powerpc: Move cache line size to rtld_global_ro

GCC 10.0 enabled -fno-common by default and this started to point that
__cache_line_size had been implemented in 2 different places: loader and
libc.

In order to avoid this duplication, the libc variable has been removed
and the loader variable is moved to rtld_global_ro.

File sysdeps/unix/sysv/linux/powerpc/dl-auxv.h has been added in order
to reuse code for both static and dynamic linking scenarios.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

14 files changed, 275 insertions, 45 deletions

diff --git a/sysdeps/powerpc/Makefile b/sysdeps/powerpc/Makefile
index df45d348d2..d1c71a0ca4 100644
--- a/sysdeps/powerpc/Makefile
+++ b/sysdeps/powerpc/Makefile
@@ -14,6 +14,23 @@ mod-tlsopt-powerpc.so-no-z-defs = yes
 tests += tst-tlsopt-powerpc
 $(objpfx)tst-tlsopt-powerpc: $(objpfx)mod-tlsopt-powerpc.so
 
+tests-static += tst-cache-ppc-static
+tests-internal += tst-cache-ppc-static
+
+ifeq (yes,$(build-shared))
+modules-names += mod-cache-ppc
+tests += tst-cache-ppc tst-cache-ppc-static-dlopen
+tests-static += tst-cache-ppc-static-dlopen
+test-internal-extras += mod-cache-ppc
+
+mod-cache-ppc.so-no-z-defs = yes
+tst-cache-ppc-static-dlopen-ENV = LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)elf
+$(objpfx)tst-cache-ppc-static-dlopen: $(common-objpfx)dlfcn/libdl.a
+$(objpfx)tst-cache-ppc-static-dlopen.out: $(objpfx)mod-cache-ppc.so
+
+$(objpfx)tst-cache-ppc: $(objpfx)mod-cache-ppc.so
+endif
+
 ifneq (no,$(multi-arch))
 tests-static += tst-tlsifunc-static
 tests-internal += tst-tlsifunc-static
diff --git a/sysdeps/powerpc/dl-procinfo.c b/sysdeps/powerpc/dl-procinfo.c
index 2ae68c41f1..7a7d93dd0a 100644
--- a/sysdeps/powerpc/dl-procinfo.c
+++ b/sysdeps/powerpc/dl-procinfo.c
@@ -89,5 +89,22 @@ PROCINFO_CLASS const char _dl_powerpc_cap_flags[64][15]
 ,
 #endif
 
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+     ._dl_cache_line_size
+# else
+PROCINFO_CLASS int _dl_cache_line_size
+# endif
+# ifndef PROCINFO_DECL
+     = 0
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
+
+
 #undef PROCINFO_DECL
 #undef PROCINFO_CLASS
diff --git a/sysdeps/powerpc/mod-cache-ppc.c b/sysdeps/powerpc/mod-cache-ppc.c
new file mode 100644
index 0000000000..81fad52078
--- /dev/null
+++ b/sysdeps/powerpc/mod-cache-ppc.c
@@ -0,0 +1,45 @@
+/* Test if an executable can read from rtld_global_ro._dl_cache_line_size.
+   Copyright (C) 2020 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 <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <sys/auxv.h>
+#include <ldsodefs.h>
+#include <errno.h>
+
+/* errnop is required in order to work around BZ #20802.  */
+int
+test_cache (int *errnop)
+{
+  int cls1 = GLRO (dl_cache_line_size);
+  errno = *errnop;
+  uint64_t cls2 = getauxval (AT_DCACHEBSIZE);
+  *errnop = errno;
+
+  printf ("AT_DCACHEBSIZE      = %" PRIu64 " B\n", cls2);
+  printf ("_dl_cache_line_size = %d B\n", cls1);
+
+  if (cls1 != cls2)
+    {
+      printf ("error: _dl_cache_line_size != AT_DCACHEBSIZE\n");
+      return 1;
+    }
+
+  return 0;
+}
diff --git a/sysdeps/powerpc/powerpc32/a2/memcpy.S b/sysdeps/powerpc/powerpc32/a2/memcpy.S
index fe5dab847a..6f4d8a7b34 100644
--- a/sysdeps/powerpc/powerpc32/a2/memcpy.S
+++ b/sysdeps/powerpc/powerpc32/a2/memcpy.S
@@ -18,6 +18,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include <rtld-global-offsets.h>
 
