From: Alan Modra <amodra@gmail.com>
To: libc-alpha@sourceware.org
Cc: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Subject: [PowerPC64] Use medium model toc accesses throughout
Date: Sun, 23 Jan 2022 23:12:13 +1030 [thread overview]
Message-ID: <Ye1NJQwEpe7AyNYD@squeak.grove.modra.org> (raw)
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 anyway 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
runs, and I'm loathe to try calling init_tls early. A better approach
that might work is to fake r13 so that _dl_hwcap is at the expected
offset where we'd normally find the tcb hwcap words.
Tested for regressions with a powerpc64le-linux build and test run.
OK to apply?
diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
index 4d71b9e102..5f629e1e0f 100644
--- a/sysdeps/powerpc/powerpc64/__longjmp-common.S
+++ b/sysdeps/powerpc/powerpc64/__longjmp-common.S
@@ -47,12 +47,14 @@
ENTRY (__longjmp)
CALL_MCOUNT 2
#ifndef __NO_VMX__
- ld r5,.LC__dl_hwcap@toc(r2)
+ 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)
+ ld r5,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r5)
# else
- ld r5,0(r5) /* Load extern _dl_hwcap. */
+ /* Load extern _dl_hwcap. */
+ ld r5,0(r5)
# endif
andis. r5,r5,(PPC_FEATURE_HAS_ALTIVEC >> 16)
beq L(no_vmx)
diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
index a505998351..eb41c85280 100644
--- a/sysdeps/powerpc/powerpc64/dl-machine.h
+++ b/sysdeps/powerpc/powerpc64/dl-machine.h
@@ -175,9 +175,12 @@ BODY_PREFIX "_dl_start_user:\n" \
/* the address of _start in r30. */ \
" mr 30,3\n" \
/* &_dl_argc in 29, &_dl_argv in 27, and _dl_loaded in 28. */ \
-" ld 28,.LC__rtld_local@toc(2)\n" \
-" ld 29,.LC__dl_argc@toc(2)\n" \
-" ld 27,.LC__dl_argv@toc(2)\n" \
+" addis 28,2,.LC__rtld_local@toc@ha\n" \
+" ld 28,.LC__rtld_local@toc@l(28)\n" \
+" addis 29,2,.LC__dl_argc@toc@ha\n" \
+" ld 29,.LC__dl_argc@toc@l(29)\n" \
+" addis 27,2,.LC__dl_argv@toc@ha\n" \
+" ld 27,.LC__dl_argv@toc@l(27)\n" \
/* _dl_init (_dl_loaded, _dl_argc, _dl_argv, _dl_argv+_dl_argc+1). */ \
" ld 3,0(28)\n" \
" lwa 4,0(29)\n" \
@@ -204,7 +207,8 @@ BODY_PREFIX "_dl_start_user:\n" \
" addi 6,6,8\n" \
/* Pass a termination function pointer (in this case _dl_fini) in \
r7. */ \
-" ld 7,.LC__dl_fini@toc(2)\n" \
+" addis 7,2,.LC__dl_fini@toc@ha\n" \
+" ld 7,.LC__dl_fini@toc@l(7)\n" \
/* Pass the stack pointer in r1 (so far so good), pointing to a NULL \
value. This lets our startup code distinguish between a program \
linked statically, which linux will call with argc on top of the \
diff --git a/sysdeps/powerpc/powerpc64/dl-trampoline.S b/sysdeps/powerpc/powerpc64/dl-trampoline.S
index 23debc2faf..45b821607b 100644
--- a/sysdeps/powerpc/powerpc64/dl-trampoline.S
+++ b/sysdeps/powerpc/powerpc64/dl-trampoline.S
@@ -32,6 +32,7 @@
because gcc as of 2010/05 doesn't allocate a proper stack frame for
a function that makes no calls except for __tls_get_addr and we
might be here resolving the __tls_get_addr call. */
+ .hidden _dl_runtime_resolve
#define INT_PARMS FRAME_MIN_SIZE
ENTRY (_dl_runtime_resolve, 4)
stdu r1,-FRAME_SIZE(r1)
@@ -195,6 +196,7 @@ END(_dl_runtime_resolve)
parm1 (r3) and the index (r0) needs to be converted to an offset
(index * 24) in parm2 (r4). */
#ifndef PROF
+ .hidden _dl_profile_resolve
ENTRY (_dl_profile_resolve, 4)
/* Spill r30, r31 to preserve the link_map* and reloc_addr, in case we
need to call _dl_audit_pltexit. */
@@ -225,12 +227,14 @@ ENTRY (_dl_profile_resolve, 4)
std r9,INT_PARMS+48(r1)
std r10,INT_PARMS+56(r1)
std r8,CALLING_SP(r1)
- ld r12,.LC__dl_hwcap@toc(r2)
+ addis r12,r2,.LC__dl_hwcap@toc@ha
+ ld r12,.LC__dl_hwcap@toc@l(r12)
#ifdef SHARED
/* Load _rtld_local_ro._dl_hwcap. */
ld r12,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r12)
#else
- ld r12,0(r12) /* Load extern _dl_hwcap. */
+ /* Load extern _dl_hwcap. */
+ ld r12,0(r12)
#endif
andis. r0,r12,(PPC_FEATURE_HAS_ALTIVEC >> 16)
beq L(saveFP)
diff --git a/sysdeps/powerpc/powerpc64/setjmp-common.S b/sysdeps/powerpc/powerpc64/setjmp-common.S
