From: Mark Brown <broonie@kernel.org>
Date: Thu, 7 Jul 2022 10:36:30 +0000 (+0100)
Subject: arm64/hwcap: Document allocation of upper bits of AT_HWCAP
X-Git-Tag: v6.0-rc1~203^2~2^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d3e4a9d30804a78387bfcb383371209417e05c9a;p=thirdparty%2Flinux.git

arm64/hwcap: Document allocation of upper bits of AT_HWCAP

The top two bits of AT_HWCAP are reserved for use by glibc and the rest of
the top 32 bits are being kept unallocated for potential use by glibc.
Document this in the header.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Link: https://lore.kernel.org/r/20220707103632.12745-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index 4bb2cc8ac4466..fd7577cf8e77d 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -19,6 +19,9 @@
 
 /*
  * HWCAP flags - for AT_HWCAP
+ *
+ * Bits 62 and 63 are reserved for use by libc.
+ * Bits 32-61 are unallocated for potential use by libc.
  */
 #define HWCAP_FP		(1 << 0)
 #define HWCAP_ASIMD		(1 << 1)