from_COFF_symbol_name always succeeds. */
oc->symbols[i] = (char*)sname;
ghciInsertStrHashTable(oc->fileName, symhash, (char*)sname, addr);
ghciInsertSymbolTable(oc->fileName, symhash, (char*)sname, addr,
HS_BOOL_FALSE, oc);
} else {
# if 0
debugBelch(
......@@ -4820,6 +4868,7 @@ ocGetNames_ELF ( ObjectCode* oc )
for (j = 0; j < nent; j++) {
char isLocal = FALSE; /* avoids uninit-var warning */
HsBool isWeak = HS_BOOL_FALSE;
char* ad = NULL;
char* nm = strtab + stab[j].st_name;
int secno = stab[j].st_shndx;
......@@ -4840,6 +4889,7 @@ ocGetNames_ELF ( ObjectCode* oc )
else
if ( ( ELF_ST_BIND(stab[j].st_info)==STB_GLOBAL
|| ELF_ST_BIND(stab[j].st_info)==STB_LOCAL
|| ELF_ST_BIND(stab[j].st_info)==STB_WEAK
)
/* and not an undefined symbol */
&& stab[j].st_shndx != SHN_UNDEF
......@@ -4863,7 +4913,8 @@ ocGetNames_ELF ( ObjectCode* oc )
ad = ehdrC + shdr[ secno ].sh_offset + stab[j].st_value;
if (ELF_ST_BIND(stab[j].st_info)==STB_LOCAL) {
isLocal = TRUE;
} else {
isWeak = FALSE;
} else { /* STB_GLOBAL or STB_WEAK */
#ifdef ELF_FUNCTION_DESC
/* dlsym() and the initialisation table both give us function
* descriptors, so to be consistent we store function descriptors
......@@ -4874,6 +4925,7 @@ ocGetNames_ELF ( ObjectCode* oc )
IF_DEBUG(linker,debugBelch( "addOTabName(GLOB): %10p %s %s\n",
ad, oc->fileName, nm ));
isLocal = FALSE;
isWeak = (ELF_ST_BIND(stab[j].st_info)==STB_WEAK);
}
}
......@@ -4886,7 +4938,7 @@ ocGetNames_ELF ( ObjectCode* oc )
if (isLocal) {
/* Ignore entirely. */
} else {
ghciInsertStrHashTable(oc->fileName, symhash, nm, ad);
ghciInsertSymbolTable(oc->fileName, symhash, nm, ad, isWeak, oc);
}
} else {
/* Skip. */
......@@ -6579,11 +6631,13 @@ ocGetNames_MachO(ObjectCode* oc)
else
{
IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting %s\n", nm));
ghciInsertStrHashTable(oc->fileName, symhash, nm,
ghciInsertSymbolTable(oc->fileName, symhash, nm,
image
+ sections[nlist[i].n_sect-1].offset
- sections[nlist[i].n_sect-1].addr
+ nlist[i].n_value);
+ nlist[i].n_value,
HS_BOOL_FALSE,
oc);
oc->symbols[curSymbol++] = nm;
}
}
......@@ -6614,8 +6668,8 @@ ocGetNames_MachO(ObjectCode* oc)
nlist[i].n_value = commonCounter;
IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting common symbol: %s\n", nm));
ghciInsertStrHashTable(oc->fileName, symhash, nm,
(void*)commonCounter);
ghciInsertSymbolTable(oc->fileName, symhash, nm,
(void*)commonCounter, HS_BOOL_FALSE, oc);
oc->symbols[curSymbol++] = nm;
commonCounter += sz;
......@@ -6785,7 +6839,7 @@ machoInitSymbolsWithoutUnderscore(void)
#undef SymI_NeedsProto
#define SymI_NeedsProto(x) \
ghciInsertStrHashTable("(GHCi built-in symbols)", symhash, #x, *p++);
ghciInsertSymbolTable("(GHCi built-in symbols)", symhash, #x, *p++, HS_BOOL_FALSE, NULL);
RTS_MACHO_NOUNDERLINE_SYMBOLS
......
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