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[PATCH rsa/hwcap2_v4] Implement AT_HWCAP2 version 4
- From: Ryan S Arnold <rsa at linux dot vnet dot ibm dot com>
- To: Roland McGrath <roland at hack dot frob dot com>
- Cc: rsa at us dot ibm dot com, libc-alpha at sourceware dot org
- Date: Thu, 13 Jun 2013 15:09:52 -0500
- Subject: [PATCH rsa/hwcap2_v4] Implement AT_HWCAP2 version 4
- References: <1367611823 dot 9067 dot 294 dot camel at localhost dot localdomain> <20130611221647 dot DCDFF2C07D at topped-with-meat dot com>
On Tue, 2013-06-11 at 15:16 -0700, Roland McGrath wrote:
> The details of the change seem OK except for some formatting trivia below.
>
> My main concern with this is that it doesn't seem to make any sense
> for configurations where auxv entry values are 64 bits already.
> Please explain what it's all supposed to mean in that case.
I think I addressed your concerns with my last email [PATCH
rsa/hwcap2_v3] expect for the following, which I'll correct in the final
version.
> Shouldn't the type of WORD be uint64_t, or at least an unsigned type?
>
> > + switch(type)
I've made some updates to make sysdeps/powerpc/dl-procinfo.h power8
enablement cleaner.
I have one primary concern with my patch set in general. I'm not
entirely sure how the LD_HWCAP_MASK and HWCAP_IMPORTANT masks are
affected by AT_HWCAP2.
Looking at _dl_important_hwcaps:
GLRO(dl_hwcap) |= (uint64_t) mask << _DL_FIRST_EXTRA;
This appears to use the high 32-bits of the hwcap for the pseudo-hwcap
bits (like TLS or anything passed in LD_HWCAP_MASK). On Power I've
allocated all 32-bits of the high-word (since the kernel folks
implemented the PPC_FEATURE2 bits starting on the high-end).
None of the HwCAP MASK/IMPORTANT stuff is very well described, even in
the source.
Ryan S. Arnold
IBM Linux Technology Center
commit 1212598c9429674994da64b3a17375471d809677
Author: Ryan S. Arnold <rsa@linux.vnet.ibm.com>
Date: Thu Jun 13 14:13:39 2013 -0500
Add support for AT_HWCAP2.
[ChangeLog]
2013-06-13 Ryan S. Arnold <rsa@linux.vnet.ibm.com>
* elf/dl-support.c (_dl_aux_init): Add support for AT_HWCAP2.
* elf/dl-sysdep.c (_dl_sysdep_start, _dl_show_auxv): Likewise.
* misc/getauxval.c (__getauxval): Likewise.
* elf/elf.h (AT_HWCAP2): Add a new a_type entry.
* sysdeps/powerpc/dl-procinfo.c (_dl_powerpc_cap_flags): Extend for
for an additional 32 AT_HWCAP2 flags.
* sysdeps/powerpc/dl-procinfo.h (_dl_procinfo): Add support for
displaying AT_HWCAP2 strings. Add TYPE parameter. Make WORD unsigned
rather than signed.
* sysdeps/generic/dl-procinfo.h (_dl_procinfo): Add TYPE parameter to
macro prototype for AT_HWCAP2 support.
* sysdeps/i386/dl-procinfo.h: Likewise.
* sysdeps/s390/dl-procinfo.h: Likewise.
* sysdeps/sparc/dl-procinfo.h (_dl_procinfo): Add TYPE parameter for
future AT_HWCAP2 support. Make WORD unsigned rather than signed.
* sysdeps/unix/sysv/linux/i386/dl-procinfo.h: Likewise.
* sysdeps/unix/sysv/linux/s390/dl-procinfo.h: Likewise.
[ports/ChangeLog.alpha]
2013-06-13 Ryan S. Arnold <rsa@linux.vnet.ibm.com>
* sysdeps/alpha/dl-procinfo.h (_dl_procinfo): Add TYPE parameter for
AT_HWCAP2 support.
[ports/ChangeLog.arm]
2013-06-13 Ryan S. Arnold <rsa@linux.vnet.ibm.com>
* sysdeps/unix/sysv/linux/arm/dl-procinfo.h (_dl_procinfo): Add
TYPE parameter for AT_HWCAP2 support. Make WORD unsigned.