 #define PREFETCH_AHEAD 4        /* no cache lines SRC prefetching ahead  */
 #define ZERO_AHEAD 2            /* no cache lines DST zeroing ahead  */
@@ -106,25 +107,23 @@ EALIGN (memcpy, 5, 0)
 L(dst_aligned):
 
 
-#ifdef SHARED
+#ifdef PIC
 	mflr    r0
-/* Establishes GOT addressability so we can load __cache_line_size
-   from static. This value was set from the aux vector during startup.  */
+/* Establishes GOT addressability so we can load the cache line size
+   from rtld_global_ro.  This value was set from the aux vector during
+   startup.  */
 	SETUP_GOT_ACCESS(r9,got_label)
-	addis   r9,r9,__cache_line_size-got_label@ha
-	lwz     r9,__cache_line_size-got_label@l(r9)
-	mtlr    r0
-#else
-/* Load __cache_line_size from static. This value was set from the
-   aux vector during startup.  */
-	lis     r9,__cache_line_size@ha
-	lwz     r9,__cache_line_size@l(r9)
+	addis	r9,r9,_GLOBAL_OFFSET_TABLE_-got_label@ha
+	addi	r9,r9,_GLOBAL_OFFSET_TABLE_-got_label@l
+	mtlr	r0
 #endif
+	__GLRO(r9, r9, _dl_cache_line_size,
+	       RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET)
 
 	cmplwi  cr5, r9, 0
 	bne+    cr5,L(cachelineset)
 
-/* __cache_line_size not set: generic byte copy without much optimization */
+/* Cache line size not set: generic byte copy without much optimization */
 	andi.	r0,r5,1		/* If length is odd copy one byte.  */
 	beq	L(cachelinenotset_align)
 	lbz	r7,0(r4)	/* Read one byte from source.  */
diff --git a/sysdeps/powerpc/powerpc32/dl-machine.c b/sysdeps/powerpc/powerpc32/dl-machine.c
index d5ea4b97f4..6090e60d3c 100644
--- a/sysdeps/powerpc/powerpc32/dl-machine.c
+++ b/sysdeps/powerpc/powerpc32/dl-machine.c
@@ -25,11 +25,6 @@
 #include <dl-machine.h>
 #include <_itoa.h>
 
-/* The value __cache_line_size is defined in dl-sysdep.c and is initialised
-   by _dl_sysdep_start via DL_PLATFORM_INIT.  */
-extern int __cache_line_size attribute_hidden;
-
-
 /* Stuff for the PLT.  */
 #define PLT_INITIAL_ENTRY_WORDS 18
 #define PLT_LONGBRANCH_ENTRY_WORDS 0
@@ -309,14 +304,14 @@ __elf_machine_runtime_setup (struct link_map *map, int lazy, int profile)
 
 	 Assumes that dcbst and icbi apply to lines of 16 bytes or
 	 more.  Current known line sizes are 16, 32, and 128 bytes.
-	 The following gets the __cache_line_size, when available.  */
+	 The following gets the cache line size, when available.  */
 
       /* Default minimum 4 words per cache line.  */
       int line_size_words = 4;
 
-      if (lazy && __cache_line_size != 0)
+      if (lazy && GLRO(dl_cache_line_size) != 0)
 	/* Convert bytes to words.  */
-	line_size_words = __cache_line_size / 4;
+	line_size_words = GLRO(dl_cache_line_size) / 4;
 
       size_modified = lazy ? rel_offset_words : 6;
       for (i = 0; i < size_modified; i += line_size_words)
diff --git a/sysdeps/powerpc/powerpc32/memset.S b/sysdeps/powerpc/powerpc32/memset.S
index 5f614c07d7..26c37f8a17 100644
--- a/sysdeps/powerpc/powerpc32/memset.S
+++ b/sysdeps/powerpc/powerpc32/memset.S
@@ -17,12 +17,13 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include <rtld-global-offsets.h>
 
 /* void * [r3] memset (void *s [r3], int c [r4], size_t n [r5]));
    Returns 's'.
 