index 41812e3427..19e76d59ee 100644
--- a/sysdeps/powerpc/powerpc64/setjmp-common.S
+++ b/sysdeps/powerpc/powerpc64/setjmp-common.S
@@ -132,12 +132,14 @@ JUMPTARGET(GLUE(__sigsetjmp_symbol,_ent)):
std r31,((JB_GPRS+17)*8)(3)
stfd fp31,((JB_FPRS+17)*8)(3)
#ifndef __NO_VMX__
- ld r6,.LC__dl_hwcap@toc(r2)
+ addis r6,r2,.LC__dl_hwcap@toc@ha
+ ld r6,.LC__dl_hwcap@toc@l(r6)
# ifdef SHARED
/* Load _rtld-global._dl_hwcap. */
- ld r6,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r6)
+ ld r6,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r6)
# else
- ld r6,0(r6) /* Load extern _dl_hwcap. */
+ /* Load extern _dl_hwcap. */
+ ld r6,0(r6)
# endif
andis. r6,r6,(PPC_FEATURE_HAS_ALTIVEC >> 16)
beq L(no_vmx)
diff --git a/sysdeps/powerpc/powerpc64/start.S b/sysdeps/powerpc/powerpc64/start.S
index 4319dc8d3e..244d9da07b 100644
--- a/sysdeps/powerpc/powerpc64/start.S
+++ b/sysdeps/powerpc/powerpc64/start.S
@@ -74,7 +74,8 @@ ENTRY (_start)
/* put the address of start_addresses in r8... **
** PPC64 ABI uses R13 for thread local, so we leave it alone */
- ld r8,.L01@toc(r2)
+ addis r8,r2,.L01@toc@ha
+ ld r8,.L01@toc@l(r8)
/* and continue in libc-start, in glibc. */
b JUMPTARGET(__libc_start_main)
diff --git a/sysdeps/powerpc/powerpc64/sysdep.h b/sysdeps/powerpc/powerpc64/sysdep.h
index 3fec06e0df..011068b290 100644
--- a/sysdeps/powerpc/powerpc64/sysdep.h
+++ b/sysdeps/powerpc/powerpc64/sysdep.h
@@ -469,14 +469,16 @@ LT_LABELSUFFIX(name,_name_end): ; \
.tc _rtld_global_ro[TC],_rtld_global_ro
# endif
# define __GLRO(rOUT, var, offset) \
- ld rOUT,.LC__ ## var@toc(r2); \
+ addis rOUT,r2,.LC__ ## var@toc@ha; \
+ ld rOUT,.LC__ ## var@toc@l(rOUT); \
lwz rOUT,offset(rOUT)
#else
# define __GLRO_DEF(var) \
.LC__ ## var: \
.tc _ ## var[TC],_ ## var
# define __GLRO(rOUT, var, offset) \
- ld rOUT,.LC__ ## var@toc(r2); \
+ addis rOUT,r2,.LC__ ## var@toc@ha; \
+ ld rOUT,.LC__ ## var@toc@l(rOUT); \
lwz rOUT,0(rOUT)
#endif
--
Alan Modra
Australia Development Lab, IBM
next reply other threads:[~2022-01-23 12:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-23 12:42 Alan Modra [this message]
2022-01-24 3:47 ` [PATCH 2/5] [PowerPC64] Set up thread register for _dl_relocate_static_pie Alan Modra
2022-02-16 23:02 ` Paul E Murphy
2022-02-19 0:49 ` Alan Modra
2022-01-24 3:50 ` [PATCH 3/5] [PowerPC] Relocate stinfo->main Alan Modra
2022-01-24 4:48 ` H.J. Lu
2022-01-24 6:51 ` Alan Modra
2022-01-24 3:52 ` [PATCH 4/5] Constify a variable in dl_vdso_vsym Alan Modra
2022-01-24 4:06 ` [PATCH 5/5] Enable static-pie on powerpc64 Alan Modra
2022-01-27 18:39 ` Florian Weimer
2022-01-28 8:45 ` Alan Modra
2022-01-28 17:48 ` [PowerPC64] Use medium model toc accesses throughout Paul E Murphy
2022-01-29 1:24 ` Alan Modra
2022-02-28 6:40 ` [PATCH v2 0/4] PowerPC64 static-pie Alan Modra
2022-02-28 6:40 ` [PATCH v2 1/4] powerpc64: Use medium model toc accesses throughout Alan Modra
2022-04-08 22:28 ` Tulio Magno Quites Machado Filho
2022-02-28 6:40 ` [PATCH v2 2/4] powerpc64: Set up thread register for _dl_relocate_static_pie Alan Modra
2022-04-08 22:28 ` Tulio Magno Quites Machado Filho
2022-02-28 6:40 ` [PATCH v2 3/4] powerpc: Relocate stinfo->main Alan Modra
2022-04-08 22:32 ` Tulio Magno Quites Machado Filho
2022-02-28 6:40 ` [PATCH v2 4/4] powerpc64: Enable static-pie Alan Modra
2022-04-08 22:49 ` Tulio Magno Quites Machado Filho
2022-04-14 1:16 ` Alan Modra
2022-04-14 3:42 ` Fangrui Song
2022-04-20 7:21 ` [PATCH v3] " Alan Modra
2022-03-04 12:48 ` [PATCH v2 0/4] PowerPC64 static-pie Alan Modra
2022-04-08 8:06 ` Alan Modra
2022-04-09 0:14 ` Fangrui Song
2022-04-14 0:33 ` Alan Modra
2022-04-14 1:54 ` DT_RELR without libc.so dependency H.J. Lu
2022-04-14 3:43 ` Fangrui Song
2022-04-14 5:18 ` Alan Modra
2022-04-14 17:55 ` H.J. Lu
2022-04-08 22:27 ` [PATCH v2 0/4] PowerPC64 static-pie Tulio Magno Quites Machado Filho
2022-04-11 1:38 ` Alan Modra
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