powerpc: Add HWCAP3/HWCAP4 data to TCB for Power Architecture.

This patch adds a new feature for powerpc.  In order to get faster
access to the HWCAP3/HWCAP4 masks, similar to HWCAP/HWCAP2 (i.e. for
implementing __builtin_cpu_supports() in GCC) without the overhead of
reading them from the auxiliary vector, we now reserve space for them
in the TCB.

This is an ABI change for GLIBC 2.39.

Suggested-by: Peter Bergner <bergner@linux.ibm.com>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
This commit is contained in:
Manjunath Matti 2024-03-19 15:29:48 -05:00 committed by Peter Bergner
parent 3d53d18fc7
commit 3ab9b88e2a
12 changed files with 74 additions and 19 deletions

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@ -235,6 +235,8 @@ _dl_print_diagnostics (char **environ)
_dl_diagnostics_print_labeled_value ("dl_hwcap", GLRO (dl_hwcap));
_dl_diagnostics_print_labeled_value ("dl_hwcap_important", HWCAP_IMPORTANT);
_dl_diagnostics_print_labeled_value ("dl_hwcap2", GLRO (dl_hwcap2));
_dl_diagnostics_print_labeled_value ("dl_hwcap3", GLRO (dl_hwcap3));
_dl_diagnostics_print_labeled_value ("dl_hwcap4", GLRO (dl_hwcap4));
_dl_diagnostics_print_labeled_string
("dl_hwcaps_subdirs", _dl_hwcaps_subdirs);
_dl_diagnostics_print_labeled_value

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@ -158,6 +158,8 @@ const ElfW(Phdr) *_dl_phdr;
size_t _dl_phnum;
uint64_t _dl_hwcap;
uint64_t _dl_hwcap2;
uint64_t _dl_hwcap3;
uint64_t _dl_hwcap4;
enum dso_sort_algorithm _dl_dso_sort_algo;

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@ -1234,6 +1234,10 @@ typedef struct
#define AT_RSEQ_FEATURE_SIZE 27 /* rseq supported feature size. */
#define AT_RSEQ_ALIGN 28 /* rseq allocation alignment. */
/* More machine-dependent hints about processor capabilities. */
#define AT_HWCAP3 29 /* extension of AT_HWCAP. */
#define AT_HWCAP4 30 /* extension of AT_HWCAP. */
#define AT_EXECFN 31 /* Filename of executable. */
/* Pointer to the global system page used for system calls and other

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@ -646,6 +646,8 @@ struct rtld_global_ro
/* Mask for more hardware capabilities that are available on some
platforms. */
EXTERN uint64_t _dl_hwcap2;
EXTERN uint64_t _dl_hwcap3;
EXTERN uint64_t _dl_hwcap4;
EXTERN enum dso_sort_algorithm _dl_dso_sort_algo;

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@ -38,6 +38,10 @@
needed.
*/
/* 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 128
#ifndef PROCINFO_CLASS
# define PROCINFO_CLASS
#endif
@ -61,7 +65,7 @@ PROCINFO_CLASS struct cpu_features _dl_powerpc_cpu_features
#if !defined PROCINFO_DECL && defined SHARED
._dl_powerpc_cap_flags
#else
PROCINFO_CLASS const char _dl_powerpc_cap_flags[64][15]
PROCINFO_CLASS const char _dl_powerpc_cap_flags[_DL_HWCAP_COUNT][15]
#endif
#ifndef PROCINFO_DECL
= {

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@ -22,16 +22,17 @@
#include <ldsodefs.h>
#include <sysdep.h> /* This defines the PPC_FEATURE[2]_* macros. */
/* 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
/* Feature masks are all 32-bits in size. */
#define _DL_HWCAP_SIZE 32
/* Features started at bit 31 and decremented as new features were added. */
#define _DL_HWCAP_LAST 31
/* AT_HWCAP2 feature strings follow the AT_HWCAP feature strings. */
#define _DL_HWCAP2_OFFSET _DL_HWCAP_SIZE
/* AT_HWCAP2 features started at bit 31 and decremented as new features were
added. HWCAP2 feature bits start at bit 0. */
#define _DL_HWCAP2_LAST 31
/* AT_HWCAP3 feature strings follow the AT_HWCAP2 feature strings. */
#define _DL_HWCAP3_OFFSET (_DL_HWCAP2_OFFSET + _DL_HWCAP_SIZE)
/* AT_HWCAP4 feature strings follow the AT_HWCAP3 feature strings. */
#define _DL_HWCAP4_OFFSET (_DL_HWCAP3_OFFSET + _DL_HWCAP_SIZE)
/* These bits influence library search. */
#define HWCAP_IMPORTANT (PPC_FEATURE_HAS_ALTIVEC \
@ -187,21 +188,42 @@ _dl_procinfo (unsigned int type, unsigned long int word)
case AT_HWCAP:
_dl_printf ("AT_HWCAP: ");
for (int i = 0; i <= _DL_HWCAP_LAST; ++i)
for (int i = 0; i < _DL_HWCAP_SIZE; ++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));
/* 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_HWCAP_SIZE; ++i)
if (word & (1 << i))
_dl_printf (" %s", _dl_hwcap_string (_DL_HWCAP2_OFFSET + i));
break;
}
case AT_HWCAP3:
{
_dl_printf ("AT_HWCAP3: ");
/* We have to go through them all because the kernel added the
AT_HWCAP3 features starting with the high bits. */
for (int i = 0; i < _DL_HWCAP_SIZE; ++i)
if (word & (1 << i))
_dl_printf (" %s", _dl_hwcap_string (_DL_HWCAP3_OFFSET + i));
break;
}
case AT_HWCAP4:
{
_dl_printf ("AT_HWCAP4: ");
/* We have to go through them all because the kernel added the
AT_HWCAP4 features starting with the high bits. */
for (int i = 0; i <= _DL_HWCAP_SIZE; ++i)
if (word & (1 << i))
_dl_printf (" %s", _dl_hwcap_string (_DL_HWCAP4_OFFSET + i));
break;
}
case AT_L1I_CACHEGEOMETRY:

