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* [glibc] riscv: Add ifunc helper method to hwprobe.h
@ 2024-03-01 15:17 Palmer Dabbelt
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From: Palmer Dabbelt @ 2024-03-01 15:17 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a2b47f7d4679a01d56827e1aff2a40de173fab23
commit a2b47f7d4679a01d56827e1aff2a40de173fab23
Author: Evan Green <evan@rivosinc.com>
Date: Tue Feb 27 14:56:42 2024 -0800
riscv: Add ifunc helper method to hwprobe.h
Add a little helper method so it's easier to fetch a single value from
the hwprobe function when used within an ifunc selector.
Signed-off-by: Evan Green <evan@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diff:
---
sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h b/sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h
index 34a2e3dbc2..8ecb43bb69 100644
--- a/sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h
+++ b/sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h
@@ -22,6 +22,7 @@
#include <features.h>
#include <stddef.h>
+#include <errno.h>
#ifdef __has_include
# if __has_include (<asm/hwprobe.h>)
# include <asm/hwprobe.h>
@@ -79,6 +80,34 @@ typedef int (*__riscv_hwprobe_t) (struct riscv_hwprobe *__pairs, size_t __pair_c
__fortified_attr_access (__read_write__, 1, 2)
__fortified_attr_access (__read_only__, 4, 3);
+/* Helper function usable from ifunc selectors that probes a single key. */
+static __inline int
+__riscv_hwprobe_one(__riscv_hwprobe_t hwprobe_func,
+ long long int key,
+ unsigned long long int *value)
+{
+ struct riscv_hwprobe pair;
+ int rc;
+
+ /* Earlier versions of glibc pass NULL as the second ifunc parameter. Other C
+ libraries on non-Linux systems may pass +1 as this function pointer to
+ indicate no support. Users copying this function to exotic worlds
+ (non-Linux non-glibc) may want to do additional validity checks here. */
+ if (hwprobe_func == NULL)
+ return ENOSYS;
+
+ pair.key = key;
+ rc = hwprobe_func (&pair, 1, 0, NULL, 0);
+ if (rc != 0)
+ return rc;
+
+ if (pair.key < 0)
+ return ENOENT;
+
+ *value = pair.value;
+ return 0;
+}
+
__END_DECLS
#endif /* sys/hwprobe.h */
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