    The memset is done in four sizes: byte (8 bits), word (32 bits),
-   32-byte blocks (256 bits) and __cache_line_size (128, 256, 1024 bits).
+   32-byte blocks (256 bits) and cache line size (128, 256, 1024 bits).
    There is a special case for setting whole cache lines to 0, which
    takes advantage of the dcbz instruction.  */
 
@@ -95,7 +96,7 @@ L(caligned):
 
 /* Check if we can use the special case for clearing memory using dcbz.
    This requires that we know the correct cache line size for this
-   processor.  Getting the __cache_line_size may require establishing GOT
+   processor.  Getting the cache line size may require establishing GOT
    addressability, so branch out of line to set this up.  */
 	beq	cr1, L(checklinesize)
 
@@ -230,26 +231,22 @@ L(medium_28t):
 	blr
 
 L(checklinesize):
-#ifdef SHARED
-	mflr	rTMP
 /* If the remaining length is less the 32 bytes then don't bother getting
    the cache line size.  */
 	beq	L(medium)
-/* Establishes GOT addressability so we can load __cache_line_size
-   from static. This value was set from the aux vector during startup.  */
+#ifdef PIC
+	mflr	rTMP
+/* Establishes GOT addressability so we can load the cache line size
+   from rtld_global_ro. This value was set from the aux vector during
+   startup.  */
 	SETUP_GOT_ACCESS(rGOT,got_label)
-	addis	rGOT,rGOT,__cache_line_size-got_label@ha
-	lwz	rCLS,__cache_line_size-got_label@l(rGOT)
+	addis	rGOT,rGOT,_GLOBAL_OFFSET_TABLE_-got_label@ha
+	addi	rGOT,rGOT,_GLOBAL_OFFSET_TABLE_-got_label@l
 	mtlr	rTMP
-#else
-/* Load __cache_line_size from static. This value was set from the
-   aux vector during startup.  */
-	lis	rCLS,__cache_line_size@ha
-/* If the remaining length is less the 32 bytes then don't bother getting
-   the cache line size.  */
-	beq	L(medium)
-	lwz	rCLS,__cache_line_size@l(rCLS)
 #endif
+/* Load rtld_global_ro._dl_cache_line_size.  */
+	__GLRO(rCLS, rGOT, _dl_cache_line_size,
+	       RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET)
 
 /* If the cache line size was not set then goto to L(nondcbz), which is
    safe for any cache line size.  */
diff --git a/sysdeps/powerpc/powerpc32/sysdep.h b/sysdeps/powerpc/powerpc32/sysdep.h
index ceed9ef158..0dee5f2757 100644
--- a/sysdeps/powerpc/powerpc32/sysdep.h
+++ b/sysdeps/powerpc/powerpc32/sysdep.h
@@ -157,4 +157,30 @@ GOT_LABEL:			;					      \
 /* Label in text section.  */
 #define C_TEXT(name) name
 
+/* Read the value of member from rtld_global_ro.  */
+#ifdef PIC
+# ifdef SHARED
+#  if IS_IN (rtld)
+/* Inside ld.so we use the local alias to avoid runtime GOT
+   relocations.  */
+#   define __GLRO(rOUT, rGOT, member, offset)				\
+	lwz     rOUT,_rtld_local_ro@got(rGOT);				\
+	lwz     rOUT,offset(rOUT)
+#  else
+#   define __GLRO(rOUT, rGOT, member, offset)				\
+	lwz     rOUT,_rtld_global_ro@got(rGOT);				\
+	lwz     rOUT,offset(rOUT)
+#  endif
+# else
+#  define __GLRO(rOUT, rGOT, member, offset)				\
+	lwz     rOUT,member@got(rGOT);					\
+	lwz     rOUT,0(rOUT)
+# endif
+#else
+/* Position-dependent code does not require access to the GOT.  */
+# define __GLRO(rOUT, rGOT, member, offset)				\
+	lis     rOUT,(member+LOWORD)@ha					\
+	lwz     rOUT,(member+LOWORD)@l(rOUT)
+#endif	/* PIC */
+
 #endif	/* __ASSEMBLER__ */
diff --git a/sysdeps/powerpc/powerpc64/a2/memcpy.S b/sysdeps/powerpc/powerpc64/a2/memcpy.S
index 0e3c435f3c..1162cc2207 100644
--- a/sysdeps/powerpc/powerpc64/a2/memcpy.S
+++ b/sysdeps/powerpc/powerpc64/a2/memcpy.S
@@ -18,6 +18,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include <rtld-global-offsets.h>
 
