[Bug runtime/10001] New: 32-bit map error "array subscript is above array bounds"

["jistone at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

On kernel 2.6.29-0.258.rc8.git2.fc11.i686.PAE, I get an error from
systemtap.base/overload.exp.  I distilled the triggering script down to the
following:

# stap -e 'global k; probe begin { k["foo"] = 0 }' --vp 0002
Running make -C "/lib/modules/2.6.29-0.258.rc8.git2.fc11.i686.PAE/build"
M="/tmp/stapQJkCVd" modules >/dev/null
cc1: warnings being treated as errors
/tmp/stapQJkCVd/stap_f59c71419a2c37ad1f014c89e1bd68e4_372.c: In function
?probe_1383?:
/usr/src/kernels/2.6.29-0.258.rc8.git2.fc11.i686.PAE/arch/x86/include/asm/string_32.h:75:
error: array subscript is above array bounds
make[1]: *** [/tmp/stapQJkCVd/stap_f59c71419a2c37ad1f014c89e1bd68e4_372.o] Error 1
make: *** [_module_/tmp/stapQJkCVd] Error 2
Pass 4: compiled C into "stap_f59c71419a2c37ad1f014c89e1bd68e4_372.ko" in
1310usr/1370sys/7652real ms.
Pass 4: compilation failed.  Try again with another '--vp 0001' option.
Running rm -rf /tmp/stapQJkCVd

The generated code is:
160     (void)
161     ({
162       c->last_stmt = "identifier 'k' at <input>:1:25";
163       l->__tmp2 = ((int64_t)0LL);
164       { int rc = _stp_map_set_si (global.s_k, "foo", l->__tmp2); if
(unlikely(rc)) { c->last_error = "Array overflow, check MAXMAPENTRIES"; goto
out; }};
165       ((int64_t)0LL);
166     });

And the relevant excerpt from asm/string_32.h:
51 static __always_inline void *__constant_memcpy(void *to, const void *from,
52                            size_t n)
53 {
54     long esi, edi;
55     if (!n)
56         return to;
57 
58     switch (n) {
[...]
73     case 5:
74         *(int *)to = *(int *)from;
75         *((char *)to + 4) = *((char *)from + 4);
76         return to;

The important factor seems to be the length of the key = 3.  Keys of length 2
also show the same error on line 75.  Lengths 1 or 4+ seem to have no issue.

The same kernel on x86_64 works fine.

-- 
           Summary: 32-bit map error "array subscript is above array bounds"
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: runtime
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: jistone at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=10001

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