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https://github.com/crash-utility/crash
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Fix for the x86_64 "bt" command for kernels that are configured with
CONFIG_FRAME_POINTER. Without the patch, the per-text-return-address framesize cache may contain invalid entries for functions that have an "and $0xfffffffffffffff0,%rsp" instruction in their prologue, which aligns the stack on a 16-byte boundary; therefore any cached framesize for a text-return-address in such a function may be incorrect depending upon the alignment of the stack address of a calling function. If an invalid cached framesize is utilized by "bt", the backtrace may skip over several frames, or may display one or more invalid (stale) frames. The patch introduces a new cache that contains functions for which framesize values should not be cached. (anderson@redhat.com)
This commit is contained in:
Dave Anderson
parent
6088a29f7e
commit
33421b0b5a
144
x86_64.c
144
x86_64.c
@ -118,7 +118,8 @@ static void x86_64_init_hyper(int);
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static ulong x86_64_get_stackbase_hyper(ulong);
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static ulong x86_64_get_stacktop_hyper(ulong);
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static int x86_64_framesize_cache_resize(void);
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static int x86_64_framesize_cache_func(int, ulong, int *, int);
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static int x86_64_do_not_cache_framesize(struct syment *, ulong);
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static int x86_64_framesize_cache_func(int, ulong, int *, int, struct syment *);
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static ulong x86_64_get_framepointer(struct bt_info *, ulong);
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int search_for_eframe_target_caller(struct bt_info *, ulong, int *);
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static int x86_64_get_framesize(struct bt_info *, ulong, ulong);
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@ -7843,8 +7844,90 @@ x86_64_framesize_cache_resize(void)
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return TRUE;
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}
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ulong *x86_64_framesize_no_cache = NULL;
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static int framesize_no_cache_entries = 0;
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#define FRAMESIZE_NO_CACHE_INCR (10)
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static int
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x86_64_framesize_cache_func(int cmd, ulong textaddr, int *framesize, int exception)
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x86_64_do_not_cache_framesize(struct syment *sp, ulong textaddr)
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{
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int c, instr, arg;
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char buf[BUFSIZE];
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char *arglist[MAXARGS];
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ulong *new_fnc;
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if (x86_64_framesize_no_cache[framesize_no_cache_entries-1]) {
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if ((new_fnc = realloc(x86_64_framesize_no_cache,
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(framesize_no_cache_entries+FRAMESIZE_NO_CACHE_INCR) *
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sizeof(ulong))) == NULL) {
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error(INFO, "cannot realloc x86_64_framesize_no_cache space!\n");
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return FALSE;
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}
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x86_64_framesize_no_cache = new_fnc;
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for (c = framesize_no_cache_entries;
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c < framesize_no_cache_entries + FRAMESIZE_NO_CACHE_INCR; c++)
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x86_64_framesize_no_cache[c] = 0;
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framesize_no_cache_entries += FRAMESIZE_NO_CACHE_INCR;
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}
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for (c = 0; c < framesize_no_cache_entries; c++)
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if (x86_64_framesize_no_cache[c] == sp->value)
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return TRUE;
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if (!accessible(sp->value))
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return FALSE;
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sprintf(buf, "disassemble 0x%lx,0x%lx", sp->value, textaddr);
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open_tmpfile2();
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if (!gdb_pass_through(buf, pc->tmpfile2, GNU_RETURN_ON_ERROR)) {
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close_tmpfile2();
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return FALSE;
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}
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rewind(pc->tmpfile2);
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instr = arg = -1;
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while (fgets(buf, BUFSIZE, pc->tmpfile2)) {
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if (STRNEQ(buf, "Dump of assembler code"))
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continue;
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else if (STRNEQ(buf, "End of assembler dump."))
