On 02/15/2018 02:21 PM, Pavel Labath wrote:
I've tried your sample, and I was indeed able to reproduce the
problem. What makes your case special is that "sin" and "cos" are
indirect functions (STT_GNU_IFUNC), so we have to do some extra work
(call the resolver function) to resolve them.
I've changed my sample to dlsym() a regular function instead of an indirect
stub, and got a breakpoint hit, but:
(lldb) attach 16196
Process 16196 stopped
* thread #1, name = 'main', stop reason = signal SIGSTOP
frame #0: 0x0000000000400798 main`main(argc=1, argv=0x00007ffd6f662668) at
main.c:16
13 for (a = 0; a < DELAY + argc; a++)
14 for (b = 0; b < DELAY + argc; b++)
15 for (c = 0; c < DELAY + argc; c++)
-> 16 z += a + b + c;
17 while (1)
18 {
19 void *handle = dlopen ("libfoo.so", RTLD_LAZY);
Executable module set to "/home/dantipov/tmp/t-dl2/main".
Architecture set to: x86_64--linux.
(lldb) breakpoint set -n foo
Breakpoint 1: no locations (pending).
WARNING: Unable to resolve breakpoint to any actual locations.
(lldb) process continue
Process 16196 resuming
1 location added to breakpoint 1
(lldb) error: ld-linux-x86-64.so.2 0x0005d207: adding range [0x14eea-0x14f5a) which has a base that is less than the function's low PC 0x15730. Please file a bug and attach the file at the start of
this error message
error: ld-linux-x86-64.so.2 0x0005d207: adding range [0x14f70-0x14f76) which has a base that is less than the function's low PC 0x15730. Please file a bug and attach the file at the start of this
error message
error: ld-linux-x86-64.so.2 0x0005d268: adding range [0x14eea-0x14f5a) which has a base that is less than the function's low PC 0x15730. Please file a bug and attach the file at the start of this
error message
error: ld-linux-x86-64.so.2 0x0005d268: adding range [0x14f70-0x14f76) which has a base that is less than the function's low PC 0x15730. Please file a bug and attach the file at the start of this
error message
Process 16196 stopped
* thread #1, name = 'main', stop reason = breakpoint 1.1
frame #0: 0x00007f3b1a8536f7
libfoo.so`foo(v=0.00000000000003907985046680551) at libfoo.c:6
3 double
4 foo (double v)
5 {
-> 6 return sin (v) + cos (v);
7 }
This seems to be an another bug, isn't it?
Dmitry
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#include <math.h>
double
foo (double v)
{
return sin (v) + cos (v);
}
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <dlfcn.h>
#define DELAY 2000
int
main (int argc, char *argv[])
{
/* Busy loop long enough to attach the debugger before dlopen happens. */
int a, b, c, z = 0;
for (a = 0; a < DELAY + argc; a++)
for (b = 0; b < DELAY + argc; b++)
for (c = 0; c < DELAY + argc; c++)
z += a + b + c;
while (1)
{
void *handle = dlopen ("libfoo.so", RTLD_LAZY);
if (handle)
{
int i;
double sum = 0.0;
double (*fooptr) (double) = dlsym (handle, "foo");
for (i = 0; i < 10; i++)
sum += fooptr (drand48 ());
printf ("%lf\n", sum);
dlclose (handle);
}
else
fprintf (stderr, "can't open shared object\n");
sleep (1);
}
return z;
}
all: libfoo.so main
libfoo.so: libfoo.c
gcc -fPIC -O0 -g3 -shared -o libfoo.so libfoo.c -lm
main: main.c
gcc -O0 -g3 -o main main.c -ldl
clean:
rm -f libfoo.so main
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