[glibc] powerpc: Add space for HWCAP3/HWCAP4 in the TCB for future Power.

[glibc] powerpc: Add space for HWCAP3/HWCAP4 in the TCB for future Power.

[Rajalakshmi Srinivasaraghavan]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=93a739d4a1c34c9dbb96ced4fbeaa18e02000b6a

commit 93a739d4a1c34c9dbb96ced4fbeaa18e02000b6a
Author: Manjunath Matti <mmatti@linux.ibm.com>
Date:   Tue Dec 5 06:38:47 2023 -0600

    powerpc: Add space for HWCAP3/HWCAP4 in the TCB for future Power.
    
    This patch reserves space for HWCAP3/HWCAP4 in the TCB of powerpc.
    These hardware capabilities bits will be used by future Power
    architectures.
    
    Versioned symbol '__parse_hwcap_3_4_and_convert_at_platform' advertises
    the availability of the new HWCAP3/HWCAP4 data in the TCB.
    
    This is an ABI change for GLIBC 2.39.
    
    Suggested-by: Peter Bergner <bergner@linux.ibm.com>
    Reviewed-by: Peter Bergner <bergner@linux.ibm.com>

Diff:
---
 sysdeps/powerpc/Versions                                |  5 +++++
 sysdeps/powerpc/hwcapinfo.c                             |  5 +++++
 sysdeps/powerpc/nptl/tcb-offsets.sym                    |  1 +
 sysdeps/powerpc/nptl/tls.h                              | 13 ++++++++++++-
 sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist    |  1 +
 sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist |  1 +
 sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist |  1 +
 7 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/sysdeps/powerpc/Versions b/sysdeps/powerpc/Versions
index cca8fd2fc5..575f7317bf 100644
--- a/sysdeps/powerpc/Versions
+++ b/sysdeps/powerpc/Versions
@@ -24,4 +24,9 @@ ld {
     # and AT_PLATFORM data should be stored into the TCB.
     __parse_hwcap_and_convert_at_platform;
   }
+  GLIBC_2.39 {
+    # Symbol used to version control when the ABI started to specify that
+    # HWCAP3 and HWCAP4 are stored in the TCB.
+    __parse_hwcap_3_4_and_convert_at_platform;
+  }
 }
diff --git a/sysdeps/powerpc/hwcapinfo.c b/sysdeps/powerpc/hwcapinfo.c
index f2c473c556..a4d5aa1fa6 100644
--- a/sysdeps/powerpc/hwcapinfo.c
+++ b/sysdeps/powerpc/hwcapinfo.c
@@ -70,11 +70,14 @@ __tcb_parse_hwcap_and_convert_at_platform (void)
   /* Consolidate both HWCAP and HWCAP2 into a single doubleword so that
      we can read both in a single load later.  */
   __tcb.hwcap = (h1 << 32) | (h2 & 0xffffffff);
+  __tcb.hwcap_extn = 0x0;
 
 }
 #if IS_IN (rtld)
 versioned_symbol (ld, __tcb_parse_hwcap_and_convert_at_platform, \
 		  __parse_hwcap_and_convert_at_platform, GLIBC_2_23);
+versioned_symbol (ld, __tcb_parse_hwcap_and_convert_at_platform, \
+		  __parse_hwcap_3_4_and_convert_at_platform, GLIBC_2_39);
 #endif
 
