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Re: [PATCH] S390: Get cache information via sysconf.
- From: Stefan Liebler <stli at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Fri, 24 Apr 2015 13:16:34 +0200
- Subject: Re: [PATCH] S390: Get cache information via sysconf.
- Authentication-results: sourceware.org; auth=none
- References: <mgr1vn$864$1 at ger dot gmane dot org> <5539F9CA dot 5030804 at linux dot vnet dot ibm dot com>
On 04/24/2015 10:07 AM, Andreas Krebbel wrote:
On 04/17/2015 03:31 PM, Stefan Liebler wrote:
Hi,
this patch adds support to query cache information on s390
via sysconf() function - e.g. with _SC_LEVEL1_ICACHE_SIZE.
The attributes size, linesize and assoc can be queried
for cache level 1 - 4 via "extract cpu attribute" instruction,
which was first available with z10.
Tested on s390/s390x.
Ok to commit?
Bye
Stefan
---
2015-04-17 Stefan Liebler <stli@linux.vnet.ibm.com>
* sysdeps/unix/sysv/linux/s390/sysconf.c: New File.
Thanks! Just some minor nits.
+static long
+__getCacheInfo (int level, int attr, int type)
Urgs camel case ;) Why to start it with __?
+ /* check arguments. */
+ if ((level < 1 || level > CACHE_LEVEL_MAX)
+ || (attr < CACHE_ATTR_LINESIZE || attr > CACHE_ATTR_ASSOC)
+ || (type < CACHE_TYPE_DATA || type > CACHE_TYPE_INSTRUCTION))
+ return 0L;
+
+ /* check if ecag-instruction is available. */
+ /* ecag - extract CPU attribute (only in zarch; arch >= z10; in as 2.24) */
+ if (((GLRO (dl_hwcap) & HWCAP_S390_STFLE) == 0)
+#if !defined __s390x__
+ || ((GLRO (dl_hwcap) & HWCAP_S390_ZARCH) == 0)
+ || ((GLRO (dl_hwcap) & HWCAP_S390_HIGH_GPRS) == 0)
+#endif
Could you please remove the superfluous brackets.
+ /* store facility list and check for z10.
+ (see ifunc-resolver for details) */
...
+ /* check cache topology, if cache is available at this level. */
...
+ /* get cache information for level, attribute and type. */
...
Comments usually start with a capital letter.
Perhaps this qualifies for an entry in the NEWS file?
Bye,
-Andreas-
Ok thanks. Here is the changed patch.
Tested on s390/s390x.
Bye
Stefan
---
2015-04-24 Stefan Liebler <stli@linux.vnet.ibm.com>
* NEWS: Mention sysconf() cache information support for s390.
* sysdeps/unix/sysv/linux/s390/sysconf.c: New File.
diff --git a/NEWS b/NEWS
index ccc4d13..a628b5a 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,9 @@ Version 2.22
18080, 18093, 18100, 18104, 18110, 18111, 18128, 18138, 18185, 18197,
18206, 18210, 18211, 18247, 18287.
+* Cache information can be queried via sysconf() function on s390 e.g. with
+ _SC_LEVEL1_ICACHE_SIZE as argument.
+
* A buffer overflow in gethostbyname_r and related functions performing DNS
requests has been fixed. If the NSS functions were called with a
misaligned buffer, the buffer length change due to pointer alignment was
diff --git a/sysdeps/unix/sysv/linux/s390/sysconf.c b/sysdeps/unix/sysv/linux/s390/sysconf.c
new file mode 100644
index 0000000..7d61c50
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/s390/sysconf.c
@@ -0,0 +1,230 @@
+/* Get system parameters, e.g. cache information. S390/S390x version.
+ Copyright (C) 2015 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <unistd.h>
+#include <dl-procinfo.h>
+
+static long int linux_sysconf (int name);
+
+/* Possible arguments for get_cache_info.
+ The values are reflecting the level/attribute/type indications
+ of ecag-instruction (extract cpu attribue). */
+#define CACHE_LEVEL_MAX 8
+#define CACHE_ATTR_LINESIZE 1
+#define CACHE_ATTR_SIZE 2
+#define CACHE_ATTR_ASSOC 3
+#define CACHE_TYPE_DATA 0
+#define CACHE_TYPE_INSTRUCTION 1
+
+static long
+get_cache_info (int level, int attr, int type)
+{
+ unsigned long int val;
+ unsigned int cmd;
+ unsigned long int arg;
+
+ /* Check arguments. */
+ if (level < 1 || level > CACHE_LEVEL_MAX
+ || attr < CACHE_ATTR_LINESIZE || attr > CACHE_ATTR_ASSOC
+ || type < CACHE_TYPE_DATA || type > CACHE_TYPE_INSTRUCTION)
+ return 0L;
+
+ /* Check if ecag-instruction is available.
+ ecag - extract CPU attribute (only in zarch; arch >= z10; in as 2.24) */
+ if (!(GLRO (dl_hwcap) & HWCAP_S390_STFLE)
+#if !defined __s390x__
+ || !(GLRO (dl_hwcap) & HWCAP_S390_ZARCH)
+ || !(GLRO (dl_hwcap) & HWCAP_S390_HIGH_GPRS)
+#endif /* !__s390x__ */
+ )
+ {
+ /* stfle (or zarch, high-gprs on s390-32) is not available.