[ports/ChangeLog.mips]
2013-06-13 Ryan S. Arnold <rsa@linux.vnet.ibm.com>
* sysdeps/mips/dl-procinfo.h (_dl_procinfo): Add TYPE parameter for
AT_HWCAP2 support.
diff --git a/elf/dl-support.c b/elf/dl-support.c
index b3ab956..208bc6b 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -194,6 +194,10 @@ _dl_aux_init (ElfW(auxv_t) *av)
uid_t uid = 0;
gid_t gid = 0;
+ /* Don't rely on a specific order of AT_HWCAP and AT_HWCAP2. Collate into a
+ zeroed temp and assign to _dl_hwcap after the auxv has been parsed. */
+ uint64_t hwcap = 0;
+
_dl_auxv = av;
for (; av->a_type != AT_NULL; ++av)
switch (av->a_type)
@@ -212,8 +216,12 @@ _dl_aux_init (ElfW(auxv_t) *av)
GL(dl_phnum) = av->a_un.a_val;
break;
case AT_HWCAP:
- GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
+ hwcap |= (unsigned long int) av->a_un.a_val;
+ break;
+ case AT_HWCAP2:
+ hwcap |= (uint64_t) av->a_un.a_val << 32;
break;
+
#ifdef NEED_DL_SYSINFO
case AT_SYSINFO:
GL(dl_sysinfo) = av->a_un.a_val;
@@ -252,6 +260,9 @@ _dl_aux_init (ElfW(auxv_t) *av)
DL_PLATFORM_AUXV
# endif
}
+
+ GLRO(dl_hwcap) = hwcap;
+
if (seen == 0xf)
{
__libc_enable_secure = uid != 0 || gid != 0;
diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c
index 52de23f..4179cd5 100644
--- a/elf/dl-sysdep.c
+++ b/elf/dl-sysdep.c
@@ -107,6 +107,10 @@ _dl_sysdep_start (void **start_argptr,
uintptr_t new_sysinfo = 0;
#endif
+ /* Don't rely on a specific order of AT_HWCAP and AT_HWCAP2. Collate into a
+ zeroed temp and assign to _dl_hwcap after the auxv has been parsed. */
+ uint64_t hwcap = 0;
+
__libc_stack_end = DL_STACK_END (start_argptr);
DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, INTUSE(_dl_argv), _environ,
GLRO(dl_auxv));
@@ -154,7 +158,10 @@ _dl_sysdep_start (void **start_argptr,
GLRO(dl_platform) = (void *) av->a_un.a_val;
break;
case AT_HWCAP:
- GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
+ hwcap |= (unsigned long int) av->a_un.a_val;
+ break;
+ case AT_HWCAP2:
+ hwcap |= (uint64_t) av->a_un.a_val << 32;
break;
case AT_CLKTCK:
GLRO(dl_clktck) = av->a_un.a_val;
@@ -180,6 +187,8 @@ _dl_sysdep_start (void **start_argptr,
#endif
}
+ GLRO(dl_hwcap) = hwcap;
+
#ifndef HAVE_AUX_SECURE
if (seen != -1)
{
@@ -303,6 +312,7 @@ _dl_show_auxv (void)
[AT_SYSINFO - 2] = { "SYSINFO: 0x", hex },
[AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
[AT_RANDOM - 2] = { "RANDOM: 0x", hex },
+ [AT_HWCAP2 - 2] = { "HWCAP2: ", hex },
};
unsigned int idx = (unsigned int) (av->a_type - 2);
@@ -314,10 +324,11 @@ _dl_show_auxv (void)
assert (AT_NULL == 0);
assert (AT_IGNORE == 1);
- if (av->a_type == AT_HWCAP)
+ if (av->a_type == AT_HWCAP || av->a_type == AT_HWCAP2)
{
- /* This is handled special. */
- if (_dl_procinfo (av->a_un.a_val) == 0)
+ /* HWCAP bits are translated into representative strings, per
+ platform. */
+ if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
continue;
}
diff --git a/elf/elf.h b/elf/elf.h
index 4ad4f39..6c82965 100644
--- a/elf/elf.h
+++ b/elf/elf.h
@@ -993,7 +993,7 @@ typedef struct
/* Some more special a_type values describing the hardware. */
#define AT_PLATFORM 15 /* String identifying platform. */
-#define AT_HWCAP 16 /* Machine dependent hints about
+#define AT_HWCAP 16 /* Machine-dependent hints about
processor capabilities. */
/* This entry gives some information about the FPU initialization
@@ -1015,6 +1015,9 @@ typedef struct
#define AT_RANDOM 25 /* Address of 16 random bytes. */
+#define AT_HWCAP2 26 /* More machine-dependent hints
+ about processor capabilities. */
+
#define AT_EXECFN 31 /* Filename of executable. */
/* Pointer to the global system page used for system calls and other
diff --git a/misc/getauxval.c b/misc/getauxval.c
index 4321e37..0d69922 100644
--- a/misc/getauxval.c
+++ b/misc/getauxval.c
