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[PATCH 6/8] tunables: Use glibc.tune.hwcap_mask tunable instead of _dl_hwcap_mask
- From: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- To: libc-alpha at sourceware dot org
- Date: Wed, 10 May 2017 20:17:15 +0530
- Subject: [PATCH 6/8] tunables: Use glibc.tune.hwcap_mask tunable instead of _dl_hwcap_mask
- Authentication-results: sourceware.org; auth=none
- References: <1494427637-14555-1-git-send-email-siddhesh@sourceware.org>
Drop _dl_hwcap_mask when building with tunables. This completes the
transition of hwcap_mask reading from _dl_hwcap_mask to tunables.
* elf/dl-cache.c: Include dl-tunables.h.
(_dl_load_cache_lookup)[HAVE_TUNABLES]: Read
glibc.tune.hwcap_mask.
* elf/dl-hwcaps.c: Include dl-tunables.h.
(_dl_important_hwcaps)[HAVE_TUNABLES]: Read and update
glibc.tune.hwcap_mask.
* sysdeps/sparc/sparc32/dl-machine.h: Likewise.
* elf/dl-support.c (_dl_hwcap2)[HAVE_TUNABLES]: Drop
_dl_hwcap_mask.
* elf/dl-tunables.c (__tunable_set_val): Make a hidden alias.
* elf/dl-tunables.h (__tunable_set_val): Likewise.
* elf/rtld.c (rtld_global_ro)[HAVE_TUNABLES]: Drop
_dl_hwcap_mask.
(process_envvars)[HAVE_TUNABLES]: Likewise.
* sysdeps/generic/ldsodefs.h (rtld_global_ro)[HAVE_TUNABLES]:
Likewise.
---
elf/dl-cache.c | 9 ++++++++-
elf/dl-hwcaps.c | 15 +++++++++++++--
elf/dl-support.c | 2 ++
elf/dl-tunables.c | 1 +
elf/dl-tunables.h | 2 ++
elf/rtld.c | 4 ++++
sysdeps/generic/ldsodefs.h | 2 ++
sysdeps/sparc/sparc32/dl-machine.h | 7 ++++++-
8 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 017c78a..b7ae05c 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -24,6 +24,7 @@
#include <dl-procinfo.h>
#include <stdint.h>
#include <_itoa.h>
+#include <dl-tunables.h>
#ifndef _DL_PLATFORMS_COUNT
# define _DL_PLATFORMS_COUNT 0
@@ -258,8 +259,14 @@ _dl_load_cache_lookup (const char *name)
if (platform != (uint64_t) -1)
platform = 1ULL << platform;
+#if HAVE_TUNABLES
+ uint64_t hwcap_mask = TUNABLE_GET (glibc, tune, hwcap_mask, uint64_t);
+#else
+ uint64_t hwcap_mask = GLRO(dl_hwcap_mask);
+#endif
+
#define _DL_HWCAP_TLS_MASK (1LL << 63)
- uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & GLRO(dl_hwcap_mask))
+ uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & hwcap_mask)
| _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);
/* Only accept hwcap if it's for the right platform. */
diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
index c437397..6a46441a 100644
--- a/elf/dl-hwcaps.c
+++ b/elf/dl-hwcaps.c
@@ -24,6 +24,7 @@
#include <ldsodefs.h>
#include <dl-procinfo.h>
+#include <dl-tunables.h>
#ifdef _DL_FIRST_PLATFORM
# define _DL_FIRST_EXTRA (_DL_FIRST_PLATFORM + _DL_PLATFORMS_COUNT)
@@ -37,8 +38,13 @@ internal_function
_dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
size_t *max_capstrlen)
{
+#if HAVE_TUNABLES
+ uint64_t hwcap_mask = TUNABLE_GET (glibc, tune, hwcap_mask, uint64_t);
+#else
+ uint64_t hwcap_mask = GLRO(dl_hwcap_mask);
+#endif
/* Determine how many important bits are set. */
- uint64_t masked = GLRO(dl_hwcap) & GLRO(dl_hwcap_mask);
+ uint64_t masked = GLRO(dl_hwcap) & hwcap_mask;
size_t cnt = platform != NULL;
size_t n, m;
size_t total;
@@ -125,7 +131,12 @@ _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
LD_HWCAP_MASK environment variable (or default HWCAP_IMPORTANT).
