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-rw-r--r--Documentation/arm64/elf_hwcaps.txt41
1 files changed, 38 insertions, 3 deletions
diff --git a/Documentation/arm64/elf_hwcaps.txt b/Documentation/arm64/elf_hwcaps.txt
index 13d6691b37be..b73a2519ecf2 100644
--- a/Documentation/arm64/elf_hwcaps.txt
+++ b/Documentation/arm64/elf_hwcaps.txt
@@ -13,9 +13,9 @@ architected discovery mechanism available to userspace code at EL0. The
kernel exposes the presence of these features to userspace through a set
of flags called hwcaps, exposed in the auxilliary vector.
-Userspace software can test for features by acquiring the AT_HWCAP entry
-of the auxilliary vector, and testing whether the relevant flags are
-set, e.g.
+Userspace software can test for features by acquiring the AT_HWCAP or
+AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant
+flags are set, e.g.
bool floating_point_is_present(void)
{
@@ -135,6 +135,10 @@ HWCAP_DCPOP
Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001.
+HWCAP2_DCPODP
+
+ Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010.
+
HWCAP_SHA3
Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001.
@@ -159,6 +163,30 @@ HWCAP_SVE
Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001.
+HWCAP2_SVE2
+
+ Functionality implied by ID_AA64ZFR0_EL1.SVEVer == 0b0001.
+
+HWCAP2_SVEAES
+
+ Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0001.
+
+HWCAP2_SVEPMULL
+
+ Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0010.
+
+HWCAP2_SVEBITPERM
+
+ Functionality implied by ID_AA64ZFR0_EL1.BitPerm == 0b0001.
+
+HWCAP2_SVESHA3
+
+ Functionality implied by ID_AA64ZFR0_EL1.SHA3 == 0b0001.
+
+HWCAP2_SVESM4
+
+ Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001.
+
HWCAP_ASIMDFHM
Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.
@@ -194,3 +222,10 @@ HWCAP_PACG
Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or
ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
Documentation/arm64/pointer-authentication.txt.
+
+
+4. Unused AT_HWCAP bits
+-----------------------
+
+For interoperation with userspace, the kernel guarantees that bits 62
+and 63 of AT_HWCAP will always be returned as 0.