[glibc/arm/gcs] aarch64: add glibc.cpu.aarch64_gcs_policy

[glibc/arm/gcs] aarch64: add glibc.cpu.aarch64_gcs_policy

[Szabolcs Nagy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1e348038b0f013ef9c30e3c4072b9555344391cb

commit 1e348038b0f013ef9c30e3c4072b9555344391cb
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Thu Dec 21 15:14:08 2023 +0000

    aarch64: add glibc.cpu.aarch64_gcs_policy
    
    policy sets how gcs tunable and gcs marking turns into gcs state:
    
    0: state = tunable
    1: state = marking ? tunable : (tunable && dlopen ? err : 0)
    2: state = marking ? tunable : (tunable ? err : 0)
    
    TODO: state lock

Diff:
---
 sysdeps/aarch64/dl-tunables.list               |  5 +++++
 sysdeps/unix/sysv/linux/aarch64/cpu-features.c |  9 +++++++--
 sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c  | 13 +++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/sysdeps/aarch64/dl-tunables.list b/sysdeps/aarch64/dl-tunables.list
index c08be86932..2a07a6216b 100644
--- a/sysdeps/aarch64/dl-tunables.list
+++ b/sysdeps/aarch64/dl-tunables.list
@@ -26,5 +26,10 @@ glibc {
       minval: 0
       default: 0
     }
+    aarch64_gcs_policy {
+      type: UINT_64
+      minval: 0
+      default: 0
+    }
   }
 }
diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
index a8b6a4654a..bab5c32892 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
@@ -130,6 +130,11 @@ init_cpu_features (struct cpu_features *cpu_features)
   cpu_features->mops = GLRO (dl_hwcap2) & HWCAP2_MOPS;
 
   if (GLRO (dl_hwcap2) & HWCAP2_GCS)
-    /* GCS status may be updated later by binary compatibility checks.  */
-    GL (dl_aarch64_gcs) = TUNABLE_GET (glibc, cpu, aarch64_gcs, uint64_t, 0);
+    {
+      /* GCS status may be updated later by binary compatibility checks.  */
+      GL (dl_aarch64_gcs) = TUNABLE_GET (glibc, cpu, aarch64_gcs, uint64_t, 0);
+      /* Fixed GCS policy.  */
+      GLRO (dl_aarch64_gcs_policy) =
+	TUNABLE_GET (glibc, cpu, aarch64_gcs_policy, uint64_t, 0);
+    }
 }
diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
index 7af232de52..a9d5ee9df5 100644
--- a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
+++ b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
@@ -54,6 +54,19 @@ PROCINFO_CLASS struct cpu_features _dl_aarch64_cpu_features
 # else
 ,
 # endif
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_aarch64_gcs_policy
+# else
+PROCINFO_CLASS uint64_t _dl_aarch64_gcs_policy
+# endif
+# ifndef PROCINFO_DECL
+= 0
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
 #endif
 
 /* Number of HWCAP bits set.  */