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break;
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else if ((c = parse_line(buf, arglist)) < 3)
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continue;
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if (instr == -1) {
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if (LASTCHAR(arglist[0]) == ':') {
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instr = 1;
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arg = 2;
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} else {
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instr = 2;
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arg = 3;
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}
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}
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if (STREQ(arglist[instr], "and") &&
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STREQ(arglist[arg], "$0xfffffffffffffff0,%rsp")) {
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close_tmpfile2();
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for (c = 0; c < framesize_no_cache_entries; c++) {
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if (x86_64_framesize_no_cache[c] == 0) {
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x86_64_framesize_no_cache[c] = sp->value;
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break;
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}
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}
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return TRUE;
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}
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if (STREQ(arglist[instr], "callq"))
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break;
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}
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close_tmpfile2();
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return FALSE;
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}
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static int
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x86_64_framesize_cache_func(int cmd, ulong textaddr, int *framesize, int exception, struct syment *sp)
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{
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int i, n;
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struct framesize_cache *fc;
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@ -7856,6 +7939,10 @@ x86_64_framesize_cache_func(int cmd, ulong textaddr, int *framesize, int excepti
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sizeof(struct framesize_cache))) == NULL)
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error(FATAL,
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"cannot calloc x86_64_framesize_cache space!\n");
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framesize_no_cache_entries = FRAMESIZE_NO_CACHE_INCR;
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if ((x86_64_framesize_no_cache = calloc(framesize_no_cache_entries,
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sizeof(ulong))) == NULL)
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error(FATAL, "cannot calloc x86_64_framesize_no_cache space!\n");
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}
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switch (cmd)
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@ -7873,6 +7960,8 @@ x86_64_framesize_cache_func(int cmd, ulong textaddr, int *framesize, int excepti
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return FALSE;
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case FRAMESIZE_ENTER:
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if (sp && x86_64_do_not_cache_framesize(sp, textaddr))
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return *framesize;
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retry:
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fc = &x86_64_framesize_cache[0];
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for (i = 0; i < framesize_cache_entries; i++, fc++) {
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@ -7901,21 +7990,36 @@ retry:
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return *framesize;
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case FRAMESIZE_DUMP:
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fprintf(fp, "framesize_cache_entries:\n");
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fc = &x86_64_framesize_cache[0];
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for (i = 0; i < framesize_cache_entries; i++, fc++) {
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if (fc->textaddr == 0) {
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if (i < (framesize_cache_entries-1)) {
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fprintf(fp, "[%d-%d]: (unused)\n",
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fprintf(fp, " [%d-%d]: (unused)\n",
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i, framesize_cache_entries-1);
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}
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break;
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}
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fprintf(fp, "[%3d]: %lx %3d %s (%s)\n", i,
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fprintf(fp, " [%3d]: %lx %3d %s (%s)\n", i,
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fc->textaddr, fc->framesize,
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fc->exception ? "EX" : "CF",
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value_to_symstr(fc->textaddr, buf, 0));
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}
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fprintf(fp, "\nframesize_no_cache_entries:\n");
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for (i = 0; i < framesize_no_cache_entries; i++) {
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if (x86_64_framesize_no_cache[i])
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fprintf(fp, " [%3d]: %lx (%s)\n",
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i, x86_64_framesize_no_cache[i],
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value_to_symstr(x86_64_framesize_no_cache[i], buf, 0));
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else {
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fprintf(fp, " [%d-%d]: (unused)\n",
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i, framesize_no_cache_entries-1);
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break;
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}
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}
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break;
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}
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@ -8044,7 +8148,7 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp)
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if (!(bt->flags & BT_FRAMESIZE_DEBUG) &&
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x86_64_framesize_cache_func(FRAMESIZE_QUERY, textaddr, &framesize,
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exception)) {
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exception, NULL)) {
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if (framesize == -1)
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bt->flags |= BT_FRAMESIZE_DISABLE;
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return framesize;
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@ -8081,7 +8185,7 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp)
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else
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framesize = 8;
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return (x86_64_framesize_cache_func(FRAMESIZE_ENTER, textaddr,
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&framesize, exception));
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&framesize, exception, NULL));
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}
