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glibc/sysdeps/powerpc/powerpc64/__longjmp-common.S
Alan Modra d6efcc118e powerpc64: Use medium model toc accesses throughout 
The PowerPC64 linker edits medium model toc-indirect code to toc-pointer
relative:
	addis r9,r2,tc_entry_for_var@toc@ha
	ld r9,tc_entry_for_var@toc@l(r9)
becomes
	addis r9,r2,(var-.TOC.)@ha
	addi r9,r9,(var-.TOC.)@l
when "var" is known to be local to the binary.  This isn't done for
small-model toc-indirect code, because "var" is almost guaranteed to
be too far away from .TOC. for a 16-bit signed offset.  And, because
the analysis of which .toc entry can be removed becomes much more
complicated in objects that mix code models, they aren't removed if
any small-model toc sequence appears in an object file.

Unfortunately, glibc's build of ld.so smashes the needed objects
together in a ld -r linking stage.  This means the GOT/TOC is left
with a whole lot of relative relocations which is untidy, but in
itself is not a serious problem.  However, static-pie on powerpc64
bombs due to a segfault caused by one of the small-model accesses
before _dl_relocate_static_pie.  (The very first one in rcrt1.o
passing start_addresses in r8 to __libc_start_main.)

So this patch makes all the toc/got accesses in assembly medium code
model, and a couple of functions hidden.  By itself this is not
enough to give us working static-pie, but it is useful in isolation to
enable better linker optimisation.

There's a serious problem in libgcc too.  libgcc ifuncs access the
AT_HWCAP words stored in the tcb with an offset from the thread
pointer (r13), but r13 isn't set at the time _dl_relocate_static_pie.
A followup patch will fix that.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
2022-04-10 08:33:06 +09:30