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@ -31,7 +31,7 @@ void
__tcb_parse_hwcap_and_convert_at_platform (void)
{
uint64_t h1, h2;
uint64_t h1, h2, h3, h4;
/* Read AT_PLATFORM string from auxv and convert it to a number. */
__tcb.at_platform = _dl_string_platform (GLRO (dl_platform));
@ -39,6 +39,8 @@ __tcb_parse_hwcap_and_convert_at_platform (void)
/* Read HWCAP and HWCAP2 from auxv. */
h1 = GLRO (dl_hwcap);
h2 = GLRO (dl_hwcap2);
h3 = GLRO (dl_hwcap3);
h4 = GLRO (dl_hwcap4);
/* hwcap contains only the latest supported ISA, the code checks which is
and fills the previous supported ones. */
@ -64,13 +66,16 @@ __tcb_parse_hwcap_and_convert_at_platform (void)
else if (h1 & PPC_FEATURE_POWER5)
h1 |= PPC_FEATURE_POWER4;
uint64_t array_hwcaps[] = { h1, h2 };
uint64_t array_hwcaps[] = { h1, h2, h3, h4 };
init_cpu_features (&GLRO(dl_powerpc_cpu_features), array_hwcaps);
/* Consolidate both HWCAP and HWCAP2 into a single doubleword so that
we can read both in a single load later. */
__tcb.hwcap = (h1 << 32) | (h2 & 0xffffffff);
__tcb.hwcap_extn = 0x0;
/* Consolidate both HWCAP3 and HWCAP4 into a single doubleword so that
we can read both in a single load later. */
__tcb.hwcap_extn = (h3 << 32) | (h4 & 0xffffffff);
}
#if IS_IN (rtld)

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@ -47,6 +47,8 @@ void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)
GLRO(dl_platform) = (void *) auxv_values[AT_PLATFORM];
GLRO(dl_hwcap) = auxv_values[AT_HWCAP];
GLRO(dl_hwcap2) = auxv_values[AT_HWCAP2];
GLRO(dl_hwcap3) = auxv_values[AT_HWCAP3];
GLRO(dl_hwcap4) = auxv_values[AT_HWCAP4];
GLRO(dl_clktck) = auxv_values[AT_CLKTCK];
GLRO(dl_fpu_control) = auxv_values[AT_FPUCW];
_dl_random = (void *) auxv_values[AT_RANDOM];

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@ -197,6 +197,8 @@ _dl_show_auxv (void)
[AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
[AT_RANDOM - 2] = { "RANDOM: 0x", hex },
[AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex },
[AT_HWCAP3 - 2] = { "HWCAP3: 0x", hex },
[AT_HWCAP4 - 2] = { "HWCAP4: 0x", hex },
[AT_MINSIGSTKSZ - 2] = { "MINSIGSTKSZ: ", dec },
[AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec },
[AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex },

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@ -94,6 +94,8 @@ init_cpu_features (struct cpu_features *cpu_features, uint64_t hwcaps[])
which are set by __tcb_parse_hwcap_and_convert_at_platform. */
cpu_features->hwcap = hwcaps[0];
cpu_features->hwcap2 = hwcaps[1];
cpu_features->hwcap3 = hwcaps[2];
cpu_features->hwcap4 = hwcaps[3];
/* Default is to use aligned memory access on optimized function unless
tunables is enable, since for this case user can explicit disable
unaligned optimizations. */

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@ -26,6 +26,8 @@ struct cpu_features
bool use_cached_memopt;
unsigned long int hwcap;
unsigned long int hwcap2;
unsigned long int hwcap3;
unsigned long int hwcap4;
};
static const char hwcap_names[] = {

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@ -87,6 +87,12 @@ __libc_start_main_impl (int argc, char **argv,
case AT_HWCAP2:
_dl_hwcap2 = (unsigned long int) av->a_un.a_val;
break;
case AT_HWCAP3:
_dl_hwcap3 = (unsigned long int) av->a_un.a_val;
break;
case AT_HWCAP4:
_dl_hwcap4 = (unsigned long int) av->a_un.a_val;
break;
case AT_PLATFORM:
_dl_platform = (void *) av->a_un.a_val;
break;