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if ((machdep->flags & FRAMEPOINTER) &&
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@ -8099,7 +8203,7 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp)
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if (framepointer) {
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framesize = framepointer - rsp;
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return (x86_64_framesize_cache_func(FRAMESIZE_ENTER,
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textaddr, &framesize, 0));
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textaddr, &framesize, 0, sp));
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}
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}
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@ -8117,7 +8221,7 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp)
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if ((korc->type == ORC_TYPE_CALL) && (korc->sp_reg == ORC_REG_SP)) {
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framesize = (korc->sp_offset - 8);
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return (x86_64_framesize_cache_func(FRAMESIZE_ENTER, textaddr,
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&framesize, exception));
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&framesize, exception, NULL));
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}
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}
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@ -8238,7 +8342,7 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp)
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textaddr = textaddr_save;
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return (x86_64_framesize_cache_func(FRAMESIZE_ENTER, textaddr,
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&framesize, exception));
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&framesize, exception, NULL));
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}
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static void
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@ -8252,18 +8356,20 @@ x86_64_framesize_debug(struct bt_info *bt)
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switch (bt->hp->esp)
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{
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case 1: /* "dump" */
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x86_64_framesize_cache_func(FRAMESIZE_DUMP, 0, NULL, 0);
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x86_64_framesize_cache_func(FRAMESIZE_DUMP, 0, NULL, 0, NULL);
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break;
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case 0:
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if (bt->hp->eip) { /* clear one entry */
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framesize = -1;
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x86_64_framesize_cache_func(FRAMESIZE_ENTER, bt->hp->eip,
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&framesize, exception);
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&framesize, exception, NULL);
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} else { /* clear all entries */
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BZERO(&x86_64_framesize_cache[0],
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sizeof(struct framesize_cache)*framesize_cache_entries);
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fprintf(fp, "framesize cache cleared\n");
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BZERO(&x86_64_framesize_no_cache[0],
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sizeof(ulong)*framesize_no_cache_entries);
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fprintf(fp, "framesize caches cleared\n");
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}
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break;
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@ -8278,16 +8384,20 @@ x86_64_framesize_debug(struct bt_info *bt)
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machdep->flags |= FRAMEPOINTER;
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BZERO(&x86_64_framesize_cache[0],
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sizeof(struct framesize_cache)*framesize_cache_entries);
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BZERO(&x86_64_framesize_no_cache[0],
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sizeof(ulong)*framesize_no_cache_entries);
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fprintf(fp,
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"framesize cache cleared and FRAMEPOINTER turned ON\n");
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"framesize caches cleared and FRAMEPOINTER turned ON\n");
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break;
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case -4:
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machdep->flags &= ~FRAMEPOINTER;
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BZERO(&x86_64_framesize_cache[0],
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sizeof(struct framesize_cache)*framesize_cache_entries);
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BZERO(&x86_64_framesize_no_cache[0],
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sizeof(ulong)*framesize_no_cache_entries);
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fprintf(fp,
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"framesize cache cleared and FRAMEPOINTER turned OFF\n");
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"framesize caches cleared and FRAMEPOINTER turned OFF\n");
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break;
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case -5:
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@ -8302,7 +8412,7 @@ x86_64_framesize_debug(struct bt_info *bt)
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framesize = bt->hp->esp;
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if (bt->hp->eip)
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x86_64_framesize_cache_func(FRAMESIZE_ENTER, bt->hp->eip,
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&framesize, exception);
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&framesize, exception, NULL);
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} else
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error(INFO, "x86_64_framesize_debug: ignoring command\n");
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break;
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@ -8329,7 +8439,7 @@ __schedule_frame_adjust(ulong rsp_in, struct bt_info *bt)
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rsp_in, bt->stackbase, bt->stacktop, bt->tc->processor);
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if (x86_64_framesize_cache_func(FRAMESIZE_QUERY,
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machdep->machspec->thread_return, &framesize, 0)) {
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machdep->machspec->thread_return, &framesize, 0, NULL)) {
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rsp = rsp_in + framesize;
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i = (rsp - bt->stackbase)/sizeof(ulong);
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up = (ulong *)(&bt->stackbuf[i*sizeof(ulong)]);
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@ -8357,7 +8467,7 @@ __schedule_frame_adjust(ulong rsp_in, struct bt_info *bt)
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bt->instptr = *up;
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x86_64_framesize_cache_func(FRAMESIZE_ENTER,
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machdep->machspec->thread_return,
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&framesize, 0);
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&framesize, 0, NULL);
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bt->instptr = *up;
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found = TRUE;
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break;
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