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aix: 64 bit AIX TLS libpthread dependency.

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64bit XCOFF files will generated TLS access, with local-exec or
global-exec models, by an access to R13. Thus, there isn't
any reference to a TLS symbol.

The problem is that it allows programs with TLS to be compiled and
linked even without -pthread. Most of the time, it will result in
a segfault when trying to access a TLS variable. But sometimes, it
might create a memory corruption.

This patch forces a reference to __tls_get_addr() to ensure link
will fail without -pthread.

gcc/ChangeLog:
2021-08-11  Clément Chigot  <clement.chigot@atos.net>

	* config/rs6000/rs6000.c (xcoff_tls_exec_model_detected): New.
	(rs6000_legitimize_tls_address_aix): Use it.
	(rs6000_xcoff_file_end): Add ".ref __tls_get_addr" when
	xcoff_tls_exec_model_detected is true.
This commit is contained in:
Clément Chigot 2021-08-12 13:17:15 -04:00 committed by David Edelsohn
parent 882f1d58bf
commit 34ce7f7a9a
1 changed files with 13 additions and 1 deletions
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14
gcc/config/rs6000/rs6000.c
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@ -127,6 +127,9 @@ scalar_int_mode rs6000_pmode;
bool rs6000_passes_ieee128 = false;
#endif
/* Track use of r13 in 64bit AIX TLS. */
static bool xcoff_tls_exec_model_detected = false;
/* Generate the manged name (i.e. U10__float128) used in GCC 8.1, and not the
name used in current releases (i.e. u9__ieee128). */
static bool ieee128_mangling_gcc_8_1;
@ -9397,7 +9400,10 @@ rs6000_legitimize_tls_address_aix (rtx addr, enum tls_model model)
emit_insn (gen_tls_get_tpointer (tlsreg));
}
else
tlsreg = gen_rtx_REG (DImode, 13);
{
tlsreg = gen_rtx_REG (DImode, 13);
xcoff_tls_exec_model_detected = true;
}
/* Load the TOC value into temporary register. */
tmpreg = gen_reg_rtx (Pmode);
@ -21122,6 +21128,12 @@ rs6000_xcoff_file_end (void)
fputs (TARGET_32BIT
? "\t.long _section_.text\n" : "\t.llong _section_.text\n",
asm_out_file);
if (xcoff_tls_exec_model_detected)
{
/* Add a .ref to __tls_get_addr to force libpthread dependency. */
fputs ("\t.extern __tls_get_addr\n\t.ref __tls_get_addr\n", asm_out_file);
}
}
struct declare_alias_data