@@ -26,6 +26,8 @@ __getauxval (unsigned long int type)
if (type == AT_HWCAP)
return GLRO(dl_hwcap);
+ else if (type == AT_HWCAP2)
+ return GLRO(dl_hwcap) >> 32;
for (p = GLRO(dl_auxv); p->a_type != AT_NULL; p++)
if (p->a_type == type)
diff --git a/ports/sysdeps/alpha/dl-procinfo.h b/ports/sysdeps/alpha/dl-procinfo.h
index 523d966..0344dbc 100644
--- a/ports/sysdeps/alpha/dl-procinfo.h
+++ b/ports/sysdeps/alpha/dl-procinfo.h
@@ -51,7 +51,7 @@ _dl_string_platform (const char *str)
};
/* We cannot provide a general printing function. */
-#define _dl_procinfo(word) -1
+#define _dl_procinfo(type, word) -1
/* There are no hardware capabilities defined. */
#define _dl_hwcap_string(idx) ""
diff --git a/ports/sysdeps/mips/dl-procinfo.h b/ports/sysdeps/mips/dl-procinfo.h
index 5cc9a44..e96550c 100644
--- a/ports/sysdeps/mips/dl-procinfo.h
+++ b/ports/sysdeps/mips/dl-procinfo.h
@@ -51,7 +51,7 @@ _dl_string_platform (const char *str)
};
/* We cannot provide a general printing function. */
-#define _dl_procinfo(word) -1
+#define _dl_procinfo(type, word) -1
/* There are no hardware capabilities defined. */
#define _dl_hwcap_string(idx) ""
diff --git a/ports/sysdeps/unix/sysv/linux/arm/dl-procinfo.h b/ports/sysdeps/unix/sysv/linux/arm/dl-procinfo.h
index 161e86c..8f71814 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/dl-procinfo.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/dl-procinfo.h
@@ -31,10 +31,14 @@
static inline int
__attribute__ ((unused))
-_dl_procinfo (int word)
+_dl_procinfo (unsigned int type, unsigned int word)
{
int i;
+ /* Unused for now. */
+ if (type == AT_HWCAP2)
+ return 0;
+
_dl_printf ("AT_HWCAP: ");
for (i = 0; i < _DL_HWCAP_COUNT; ++i)
diff --git a/sysdeps/generic/dl-procinfo.h b/sysdeps/generic/dl-procinfo.h
index 90c87d9..a184a59 100644
--- a/sysdeps/generic/dl-procinfo.h
+++ b/sysdeps/generic/dl-procinfo.h
@@ -21,7 +21,7 @@
#define _DL_PROCINFO_H 1
/* We cannot provide a general printing function. */
-#define _dl_procinfo(word) -1
+#define _dl_procinfo(type, word) -1
/* There are no hardware capabilities defined. */
#define _dl_hwcap_string(idx) ""
diff --git a/sysdeps/i386/dl-procinfo.h b/sysdeps/i386/dl-procinfo.h
index 883fa7f..233a325 100644
--- a/sysdeps/i386/dl-procinfo.h
+++ b/sysdeps/i386/dl-procinfo.h
@@ -61,7 +61,7 @@ enum
};
/* We cannot provide a general printing function. */
-#define _dl_procinfo(word) -1
+#define _dl_procinfo(type, word) -1
static inline const char *
__attribute__ ((unused))
diff --git a/sysdeps/powerpc/dl-procinfo.c b/sysdeps/powerpc/dl-procinfo.c
index 0f5c2b3..cb97ed1 100644
--- a/sysdeps/powerpc/dl-procinfo.c
+++ b/sysdeps/powerpc/dl-procinfo.c
@@ -45,7 +45,7 @@
#if !defined PROCINFO_DECL && defined SHARED
._dl_powerpc_cap_flags
#else
-PROCINFO_CLASS const char _dl_powerpc_cap_flags[25][10]
+PROCINFO_CLASS const char _dl_powerpc_cap_flags[57][10]
#endif
#ifndef PROCINFO_DECL
= {
@@ -56,6 +56,14 @@ PROCINFO_CLASS const char _dl_powerpc_cap_flags[25][10]
"notb", "efpdouble", "efpsingle", "spe",
"ucache", "4xxmac", "mmu", "fpu",
"altivec", "ppc601", "ppc64", "ppc32",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
+ "", "", "", "",
}
#endif
#if !defined SHARED || defined PROCINFO_DECL
diff --git a/sysdeps/powerpc/dl-procinfo.h b/sysdeps/powerpc/dl-procinfo.h
index 568fe19..0ffc4f7 100644
--- a/sysdeps/powerpc/dl-procinfo.h
+++ b/sysdeps/powerpc/dl-procinfo.h
@@ -20,11 +20,21 @@
#define _DL_PROCINFO_H 1
#include <ldsodefs.h>
-#include <sysdep.h> /* This defines the PPC_FEATURE_* macros. */
+#include <sysdep.h> /* This defines the PPC_FEATURE[2]_* macros. */
-/* There are 25 bits used, but they are bits 7..31. */
+/* There are 25 bits used in AT_HWCAP, but they are bits 7..31. The feature
+ * definitions started at bit 31 and decremented as new features were added.