 #ifndef MEMCPY
 # define MEMCPY memcpy
@@ -27,8 +28,9 @@
 #define ZERO_AHEAD 2            /* no cache lines DST zeroing ahead  */
 
 	.section        ".toc","aw"
-.LC0:
-	.tc __cache_line_size[TC],__cache_line_size
+__GLRO_DEF(dl_cache_line_size)
+
+
 	.section        ".text"
 	.align 2
 
@@ -55,10 +57,11 @@ ENTRY (MEMCPY, 5)
 	*/
 
 	neg     r8,r3           /* LS 4 bits = # bytes to 8-byte dest bdry  */
-	ld      r9,.LC0@toc(r2) /* Get cache line size (part 1) */
+	/* Get the cache line size.  */
+	__GLRO (r9, dl_cache_line_size,
+		RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET)
 	clrldi  r8,r8,64-4      /* align to 16byte boundary  */
 	sub     r7,r4,r3        /* compute offset to src from dest */
-	lwz     r9,0(r9)        /* Get cache line size (part 2) */
 	cmpldi  cr0,r8,0        /* Were we aligned on a 16 byte bdy? */
 	addi    r10,r9,-1       /* Cache line mask */
 	beq+    L(dst_aligned)
@@ -121,7 +124,7 @@ L(dst_aligned):
 	cmpdi	cr0,r9,0	/* Cache line size set? */
 	bne+	cr0,L(cachelineset)
 
-/* __cache_line_size not set: generic byte copy without much optimization */
+/* Cache line size not set: generic byte copy without much optimization */
 	clrldi.	r0,r5,63	/* If length is odd copy one byte */
 	beq	L(cachelinenotset_align)
 	lbz	r7,0(r4)	/* Read one byte from source */
diff --git a/sysdeps/powerpc/powerpc64/memset.S b/sysdeps/powerpc/powerpc64/memset.S
index 857c023755..2fa98e6e2d 100644
--- a/sysdeps/powerpc/powerpc64/memset.S
+++ b/sysdeps/powerpc/powerpc64/memset.S
@@ -17,10 +17,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include <rtld-global-offsets.h>
 
 	.section	".toc","aw"
-.LC0:
-	.tc __cache_line_size[TC],__cache_line_size
+__GLRO_DEF(dl_cache_line_size)
+
 	.section	".text"
 	.align 2
 
@@ -146,8 +147,10 @@ L(zloopstart):
 /* If the remaining length is less the 32 bytes, don't bother getting
 	 the cache line size.  */
 	beq	L(medium)
-	ld	rCLS,.LC0@toc(r2)
-	lwz	rCLS,0(rCLS)
+	/* Read the cache line size.  */
+	__GLRO (rCLS, dl_cache_line_size,
+		RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET)
+
 /* If the cache line size was not set just goto to L(nondcbz) which is
 	 safe for any cache line size.  */
 	cmpldi	cr1,rCLS,0
diff --git a/sysdeps/powerpc/powerpc64/sysdep.h b/sysdeps/powerpc/powerpc64/sysdep.h
index aefd29a14d..d6616ac905 100644
--- a/sysdeps/powerpc/powerpc64/sysdep.h
+++ b/sysdeps/powerpc/powerpc64/sysdep.h
@@ -342,6 +342,30 @@ LT_LABELSUFFIX(name,_name_end): ; \
 #define	PSEUDO_END_ERRVAL(name) \
   END (name)
 