 /* Export __parse_hwcap_and_convert_at_platform in libc.a.  This is used by
@@ -83,4 +86,6 @@ versioned_symbol (ld, __tcb_parse_hwcap_and_convert_at_platform, \
 #ifndef SHARED
 weak_alias (__tcb_parse_hwcap_and_convert_at_platform, \
 	    __parse_hwcap_and_convert_at_platform);
+weak_alias (__tcb_parse_hwcap_and_convert_at_platform, \
+	    __parse_hwcap_3_4_and_convert_at_platform);
 #endif
diff --git a/sysdeps/powerpc/nptl/tcb-offsets.sym b/sysdeps/powerpc/nptl/tcb-offsets.sym
index 4c01615ad0..9b29fe8d1a 100644
--- a/sysdeps/powerpc/nptl/tcb-offsets.sym
+++ b/sysdeps/powerpc/nptl/tcb-offsets.sym
@@ -26,3 +26,4 @@ TCB_AT_PLATFORM			(offsetof (tcbhead_t, at_platform) - TLS_TCB_OFFSET - sizeof(t
 PADDING				(offsetof (tcbhead_t, padding) - TLS_TCB_OFFSET - sizeof(tcbhead_t))
 #endif
 TCB_HWCAP			(offsetof (tcbhead_t, hwcap) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
+TCB_HWCAP_EXTN			(offsetof (tcbhead_t, hwcap_extn) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
diff --git a/sysdeps/powerpc/nptl/tls.h b/sysdeps/powerpc/nptl/tls.h
index a668798181..3f8eca57b5 100644
--- a/sysdeps/powerpc/nptl/tls.h
+++ b/sysdeps/powerpc/nptl/tls.h
@@ -64,6 +64,9 @@
    are private.  */
 typedef struct
 {
+  /* Reservation for HWCAP3 and HWCAP4 data.  To be accessed by GCC in
+     __builtin_cpu_supports(), so it is a part of the public ABI.  */
+  uint64_t hwcap_extn;
   /* Reservation for HWCAP data.  To be accessed by GCC in
      __builtin_cpu_supports(), so it is a part of public ABI.  */
   uint64_t hwcap;
@@ -138,6 +141,7 @@ typedef struct
   ({ 									      \
     __thread_register = (void *) (tcbp) + TLS_TCB_OFFSET;		      \
     THREAD_SET_HWCAP (__tcb.hwcap);					      \
+    THREAD_SET_HWCAP_EXTN (__tcb.hwcap_extn);				      \
     THREAD_SET_AT_PLATFORM (__tcb.at_platform);				      \
     true;								      \
   })
@@ -147,6 +151,8 @@ typedef struct
     void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE;	      \
     (((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].hwcap) =	      \
       THREAD_GET_HWCAP ();						      \
+    (((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].hwcap_extn) =	      \
+      THREAD_GET_HWCAP_EXTN ();						      \
     (((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].at_platform) =	      \
       THREAD_GET_AT_PLATFORM ();
 
@@ -189,12 +195,17 @@ typedef struct
 		     + TLS_PRE_TCB_SIZE))[-1].pointer_guard		      \
      = THREAD_GET_POINTER_GUARD())
 
-/* hwcap field in TCB head.  */
+/* hwcap & hwcap_extn fields in TCB head.  */
 # define THREAD_GET_HWCAP() \
     (((tcbhead_t *) ((char *) __thread_register				      \
 		     - TLS_TCB_OFFSET))[-1].hwcap)
+# define THREAD_GET_HWCAP_EXTN() \
+    (((tcbhead_t *) ((char *) __thread_register				      \
+		     - TLS_TCB_OFFSET))[-1].hwcap_extn)
 # define THREAD_SET_HWCAP(value) \
     (THREAD_GET_HWCAP () = (value))
+# define THREAD_SET_HWCAP_EXTN(value) \
+    (THREAD_GET_HWCAP_EXTN () = (value))
 
 /* at_platform field in TCB head.  */
 # define THREAD_GET_AT_PLATFORM() \
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
index 5a68aeb9ee..b1073f0942 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
@@ -8,3 +8,4 @@ GLIBC_2.34 __rtld_version_placeholder F
 GLIBC_2.35 __rseq_flags D 0x4
 GLIBC_2.35 __rseq_offset D 0x4
 GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
index 21f472e674..40942a2cc6 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
@@ -8,3 +8,4 @@ GLIBC_2.34 __rtld_version_placeholder F
 GLIBC_2.35 __rseq_flags D 0x4
 GLIBC_2.35 __rseq_offset D 0x8
 GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
index 9c9c40450d..01f2694a4d 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
@@ -8,3 +8,4 @@ GLIBC_2.34 __rtld_version_placeholder F
 GLIBC_2.35 __rseq_flags D 0x4
 GLIBC_2.35 __rseq_offset D 0x8
 GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F