+ */
+#define _DL_HWCAP_LAST 31
#define _DL_HWCAP_FIRST 7
-#define _DL_HWCAP_COUNT 32
+
+/* AT_HWCAP2 feature bits similarily started at bit 31 and decremented as new
+ features were added. HWCAP2 feature bits start at bit 0. */
+#define _DL_HWCAP2_LAST 31
+
+/* The total number of available bits (including those prior to
+ _DL_HWCAP_FIRST). Some of these bits might not be used. */
+#define _DL_HWCAP_COUNT 64
/* These bits influence library search. */
#define HWCAP_IMPORTANT (PPC_FEATURE_HAS_ALTIVEC \
@@ -153,15 +163,37 @@ _dl_string_platform (const char *str)
}
#ifdef IS_IN_rtld
+
static inline int
__attribute__ ((unused))
-_dl_procinfo (int word)
+_dl_procinfo (unsigned int type, unsigned int word)
{
- _dl_printf ("AT_HWCAP: ");
-
- for (int i = _DL_HWCAP_FIRST; i < _DL_HWCAP_COUNT; ++i)
- if (word & (1 << i))
- _dl_printf (" %s", _dl_hwcap_string (i));
+ switch(type)
+ {
+ case AT_HWCAP:
+ _dl_printf ("AT_HWCAP: ");
+
+ for (int i = _DL_HWCAP_FIRST; i <= _DL_HWCAP_LAST; ++i)
+ if (word & (1 << i))
+ _dl_printf (" %s", _dl_hwcap_string (i));
+ break;
+ case AT_HWCAP2:
+ {
+ unsigned int offset = _DL_HWCAP_LAST + 1;
+
+ _dl_printf ("AT_HWCAP2: ");
+
+ /* We have to go through them all because the kernel added the
+ AT_HWCAP2 features starting with the high bits. */
+ for (int i = 0; i <= _DL_HWCAP2_LAST; ++i)
+ if (word & (1 << i))
+ _dl_printf (" %s", _dl_hwcap_string (offset + i));
+ break;
+ }
+ default:
+ /* This should not happen. */
+ return -1;
+ }
_dl_printf ("\n");
diff --git a/sysdeps/s390/dl-procinfo.h b/sysdeps/s390/dl-procinfo.h
index 717f6f9..45e27f1 100644
--- a/sysdeps/s390/dl-procinfo.h
+++ b/sysdeps/s390/dl-procinfo.h
@@ -56,7 +56,7 @@ enum
| HWCAP_S390_EIMM | HWCAP_S390_DFP)
/* We cannot provide a general printing function. */
-#define _dl_procinfo(word) -1
+#define _dl_procinfo(type, word) -1
static inline const char *
__attribute__ ((unused))
diff --git a/sysdeps/sparc/dl-procinfo.h b/sysdeps/sparc/dl-procinfo.h
index a18b099..1594ee0 100644
+++ b/sysdeps/sparc/dl-procinfo.h
@@ -27,10 +27,14 @@
static inline int
__attribute__ ((unused))
-_dl_procinfo (int word)
+_dl_procinfo (unsigned int type, unsigned int word)
{
int i;
+ /* Unused for now. */
+ if (type == AT_HWCAP2)
+ return 0;
+
_dl_printf ("AT_HWCAP: ");
for (i = 0; i < _DL_HWCAP_COUNT; ++i)
diff --git a/sysdeps/unix/sysv/linux/i386/dl-procinfo.h b/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
index a82f8f5..225a5eb 100644
--- a/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
+++ b/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
@@ -24,12 +24,16 @@
#undef _dl_procinfo
static inline int
__attribute__ ((unused))
-_dl_procinfo (int word)
+_dl_procinfo (unsigned int type, unsigned int word)
{
/* This table should match the information from arch/i386/kernel/setup.c
in the kernel sources. */
int i;
+ /* Unused for now. */
+ if (type == AT_HWCAP2)
+ return 0;
+
_dl_printf ("AT_HWCAP: ");
for (i = 0; i < _DL_HWCAP_COUNT; ++i)
diff --git a/sysdeps/unix/sysv/linux/s390/dl-procinfo.h b/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
index 5ca4b76..eb60fc2 100644
--- a/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
+++ b/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
@@ -24,12 +24,16 @@
#undef _dl_procinfo
static inline int
__attribute__ ((unused))
-_dl_procinfo (int word)
+_dl_procinfo (unsigned int type, unsigned int word)
{
/* This table should match the information from arch/s390/kernel/setup.c
in the kernel sources. */
int i;
+ /* Unused for now. */
+ if (type == AT_HWCAP2)
+ return 0;
+
_dl_printf ("AT_HWCAP: ");
for (i = 0; i < _DL_HWCAP_COUNT; ++i)