+#ifdef SHARED
+# if IS_IN (rtld)
+	 /* Inside ld.so we use the local alias to avoid runtime GOT
+	    relocations.  */
+#  define __GLRO_DEF(var)				\
+.LC__ ## var:						\
+	.tc _rtld_local_ro[TC],_rtld_local_ro
+# else
+#  define __GLRO_DEF(var)				\
+.LC__ ## var:						\
+	.tc _rtld_global_ro[TC],_rtld_global_ro
+# endif
+# define __GLRO(rOUT, var, offset)		\
+	ld	rOUT,.LC__ ## var@toc(r2);	\
+	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);	\
+	lwz	rOUT,0(rOUT)
+#endif
+
 #else /* !__ASSEMBLER__ */
 
 #if _CALL_ELF != 2
diff --git a/sysdeps/powerpc/rtld-global-offsets.sym b/sysdeps/powerpc/rtld-global-offsets.sym
index f5ea5a1466..6b348fd522 100644
--- a/sysdeps/powerpc/rtld-global-offsets.sym
+++ b/sysdeps/powerpc/rtld-global-offsets.sym
@@ -6,3 +6,4 @@
 
 RTLD_GLOBAL_RO_DL_HWCAP_OFFSET	rtld_global_ro_offsetof (_dl_hwcap)
 RTLD_GLOBAL_RO_DL_HWCAP2_OFFSET	rtld_global_ro_offsetof (_dl_hwcap2)
+RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET	rtld_global_ro_offsetof (_dl_cache_line_size)
diff --git a/sysdeps/powerpc/tst-cache-ppc-static-dlopen.c b/sysdeps/powerpc/tst-cache-ppc-static-dlopen.c
new file mode 100644
index 0000000000..296d0f4397
--- /dev/null
+++ b/sysdeps/powerpc/tst-cache-ppc-static-dlopen.c
@@ -0,0 +1,54 @@
+/* Test dl_cache_line_size from a dlopen'ed DSO from a static executable.
+   Copyright (C) 2020 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 <dlfcn.h>
+#include <stdio.h>
+#include <errno.h>
+
+int test_cache(int *);
+
+static int
+do_test (void)
+{
+  int ret;
+  void *handle;
+  int (*test_cache) (int *);
+
+  handle = dlopen ("mod-cache-ppc.so", RTLD_LAZY | RTLD_LOCAL);
+  if (handle == NULL)
+    {
+      printf ("dlopen (mod-cache-ppc.so): %s\n", dlerror ());
+      return 1;
+    }
+
+  test_cache = dlsym (handle, "test_cache");
+  if (test_cache == NULL)
+    {
+      printf ("dlsym (test_cache): %s\n", dlerror ());
+      return 1;
+    }
+
+  ret = test_cache(&errno);
+
+  test_cache = NULL;
+  dlclose (handle);
+
+  return ret;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/powerpc/tst-cache-ppc-static.c b/sysdeps/powerpc/tst-cache-ppc-static.c
new file mode 100644
index 0000000000..b0c417e822
--- /dev/null
+++ b/sysdeps/powerpc/tst-cache-ppc-static.c
@@ -0,0 +1,20 @@
+/* Test if an executable can read from _dl_cache_line_size.
+   Copyright (C) 2020 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 "tst-cache-ppc.c"
+#include "mod-cache-ppc.c"
diff --git a/sysdeps/powerpc/tst-cache-ppc.c b/sysdeps/powerpc/tst-cache-ppc.c
new file mode 100644
index 0000000000..86c7117c43
--- /dev/null
+++ b/sysdeps/powerpc/tst-cache-ppc.c
@@ -0,0 +1,29 @@
+/* Test if an executable can read from rtld_global_ro._dl_cache_line_size.
+   Copyright (C) 2020 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 <errno.h>
+
+int test_cache(int *);
+
+static int
+do_test (void)
+{
+  return test_cache(&errno);
+}
+
+#include <support/test-driver.c>