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[thirdparty/glibc.git] / sysdeps / s390 / s390-64 / dl-trampoline.S

diff --git a/sysdeps/s390/s390-64/dl-trampoline.S b/sysdeps/s390/s390-64/dl-trampoline.S
index b49c68108d0b34a93e83fd480d031857874b3b20..87c6d50ced84a0ebc572faaf67a780ec3a461746 100644 (file)
--- a/sysdeps/s390/s390-64/dl-trampoline.S
+++ b/sysdeps/s390/s390-64/dl-trampoline.S
@@ -1,5 +1,5 @@
-/* PLT trampolines.  s390 version.
-   Copyright (C) 2005 Free Software Foundation, Inc.
+/* PLT trampolines.  s390x version.
+   Copyright (C) 2005-2014 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -13,16 +13,15 @@
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
 
 /* The PLT stubs will call _dl_runtime_resolve/_dl_runtime_profile
  * with the following linkage:
  *   r2 - r6 : parameter registers
  *   f0, f2, f4, f6 : floating point parameter registers
- *   24(r15), 28(r15) : PLT arguments PLT1, PLT2
- *   96(r15) : additional stack parameters
+ *   48(r15), 56(r15) : PLT arguments PLT1, PLT2
+ *   160(r15) : additional stack parameters
  * The normal clobber rules for function calls apply:
  *   r0 - r5 : call clobbered
  *   r6 - r13 :         call saved
@@ -40,21 +39,21 @@
        cfi_startproc
        .align 16
 _dl_runtime_resolve:
-       stmg   2,5,64(15)       # save registers
-       stg    14,96(15)
+       stmg   %r2,%r5,64(15)   # save call-clobbered argument registers
+       stg    %r14,96(15)
        cfi_offset (r14, -64)
-       lgr    0,15             # create stack frame
-       aghi   15,-160
+       lgr    %r0,%r15
+       aghi   %r15,-160        # create stack frame
        cfi_adjust_cfa_offset (160)
-       stg    0,0(15)
-       lmg    2,3,208(15)      # load args saved by PLT
-       brasl  14,_dl_fixup     # call fixup
-       lgr    1,2              # function addr returned in r2
-       aghi   15,160           # remove stack frame
+       stg    %r0,0(%r15)      # write backchain
+       lmg    %r2,%r3,208(%r15)# load args saved by PLT
+       brasl  %r14,_dl_fixup   # call fixup
+       lgr    %r1,%r2          # function addr returned in r2
+       aghi   %r15,160         # remove stack frame
        cfi_adjust_cfa_offset (-160)
-       lg     14,96(15)        # restore registers
-       lmg    2,5,64(15)
-       br     1
+       lg     %r14,96(15)      # restore registers
+       lmg    %r2,%r5,64(15)
+       br     %r1
        cfi_endproc
        .size _dl_runtime_resolve, .-_dl_runtime_resolve
 
@@ -65,13 +64,12 @@ _dl_runtime_resolve:
        cfi_startproc
        .align 16
 _dl_runtime_profile:
-       stmg   %r2,%r6,64(%r15)         # save registers
-       std    %f0,104(%r15)
-       std    %f2,112(%r15)
+       stmg   %r2,%r6,64(%r15)         # save call-clobbered arg regs
+       std    %f0,104(%r15)            # + r6 needed as arg for
+       std    %f2,112(%r15)            #  _dl_profile_fixup
        std    %f4,120(%r15)
        std    %f6,128(%r15)
-       stg    %r6,16(%r15)
-       stg    %r12,24(%r15)
+       stg    %r12,24(%r15)            # r12 is used as backup of r15
        stg    %r14,32(%r15)
        cfi_offset (r6, -96)
        cfi_offset (f0, -56)
@@ -80,10 +78,10 @@ _dl_runtime_profile:
        cfi_offset (f6, -32)
        cfi_offset (r12, -136)
        cfi_offset (r14, -128)
-       lgr    %r12,%r15                # create stack frame
+       lgr    %r12,%r15                # backup stack pointer
        cfi_def_cfa_register (12)
-       aghi   %r15,-160
-       stg    %r12,0(%r15)
+       aghi   %r15,-160                # create stack frame
+       stg    %r12,0(%r15)             # save backchain
        lmg    %r2,%r3,48(%r12)         # load arguments saved by PLT
        lgr    %r4,%r14                 # return address as third parameter
        la     %r5,64(%r12)             # pointer to struct La_s390_32_regs
@@ -93,18 +91,19 @@ _dl_runtime_profile:
        lg     %r0,40(%r12)             # load framesize
        ltgr   %r0,%r0
        jnm    1f
-       lmg    %r2,%r6,64(%r12)
-       ld     %f0,104(%r12)
-       ld     %f2,112(%r12)
+
+       lmg    %r2,%r6,64(%r12)         # framesize < 0 means no pltexit call
+       ld     %f0,104(%r12)            # so we can do a tail call without
+       ld     %f2,112(%r12)            # copying the arg overflow area
        ld     %f4,120(%r12)
        ld     %f6,128(%r12)
-       basr   %r14,%r1                 # call resolved function
-0:     lgr    %r15,%r12                # remove stack frame
+
+       lgr    %r15,%r12                # remove stack frame
        cfi_def_cfa_register (15)
        lg     %r14,32(%r15)            # restore registers
        lg     %r12,24(%r15)
-       lg     %r6,16(%r15)
-       br     %r14
+       br     %r1                      # tail-call to resolved function
+
        cfi_def_cfa_register (12)
 1:     jz     4f                       # framesize == 0 ?
        aghi   %r0,7                    # align framesize to 8
@@ -119,7 +118,7 @@ _dl_runtime_profile:
        la     %r3,8(%r3)
        brctg  %r0,3b
 4:     lmg    %r2,%r6,64(%r12)         # load register parameters
-       ld     %f0,104(%r12)
+       ld     %f0,104(%r12)            # restore call-clobbered arg regs
        ld     %f2,112(%r12)
        ld     %f4,120(%r12)
        ld     %f6,128(%r12)
@@ -130,7 +129,13 @@ _dl_runtime_profile:
        la     %r4,32(%r12)             # pointer to struct La_s390_32_regs
        la     %r5,72(%r12)             # pointer to struct La_s390_32_retval
        brasl  %r14,_dl_call_pltexit
-       j      0b
+
+       lgr    %r15,%r12                # remove stack frame
+       cfi_def_cfa_register (15)
+       lg     %r14,32(%r15)            # restore registers
+       lg     %r12,24(%r15)
+       br     %r14
+
        cfi_endproc
        .size _dl_runtime_profile, .-_dl_runtime_profile
 #endif