So there is no way to request ignoring an OS-supplied dsocap
string and bit like you can ignore an OS-supplied HWCAP bit. */
- GLRO(dl_hwcap_mask) |= (uint64_t) mask << _DL_FIRST_EXTRA;
+ hwcap_mask |= (uint64_t) mask << _DL_FIRST_EXTRA;
+#if HAVE_TUNABLES
+ TUNABLE_UPDATE_VAL (glibc, tune, hwcap_mask, &hwcap_mask);
+#else
+ GLRO(dl_hwcap_mask) = hwcap_mask;
+#endif
size_t len;
for (const char *p = dsocaps; p < dsocaps + dsocapslen; p += len + 1)
{
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 3c46a7a..c22be85 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -164,6 +164,7 @@ uint64_t _dl_hwcap2 __attribute__ ((nocommon));
/* The value of the FPU control word the kernel will preset in hardware. */
fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
+#if !HAVE_TUNABLES
/* This is not initialized to HWCAP_IMPORTANT, matching the definition
of _dl_important_hwcaps, below, where no hwcap strings are ever
used. This mask is still used to mediate the lookups in the cache
@@ -171,6 +172,7 @@ fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
LD_HWCAP_MASK environment variable here), there is no real point in
setting _dl_hwcap nonzero below, but we do anyway. */
uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
+#endif
/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
* executable but this isn't true for all platforms. */
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index abf10e5..be7733f 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -497,3 +497,4 @@ cb:
if (callback)
callback (&cur->val);
}
+rtld_hidden_def (__tunable_set_val)
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index 7a1124a..79a29a2 100644
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -70,6 +70,8 @@ extern void __tunables_init (char **);
extern void __tunable_set_val (tunable_id_t, void *, tunable_callback_t);
extern void __tunable_update_val (tunable_id_t, void *);
+rtld_hidden_proto (__tunable_set_val)
+
/* Get and return a tunable value. */
# define TUNABLE_GET(__top, __ns, __id, __type) \
({ \
diff --git a/elf/rtld.c b/elf/rtld.c
index 319ef06..3746653 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -159,7 +159,9 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
._dl_debug_fd = STDERR_FILENO,
._dl_use_load_bias = -2,
._dl_correct_cache_id = _DL_CACHE_DEFAULT_ID,
+#if !HAVE_TUNABLES
._dl_hwcap_mask = HWCAP_IMPORTANT,
+#endif
._dl_lazy = 1,
._dl_fpu_control = _FPU_DEFAULT,
._dl_pagesize = EXEC_PAGESIZE,
@@ -2402,6 +2404,7 @@ process_envvars (enum mode *modep)
_dl_show_auxv ();
break;
+#if !HAVE_TUNABLES
case 10:
/* Mask for the important hardware capabilities. */
if (!__libc_enable_secure
@@ -2409,6 +2412,7 @@ process_envvars (enum mode *modep)
GLRO(dl_hwcap_mask) = __strtoul_internal (&envline[11], NULL,
0, 0);
break;
+#endif
case 11:
/* Path where the binary is found. */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index f26a8b2..695ac24 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -515,8 +515,10 @@ struct rtld_global_ro
/* Mask for hardware capabilities that are available. */
EXTERN uint64_t _dl_hwcap;
+#if !HAVE_TUNABLES
/* Mask for important hardware capabilities we honour. */
EXTERN uint64_t _dl_hwcap_mask;
+#endif
#ifdef HAVE_AUX_VECTOR
/* Pointer to the auxv list supplied to the program at startup. */
diff --git a/sysdeps/sparc/sparc32/dl-machine.h b/sysdeps/sparc/sparc32/dl-machine.h
index cf7272f..6923e47 100644
--- a/sysdeps/sparc/sparc32/dl-machine.h
+++ b/sysdeps/sparc/sparc32/dl-machine.h
@@ -39,7 +39,12 @@ elf_machine_matches_host (const Elf32_Ehdr *ehdr)
/* XXX The following is wrong! Dave Miller rejected to implement it
correctly. If this causes problems shoot *him*! */
#ifdef SHARED
- return GLRO(dl_hwcap) & GLRO(dl_hwcap_mask) & HWCAP_SPARC_V9;
+# if HAVE_TUNABLES
+ uint64_t hwcap_mask = TUNABLE_GET (glibc, tune, hwcap_mask);
+# else
+ uint64_t hwcap_mask = GLRO(dl_hwcap_mask);
+# endif
+ return GLRO(dl_hwcap) & hwcap_mask & HWCAP_SPARC_V9;
#else
return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
#endif
--
2.9.3