[uclibc-ng-devel] [PATCH] xtensa: fix _dl_tlsdesc_dynamic

There are multiple errors in _dl_tlsdesc_dynamic: - the reference C implementation should return pointer to the thread-local variable, not offset from the thread pointer, because the xtensa ABI expects TLSDESC_FN to return pointer to the TLS variable; - addx8 used for indexing into dtv has its second and third registers in wrong order, the index must be multiplied by 8, not the base; - the same addx8 uses wrong base: instead of dtv it adds the offset to the threadptr; - the return value in the fast path is calculated as td->tlsinfo.ti_offset - __builtin_thread_pointer, not what was intended; - both fast and slow paths should not subtract __builtin_thread_pointer from the result. Signed-off-by: Max Filippov <jcmvbkbc(a)gmail.com> --- ldso/ldso/xtensa/dl-tlsdesc.S | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/ldso/ldso/xtensa/dl-tlsdesc.S b/ldso/ldso/xtensa/dl-tlsdesc.S index 6f417f61a98b..426f2180b3c0 100644 --- a/ldso/ldso/xtensa/dl-tlsdesc.S +++ b/ldso/ldso/xtensa/dl-tlsdesc.S @@ -39,7 +39,7 @@ END (_dl_tlsdesc_return) The assembly code that follows is a rendition of the following C code, hand-optimized a little bit. - ptrdiff_t + void * _dl_tlsdesc_dynamic(struct tlsdesc_dynamic_arg *td) { dtv_t *dtv = (dtv_t *)THREAD_DTV(); @@ -47,8 +47,8 @@ END (_dl_tlsdesc_return) && dtv[td->tlsinfo.ti_module].pointer.val != TLS_DTV_UNALLOCATED) return dtv[td->tlsinfo.ti_module].pointer.val - + td->tlsinfo.ti_offset - __builtin_thread_pointer(); - return __tls_get_addr (&td->tlsinfo) - __builtin_thread_pointer(); + + td->tlsinfo.ti_offset; + return __tls_get_addr (&td->tlsinfo); } */ @@ -65,33 +65,30 @@ HIDDEN_ENTRY (_dl_tlsdesc_dynamic) /* && dtv[td->tlsinfo.ti_module].pointer.val != TLS_DTV_UNALLOCATED) */ l32i a6, a2, TLSDESC_MODID - addx8 a6, a3, a6 + addx8 a6, a6, a4 l32i a6, a6, 0 beqi a6, -1, .Lslow /* return dtv[td->tlsinfo.ti_module].pointer.val - + td->tlsinfo.ti_offset - __builtin_thread_pointer(); */ - l32i a6, a2, TLSDESC_MODOFF - sub a2, a6, a3 + + td->tlsinfo.ti_offset; */ + l32i a5, a2, TLSDESC_MODOFF + add a2, a6, a5 abi_ret - /* return __tls_get_addr (&td->tlsinfo) - __builtin_thread_pointer(); */ + /* return __tls_get_addr (&td->tlsinfo); */ .Lslow: #if defined(__XTENSA_WINDOWED_ABI__) mov a6, a2 movi a4, __tls_get_addr callx4 a4 - sub a2, a6, a3 + mov a2, a6 retw #elif defined(__XTENSA_CALL0_ABI__) addi a1, a1, -16 s32i a0, a1, 0 - s32i a3, a1, 4 movi a0, __tls_get_addr callx0 a0 - l32i a3, a1, 4 l32i a0, a1, 0 - sub a2, a2, a3 addi a1, a1, 16 ret #else -- 2.1.4