183 lines
4.7 KiB
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/* longjmp for PowerPC64.
Copyright (C) 1995-2022 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
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <stap-probe.h>
#define _ASM
#define _SETJMP_H
#ifdef __NO_VMX__
# include <novmxsetjmp.h>
#else
# include <jmpbuf-offsets.h>
#endif
#ifndef __NO_VMX__
.section ".toc","aw"
.LC__dl_hwcap:
# ifdef SHARED
# if IS_IN (rtld)
/* Inside ld.so we use the local alias to avoid runtime GOT
relocations. */
.tc _rtld_local_ro[TC],_rtld_local_ro
# else
.tc _rtld_global_ro[TC],_rtld_global_ro
# endif
# else
.tc _dl_hwcap[TC],_dl_hwcap
# endif
.section ".text"
#endif
.machine "altivec"
ENTRY (__longjmp)
CALL_MCOUNT 2
#ifndef __NO_VMX__
addis r5,r2,.LC__dl_hwcap@toc@ha
ld r5,.LC__dl_hwcap@toc@l(r5)
# ifdef SHARED
/* Load _rtld-global._dl_hwcap. */
ld r5,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r5)
# else
/* Load extern _dl_hwcap. */
ld r5,0(r5)
# endif
andis. r5,r5,(PPC_FEATURE_HAS_ALTIVEC >> 16)
beq L(no_vmx)
la r5,((JB_VRS)*8)(3)
andi. r6,r5,0xf
lwz r0,((JB_VRSAVE)*8)(3) /* 32-bit VRSAVE. */
mtspr VRSAVE,r0
beq+ L(aligned_restore_vmx)
addi r6,r5,16
lvsl v0,0,r5
lvx v1,0,r5
addi r5,r5,32
lvx v21,0,r6
vperm v20,v1,v21,v0
# define load_misaligned_vmx_lo_loaded(loadvr,lovr,shiftvr,loadgpr,addgpr) \
addi addgpr,addgpr,32; \
lvx lovr,0,loadgpr; \
vperm loadvr,loadvr,lovr,shiftvr;
load_misaligned_vmx_lo_loaded(v21,v22,v0,r5,r6)
load_misaligned_vmx_lo_loaded(v22,v23,v0,r6,r5)
load_misaligned_vmx_lo_loaded(v23,v24,v0,r5,r6)
load_misaligned_vmx_lo_loaded(v24,v25,v0,r6,r5)
load_misaligned_vmx_lo_loaded(v25,v26,v0,r5,r6)
load_misaligned_vmx_lo_loaded(v26,v27,v0,r6,r5)
load_misaligned_vmx_lo_loaded(v27,v28,v0,r5,r6)
load_misaligned_vmx_lo_loaded(v28,v29,v0,r6,r5)
load_misaligned_vmx_lo_loaded(v29,v30,v0,r5,r6)
load_misaligned_vmx_lo_loaded(v30,v31,v0,r6,r5)
lvx v1,0,r5
vperm v31,v31,v1,v0
b L(no_vmx)
L(aligned_restore_vmx):
addi r6,r5,16
lvx v20,0,r5
addi r5,r5,32
lvx v21,0,r6
addi r6,r6,32
lvx v22,0,r5
addi r5,r5,32
lvx v23,0,r6
addi r6,r6,32
lvx v24,0,r5
addi r5,r5,32
lvx v25,0,r6
addi r6,r6,32
lvx v26,0,r5
addi r5,r5,32
lvx v27,0,r6
addi r6,r6,32
lvx v28,0,r5
addi r5,r5,32
lvx v29,0,r6
addi r6,r6,32
lvx v30,0,r5
lvx v31,0,r6
L(no_vmx):
#endif
#if defined PTR_DEMANGLE || defined CHECK_SP
ld r22,(JB_GPR1*8)(r3)
#else
ld r1,(JB_GPR1*8)(r3)
#endif
#ifdef PTR_DEMANGLE
# ifdef CHECK_SP
PTR_DEMANGLE3 (r22, r22, r25)
# else
PTR_DEMANGLE3 (r1, r22, r25)
# endif
#endif
#ifdef CHECK_SP
CHECK_SP (r22)
mr r1,r22
#endif
ld r2,(JB_GPR2*8)(r3)
ld r0,(JB_LR*8)(r3)
ld r14,((JB_GPRS+0)*8)(r3)
lfd fp14,((JB_FPRS+0)*8)(r3)
ld r15,((JB_GPRS+1)*8)(r3)
lfd fp15,((JB_FPRS+1)*8)(r3)
ld r16,((JB_GPRS+2)*8)(r3)
lfd fp16,((JB_FPRS+2)*8)(r3)
ld r17,((JB_GPRS+3)*8)(r3)
lfd fp17,((JB_FPRS+3)*8)(r3)
ld r18,((JB_GPRS+4)*8)(r3)
lfd fp18,((JB_FPRS+4)*8)(r3)
ld r19,((JB_GPRS+5)*8)(r3)
lfd fp19,((JB_FPRS+5)*8)(r3)
ld r20,((JB_GPRS+6)*8)(r3)
lfd fp20,((JB_FPRS+6)*8)(r3)
#ifdef PTR_DEMANGLE
PTR_DEMANGLE2 (r0, r25)
#endif
/* longjmp/longjmp_target probe expects longjmp first argument (8@3),
second argument (-4@4), and target address (8@0), respectively. */
LIBC_PROBE (longjmp, 3, 8@3, -4@4, 8@0)
mtlr r0
std r2,FRAME_TOC_SAVE(r1) /* Restore the TOC save area. */
ld r21,((JB_GPRS+7)*8)(r3)
lfd fp21,((JB_FPRS+7)*8)(r3)
ld r22,((JB_GPRS+8)*8)(r3)
lfd fp22,((JB_FPRS+8)*8)(r3)
lwz r5,((JB_CR*8)+4)(r3) /* 32-bit CR. */
ld r23,((JB_GPRS+9)*8)(r3)
lfd fp23,((JB_FPRS+9)*8)(r3)
ld r24,((JB_GPRS+10)*8)(r3)
lfd fp24,((JB_FPRS+10)*8)(r3)
ld r25,((JB_GPRS+11)*8)(r3)
lfd fp25,((JB_FPRS+11)*8)(r3)
mtcrf 0xFF,r5
ld r26,((JB_GPRS+12)*8)(r3)
lfd fp26,((JB_FPRS+12)*8)(r3)
ld r27,((JB_GPRS+13)*8)(r3)
lfd fp27,((JB_FPRS+13)*8)(r3)
ld r28,((JB_GPRS+14)*8)(r3)
lfd fp28,((JB_FPRS+14)*8)(r3)
ld r29,((JB_GPRS+15)*8)(r3)
lfd fp29,((JB_FPRS+15)*8)(r3)
ld r30,((JB_GPRS+16)*8)(r3)
lfd fp30,((JB_FPRS+16)*8)(r3)
ld r31,((JB_GPRS+17)*8)(r3)
lfd fp31,((JB_FPRS+17)*8)(r3)
LIBC_PROBE (longjmp_target, 3, 8@3, -4@4, 8@0)
mr r3,r4
blr
END (__longjmp)
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