--- a/hotspot/src/os/aix/vm/porting_aix.cpp Mon Nov 02 09:13:39 2015 +0100
+++ b/hotspot/src/os/aix/vm/porting_aix.cpp Fri Oct 30 12:36:54 2015 +0100
@@ -23,11 +23,13 @@
*/
#include "asm/assembler.hpp"
+#include "loadlib_aix.hpp"
#include "memory/allocation.hpp"
#include "memory/allocation.inline.hpp"
+// For CritSect
+#include "misc_aix.hpp"
+#include "porting_aix.hpp"
#include "runtime/os.hpp"
-#include "loadlib_aix.hpp"
-#include "porting_aix.hpp"
#include "utilities/debug.hpp"
#include <demangle.h>
@@ -45,23 +47,6 @@
#define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))
-// Align a pointer without having to cast.
-inline char* align_ptr_up(char* ptr, intptr_t alignment) {
- return (char*) align_size_up((intptr_t)ptr, alignment);
-}
-
-// Trace if verbose to tty.
-// I use these now instead of the Xtrace system because the latter is
-// not available at init time, hence worthless. Until we fix this, all
-// tracing here is done with -XX:+Verbose.
-#define trcVerbose(fmt, ...) { \
- if (Verbose) { \
- fprintf(stderr, fmt, ##__VA_ARGS__); \
- fputc('\n', stderr); fflush(stderr); \
- } \
-}
-#define ERRBYE(s) { trcVerbose(s); return -1; }
-
// Unfortunately, the interface of dladdr makes the implementator
// responsible for maintaining memory for function name/library
// name. I guess this is because most OS's keep those values as part
@@ -139,18 +124,37 @@
ERRBYE("invalid program counter");
}
+ // We see random but frequent crashes in this function since some months mainly on shutdown
+ // (-XX:+DumpInfoAtExit). It appears the page we are reading is randomly disappearing while
+ // we read it (?).
+ // As the pc cannot be trusted to be anything sensible lets make all reads via SafeFetch. Also
+ // bail if this is not a text address right now.
+ if (!LoadedLibraries::find_for_text_address(pc, NULL)) {
+ ERRBYE("not a text address");
+ }
+
+ // .. (Note that is_readable_pointer returns true if safefetch stubs are not there yet;
+ // in that case I try reading the traceback table unsafe - I rather risk secondary crashes in
+ // error files than not having a callstack.)
+#define CHECK_POINTER_READABLE(p) \
+ if (!MiscUtils::is_readable_pointer(p)) { \
+ ERRBYE("pc not readable"); \
+ }
+
codeptr_t pc2 = pc;
- // make sure the pointer is word aligned.
+ // Make sure the pointer is word aligned.
pc2 = (codeptr_t) align_ptr_up((char*)pc2, 4);
+ CHECK_POINTER_READABLE(pc2)
// Find start of traceback table.
// (starts after code, is marked by word-aligned (32bit) zeros)
while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {
+ CHECK_POINTER_READABLE(pc2)
pc2++;
}
if (*pc2 != 0) {
- ERRBYE("could not find traceback table within 5000 bytes of program counter");
+ ERRBYE("no traceback table found");
}
//
// Set up addressability to the traceback table
@@ -162,7 +166,7 @@
if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {
// Language specifiers, go from 0 (C) to 14 (Objective C).
// According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.
- ERRBYE("not a traceback table");
+ ERRBYE("no traceback table found");
}
// Existence of fields in the tbtable extension are contingent upon
@@ -173,6 +177,8 @@
if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)
pc2++;
+ CHECK_POINTER_READABLE(pc2)
+
if (tb->tb.has_tboff == TRUE) {
// I want to know the displacement
@@ -182,7 +188,7 @@
// Weed out the cases where we did find the wrong traceback table.
if (pc < start_of_procedure) {
- ERRBYE("could not find (the real) traceback table within 5000 bytes of program counter");
+ ERRBYE("no traceback table found");
}
// return the displacement
@@ -204,15 +210,24 @@
if (tb->tb.has_ctl == TRUE)
pc2 += (*pc2) + 1; // don't care
+ CHECK_POINTER_READABLE(pc2)
+
//
// return function name if it exists.
//
if (p_name && namelen > 0) {
if (tb->tb.name_present) {
+ // Copy name from text because it may not be zero terminated.
+ // 256 is good enough for most cases; do not use large buffers here.
char buf[256];
const short l = MIN2<short>(*((short*)pc2), sizeof(buf) - 1);
- memcpy(buf, (char*)pc2 + sizeof(short), l);
- buf[l] = '\0';
+ // Be very careful.
+ int i = 0; char* const p = (char*)pc2 + sizeof(short);
+ while (i < l && MiscUtils::is_readable_pointer(p + i)) {
+ buf[i] = p[i];
+ i++;
+ }
+ buf[i] = '\0';
p_name[0] = '\0';
@@ -275,7 +290,8 @@
info->dli_saddr = NULL;
address p = (address) addr;
- const LoadedLibraryModule* lib = NULL;
+ loaded_module_t lm;
+ bool found = false;
enum { noclue, code, data } type = noclue;
@@ -284,28 +300,28 @@
// Note: input address may be a function. I accept both a pointer to
// the entry of a function and a pointer to the function decriptor.
// (see ppc64 ABI)
- lib = LoadedLibraries::find_for_text_address(p);
- if (lib) {
+ found = LoadedLibraries::find_for_text_address(p, &lm);
+ if (found) {
type = code;
}
- if (!lib) {
+ if (!found) {
// Not a pointer into any text segment. Is it a function descriptor?
const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;
p = pfd->entry();
if (p) {
- lib = LoadedLibraries::find_for_text_address(p);
- if (lib) {
+ found = LoadedLibraries::find_for_text_address(p, &lm);
+ if (found) {
type = code;
}
}
}
- if (!lib) {
+ if (!found) {
// Neither direct code pointer nor function descriptor. A data ptr?
p = (address)addr;
- lib = LoadedLibraries::find_for_data_address(p);
- if (lib) {
+ found = LoadedLibraries::find_for_data_address(p, &lm);
+ if (found) {
type = data;
}
}
@@ -313,12 +329,10 @@
// If we did find the shared library this address belongs to (either
// code or data segment) resolve library path and, if possible, the
// symbol name.
- if (lib) {
- const char* const interned_libpath =
- dladdr_fixed_strings.intern(lib->get_fullpath());
- if (interned_libpath) {
- info->dli_fname = interned_libpath;
- }
+ if (found) {
+
+ // No need to intern the libpath, that one is already interned one layer below.
+ info->dli_fname = lm.path;
if (type == code) {
@@ -328,7 +342,7 @@
int displacement = 0;
if (getFuncName((codeptr_t) p, funcname, sizeof(funcname), &displacement,
- NULL, NULL, 0, true /* demangle */) == 0) {
+ NULL, NULL, 0, false) == 0) {
if (funcname[0] != '\0') {
const char* const interned = dladdr_fixed_strings.intern(funcname);
info->dli_sname = interned;