+ We are on an old machine. Return 256byte for LINESIZE for L1 d/i-cache,
+ otherwise 0. */
+ if (level == 1 && attr == CACHE_ATTR_LINESIZE)
+ return 256L;
+ else
+ return 0L;
+ }
+
+ /* Store facility list and check for z10.
+ (see ifunc-resolver for details) */
+ register unsigned long reg0 asm("0") = 0;
+#ifdef __s390x__
+ unsigned long stfle_bits;
+# define STFLE_Z10_MASK (1UL << (63 - 34))
+#else
+ unsigned long long stfle_bits;
+# define STFLE_Z10_MASK (1ULL << (63 - 34))
+#endif /* !__s390x__ */
+ asm volatile(".machine push" "\n\t"
+ ".machinemode \"zarch_nohighgprs\"\n\t"
+ ".machine \"z9-109\"" "\n\t"
+ "stfle %0" "\n\t"
+ ".machine pop" "\n"
+ : "=QS" (stfle_bits), "+d" (reg0)
+ : : "cc");
+
+ if (!(stfle_bits & STFLE_Z10_MASK))
+ {
+ /* We are at least on a z9 machine.
+ Return 256byte for LINESIZE for L1 d/i-cache,
+ otherwise 0. */
+ if (level == 1 && attr == CACHE_ATTR_LINESIZE)
+ return 256L;
+ else
+ return 0L;
+ }
+
+ /* Check cache topology, if cache is available at this level. */
+ arg = (CACHE_LEVEL_MAX - level) * 8;
+ asm volatile (".machine push\n\t"
+ ".machine \"z10\"\n\t"
+ ".machinemode \"zarch_nohighgprs\"\n\t"
+ "ecag %0,%%r0,0\n\t" /* returns 64bit unsigned integer. */
+ "srlg %0,%0,0(%1)\n\t" /* right align 8bit cache info field. */
+ ".machine pop"
+ : "=&d" (val)
+ : "a" (arg)
+ );
+ val &= 0xCUL; /* Extract cache scope information from cache topology summary.
+ (bits 4-5 of 8bit-field; 00 means cache does not exist). */
+ if (val == 0)
+ return 0L;
+
+ /* Get cache information for level, attribute and type. */
+ cmd = (attr << 4) | ((level - 1) << 1) | type;
+ asm volatile (".machine push\n\t"
+ ".machine \"z10\"\n\t"
+ ".machinemode \"zarch_nohighgprs\"\n\t"
+ "ecag %0,%%r0,0(%1)\n\t"
+ ".machine pop"
+ : "=d" (val)
+ : "a" (cmd)
+ );
+ return val;
+}
+
+long int
+__sysconf (int name)
+{
+ if (name >= _SC_LEVEL1_ICACHE_SIZE && name <= _SC_LEVEL4_CACHE_LINESIZE)
+ {
+ int level;
+ int attr;
+ int type;
+
+ switch (name)
+ {
+ case _SC_LEVEL1_ICACHE_SIZE:
+ level = 1;
+ attr = CACHE_ATTR_SIZE;
+ type = CACHE_TYPE_INSTRUCTION;
+ break;
+ case _SC_LEVEL1_ICACHE_ASSOC:
+ level = 1;
+ attr = CACHE_ATTR_ASSOC;
+ type = CACHE_TYPE_INSTRUCTION;
+ break;
+ case _SC_LEVEL1_ICACHE_LINESIZE:
+ level = 1;
+ attr = CACHE_ATTR_LINESIZE;
+ type = CACHE_TYPE_INSTRUCTION;
+ break;
+
+ case _SC_LEVEL1_DCACHE_SIZE:
+ level = 1;
+ attr = CACHE_ATTR_SIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL1_DCACHE_ASSOC:
+ level = 1;
+ attr = CACHE_ATTR_ASSOC;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL1_DCACHE_LINESIZE:
+ level = 1;
+ attr = CACHE_ATTR_LINESIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+
+ case _SC_LEVEL2_CACHE_SIZE:
+ level = 2;
+ attr = CACHE_ATTR_SIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL2_CACHE_ASSOC:
+ level = 2;
+ attr = CACHE_ATTR_ASSOC;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL2_CACHE_LINESIZE:
+ level = 2;
+ attr = CACHE_ATTR_LINESIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+
+ case _SC_LEVEL3_CACHE_SIZE:
+ level = 3;
+ attr = CACHE_ATTR_SIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL3_CACHE_ASSOC:
+ level = 3;
+ attr = CACHE_ATTR_ASSOC;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL3_CACHE_LINESIZE:
+ level = 3;
+ attr = CACHE_ATTR_LINESIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+
+ case _SC_LEVEL4_CACHE_SIZE:
+ level = 4;
+ attr = CACHE_ATTR_SIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL4_CACHE_ASSOC:
+ level = 4;
+ attr = CACHE_ATTR_ASSOC;
+ type = CACHE_TYPE_DATA;
+ break;
+ case _SC_LEVEL4_CACHE_LINESIZE:
+ level = 4;
+ attr = CACHE_ATTR_LINESIZE;
+ type = CACHE_TYPE_DATA;
+ break;
+
+ default:
+ level = 0;
+ attr = 0;
+ type = 0;
+ break;
+ }
+
+ return get_cache_info (level, attr, type);
+ }
+
+ return linux_sysconf (name);
+}
+
+/* Now the generic Linux version. */
+#undef __sysconf
+#define __sysconf static linux_sysconf
+#include <sysdeps/unix/sysv/linux/sysconf.c>