Author: trociny
Date: Thu Sep 27 14:55:15 2012
New Revision: 240997
URL: http://svn.freebsd.org/changeset/base/240997
Log:
Kernel and modules have "set_vnet" linker set, where virtualized
global variables are placed. When a module is loaded by link_elf
linker its variables from "set_vnet" linker set are copied to the
kernel "set_vnet" ("modspace") and all references to these variables
inside the module are relocated accordingly.
The issue is when a module is loaded that has references to global
variables from another, previously loaded module: these references are
not relocated so an invalid address is used when the module tries to
access the variable. The example is V_layer3_chain, defined in ipfw
module and accessed from ipfw_nat.
The same issue is with DPCPU variables, which use "set_pcpu" linker
set.
Fix this making the link_elf linker on a module load recognize
"external" DPCPU/VNET variables defined in the previously loaded
modules and relocate them accordingly. For this set_pcpu_list and
set_vnet_list are used, where the addresses of modules' "set_pcpu" and
"set_vnet" linker sets are stored.
Note, archs that use link_elf_obj (amd64) were not affected by this
issue.
Reviewed by: jhb, julian, zec (initial version)
MFC after: 1 month
Modified:
head/sys/kern/link_elf.c
Modified: head/sys/kern/link_elf.c
==============================================================================
--- head/sys/kern/link_elf.c Thu Sep 27 14:29:18 2012 (r240996)
+++ head/sys/kern/link_elf.c Thu Sep 27 14:55:15 2012 (r240997)
@@ -123,6 +123,15 @@ typedef struct elf_file {
#endif
} *elf_file_t;
+struct elf_set {
+ Elf_Addr es_start;
+ Elf_Addr es_stop;
+ Elf_Addr es_base;
+ TAILQ_ENTRY(elf_set) es_link;
+};
+
+TAILQ_HEAD(elf_set_head, elf_set);
+
#include <kern/kern_ctf.c>
static int link_elf_link_common_finish(linker_file_t);
@@ -181,6 +190,75 @@ static int parse_dynamic(elf_file_t);
static int relocate_file(elf_file_t);
static int link_elf_preload_parse_symbols(elf_file_t);
+static struct elf_set_head set_pcpu_list;
+#ifdef VIMAGE
+static struct elf_set_head set_vnet_list;
+#endif
+
+static void
+elf_set_add(struct elf_set_head *list, Elf_Addr start, Elf_Addr stop, Elf_Addr
base)
+{
+ struct elf_set *set, *iter;
+
+ set = malloc(sizeof(*set), M_LINKER, M_WAITOK);
+ set->es_start = start;
+ set->es_stop = stop;
+ set->es_base = base;
+
+ TAILQ_FOREACH(iter, list, es_link) {
+
+ KASSERT((set->es_start < iter->es_start && set->es_stop <
iter->es_stop) ||
+ (set->es_start > iter->es_start && set->es_stop >
iter->es_stop),
+ ("linker sets intersection: to insert: 0x%jx-0x%jx;
inserted: 0x%jx-0x%jx",
+ (uintmax_t)set->es_start, (uintmax_t)set->es_stop,
+ (uintmax_t)iter->es_start, (uintmax_t)iter->es_stop));
+
+ if (iter->es_start > set->es_start) {
+ TAILQ_INSERT_BEFORE(iter, set, es_link);
+ break;
+ }
+ }
+
+ if (iter == NULL)
+ TAILQ_INSERT_TAIL(list, set, es_link);
+}
+
+static int
+elf_set_find(struct elf_set_head *list, Elf_Addr addr, Elf_Addr *start,
Elf_Addr *base)
+{
+ struct elf_set *set;
+
+ TAILQ_FOREACH(set, list, es_link) {
+ if (addr < set->es_start)
+ return (0);
+ if (addr < set->es_stop) {
+ *start = set->es_start;
+ *base = set->es_base;
+ return (1);
+ }
+ }
+
+ return (0);
+}
+
+static void
+elf_set_delete(struct elf_set_head *list, Elf_Addr start)
+{
+ struct elf_set *set;
+
+ TAILQ_FOREACH(set, list, es_link) {
+ if (start < set->es_start)
+ break;
+ if (start == set->es_start) {
+ TAILQ_REMOVE(list, set, es_link);
+ free(set, M_LINKER);
+ return;
+ }
+ }
+ KASSERT(0, ("deleting unknown linker set (start = 0x%jx)",
+ (uintmax_t)start));
+}
+
#ifdef GDB
static void r_debug_state(struct r_debug *, struct link_map *);
@@ -345,6 +423,10 @@ link_elf_init(void* arg)
(void)link_elf_link_common_finish(linker_kernel_file);
linker_kernel_file->flags |= LINKER_FILE_LINKED;
+ TAILQ_INIT(&set_pcpu_list);
+#ifdef VIMAGE
+ TAILQ_INIT(&set_vnet_list);
+#endif
}
SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0);
@@ -515,6 +597,8 @@ parse_dpcpu(elf_file_t ef)
return (ENOSPC);
memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, count);
dpcpu_copy((void *)ef->pcpu_base, count);
+ elf_set_add(&set_pcpu_list, ef->pcpu_start, ef->pcpu_stop,
+ ef->pcpu_base);
return (0);
}
@@ -544,6 +628,8 @@ parse_vnet(elf_file_t ef)
return (ENOSPC);
memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, count);
vnet_data_copy((void *)ef->vnet_base, count);
+ elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
+ ef->vnet_base);
return (0);
}
@@ -996,11 +1082,13 @@ link_elf_unload_file(linker_file_t file)
if (ef->pcpu_base != 0) {
dpcpu_free((void *)ef->pcpu_base,
ef->pcpu_stop - ef->pcpu_start);
+ elf_set_delete(&set_pcpu_list, ef->pcpu_start);
}
#ifdef VIMAGE
if (ef->vnet_base != 0) {
vnet_data_free((void *)ef->vnet_base,
ef->vnet_stop - ef->vnet_start);
+ elf_set_delete(&set_vnet_list, ef->vnet_start);
}
#endif
#ifdef GDB
@@ -1439,6 +1527,7 @@ elf_lookup(linker_file_t lf, Elf_Size sy
elf_file_t ef = (elf_file_t)lf;
const Elf_Sym *sym;
const char *symbol;
+ Elf_Addr addr, start, base;
/* Don't even try to lookup the symbol if the index is bogus. */
if (symidx >= ef->nchains)
@@ -1470,7 +1559,15 @@ elf_lookup(linker_file_t lf, Elf_Size sy
if (*symbol == 0)
return (0);
- return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
+ addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
+
+ if (elf_set_find(&set_pcpu_list, addr, &start, &base))
+ addr = addr - start + base;
+#ifdef VIMAGE
+ else if (elf_set_find(&set_vnet_list, addr, &start, &base))
+ addr = addr - start + base;
+#endif
+ return addr;
}
static void
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