Hi, I'm using a GNU/Linux on an Intel 32bit x86. I think that I might be digging too deep. There shouldn't be any problem with the gs segment or whatever it points to. The application is a C program that dynamically loads (using dlopen()) C++ libraries. Do I need to set -ftls-model=global-dynamic when compiling the various C++ libraries so TLS works correctly? (gdb) disas __cxa_get_globals Dump of assembler code for function __cxa_get_globals: 0xf6f536d0 <__cxa_get_globals+0>: push %ebp 0xf6f536d1 <__cxa_get_globals+1>: mov %esp,%ebp 0xf6f536d3 <__cxa_get_globals+3>: push %ebx 0xf6f536d4 <__cxa_get_globals+4>: call 0xf6ee8f07 <pthread_join+247> 0xf6f536d9 <__cxa_get_globals+9>: add $0x3591b,%ebx 0xf6f536df <__cxa_get_globals+15>: lea -0x56c(,%ebx,1),%eax 0xf6f536e6 <__cxa_get_globals+22>: call 0xf6ee7730 <___tls_get_addr@plt> 0xf6f536eb <__cxa_get_globals+27>: pop %ebx 0xf6f536ec <__cxa_get_globals+28>: pop %ebp 0xf6f536ed <__cxa_get_globals+29>: ret Now in order to get eax's value before the call to ___tls_get_attr() I do: 0xf6f536d9 + 0x3591b = 0xf6f88ff4 0xf6f88ff4 - 0x56c = 0xf6f88a88 Can this value help me locate which tls value is accessed here? Can I find it with readelf or objdump? Thanks, Saul On Wed, Jan 16, 2013 at 5:59 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > On Wed, Jan 16, 2013 at 12:08 PM, Saul Tamari <stamari@xxxxxxxxx> wrote: >> >> Is ___tls_get_addr_internal() compiled from C source code or is it >> generated directly in assembly code? >> Where can I find the C source code that was used to generate >> ___tls_get_addr_internal ? > > __tls_get_addr is provided by your C library. I don't think you > mentioned what system you are using, but if it is a GNU/Linux system > then __tls_get_addr defined by glibc. I'm not sure quite where > __tls_get_addr_internal comes in. __tls_get_addr is defined in > elf/dl-tls.c in the glibc sources. You seem to be using 32-bit x86; > the interesting 32-bit x86 code is in nptl/sysdeps/i386/tls.h. > > It does indeed use %gs. You can't change %gs yourself if your program > uses TLS variables. > > Ian
