On 04/25/2016 04:35 PM, Konrad Rzeszutek Wilk wrote:
snip
+static DEFINE_RCU_READ_LOCK(rcu_applied_lock);
static LIST_HEAD(applied_list);
static unsigned int payload_cnt;
@@ -56,6 +57,8 @@ struct payload {
unsigned int nfuncs; /* Nr of functions to patch. */
const struct xsplice_symbol *symtab; /* All symbols. */
const char *strtab; /* Pointer to .strtab. */
+ struct virtual_region region; /* symbol, bug.frame patching and
+ exception table (x86). */
unsigned int nsyms; /* Nr of entries in .strtab and
symbols. */
char name[XEN_XSPLICE_NAME_SIZE]; /* Name of it. */
};
@@ -142,6 +145,55 @@ void *xsplice_symbols_lookup_by_name(const char *symname)
return 0;
}
+static const char *xsplice_symbols_lookup(unsigned long addr,
+ unsigned long *symbolsize,
+ unsigned long *offset,
+ char *namebuf)
+{
+ const struct payload *data;
+ unsigned int i, best;
+ const void *va = (const void *)addr;
+ const char *n = NULL;
+
+ /*
+ * Only RCU locking since this list is only ever changed during apply
+ * or revert context. And in case it dies there we need an safe list.
+ */
+ rcu_read_lock(&rcu_applied_lock);
+ list_for_each_entry_rcu ( data, &applied_list, applied_list )
+ {
+ if ( va < data->text_addr &&
+ va >= (data->text_addr + data->pages * PAGE_SIZE) )
This calculation is wrong due to the use of void * and results in
incorrect backtrace results.
You also need to have || rather than &&.
Additionally, I think it should use data->text_size rather than
data->pages * PAGE_SIZE.
+ continue;
+
+ best = UINT_MAX;
+
+ for ( i = 0; i < data->nsyms; i++ )
+ {
+ if ( data->symtab[i].value <= va &&
+ (best == UINT_MAX ||
+ data->symtab[best].value < data->symtab[i].value) )
+ best = i;
+ }
+
+ if ( best == UINT_MAX )
+ break;
+
+ if ( symbolsize )
+ *symbolsize = data->symtab[best].size;
+ if ( offset )
+ *offset = va - data->symtab[best].value;
+ if ( namebuf )
+ strlcpy(namebuf, data->name, KSYM_NAME_LEN);
+
+ n = data->symtab[best].name;
+ break;
+ }
+ rcu_read_unlock(&rcu_applied_lock);
+
+ return n;
+}
+
static struct payload *find_payload(const char *name)
{
struct payload *data, *found = NULL;
@@ -366,6 +418,7 @@ static int prepare_payload(struct payload *payload,
const struct xsplice_elf_sec *sec;
unsigned int i;
struct xsplice_patch_func *f;
+ struct virtual_region *region;
sec = xsplice_elf_sec_by_name(elf, ELF_XSPLICE_FUNC);
ASSERT(sec);
@@ -422,6 +475,13 @@ static int prepare_payload(struct payload *payload,
}
}
+ /* Setup the virtual region with proper data. */
+ region = &payload->region;
+
+ region->symbols_lookup = xsplice_symbols_lookup;
+ region->start = payload->text_addr;
+ region->end = payload->text_addr + payload->text_size;
This calculation is wrong due to the use of void *.
--
Ross Lagerwall
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