[PATCH] PPC enable Alitvec hardware, part 1

[Steve Munroe <sjmunroe at us dot ibm dot com>]

The attached patch provides base enabling for PowerPC Altivec (AKA VMX) 
and for versioning effected functions. 2.6.0 kernels provide a 
PPC_FEATURE_HAS_ALTIVEC status in the AT_HWCAP. We need to capture this 
status as a static flag (__has_altivec) so functions enabled for altivec 
can run safely on PowerPC hardware without the Altivec feature.

And now for the fun part. I think this requires a new glibc version 
because GLIBC_2.3.3 symbols are already defined for these 
(get/setcontext) functions in shipped distros.
2004-01-09  Steven Munroe  <sjmunroe@us.ibm.com>

	* elf/elf.h: Define PPC_FEATURE_* masks for Aux Vector AT_HWCAP.
	* include/libc-symbols.h [HAVE_ASM_GLOBAL_DOT_NAME]
	(_symbol_version): Use C_SYMBOL_DOT_NAME to create '.'ed symbols.
	(_default_symbol_version): Use C_SYMBOL_DOT_NAME to create '.'ed
	symbols.
	* sysdeps/powerpc/Versions: Add __has_altivec symbol for GLIBC_2.3.4.
	* sysdeps/powerpc/elf/libc-start.c [!SHARED]: Add extern for
	__has_altivec.
	(libc_start_main)[!SHARED]: Initialize __has_altivec from dl_hwcap.
	* sysdeps/powerpc/longjmp.c: New file.
	* sysdeps/powerpc/sysdep.h: Define v# symbols for vector registers.
	* sysdeps/unix/sysv/linux/kernel-features.h
	(__ASSUME_ALTIVEC_SIGCONTEXT): Define for PPC and 2.6.0 kernels.
	* sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c (DL_PLATFORM_INIT):
	Initialize __has_altivec from dl_hwcap.
	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
	[!__ASSUME_ALTIVEC_SIGCONTEXT]: Insure altivec state is defined in
	sigcontext for old kernels.

diff -urN libc23-cvstip-20040102/elf/elf.h libc23/elf/elf.h
--- libc23-cvstip-20040102/elf/elf.h	2003-12-29 12:50:21.000000000 -0600
+++ libc23/elf/elf.h	2004-01-07 14:25:55.000000000 -0600
@@ -1854,6 +1854,17 @@
 #define EF_PPC_RELOCATABLE	0x00010000	/* PowerPC -mrelocatable flag*/
 #define EF_PPC_RELOCATABLE_LIB	0x00008000	/* PowerPC -mrelocatable-lib
 						   flag */
+/* from linux/asm/cputable.h.  */
+#define PPC_FEATURE_32                  0x80000000
+#define PPC_FEATURE_64                  0x40000000
+#define PPC_FEATURE_601_INSTR           0x20000000
+#define PPC_FEATURE_HAS_ALTIVEC         0x10000000
+#define PPC_FEATURE_HAS_FPU             0x08000000
+#define PPC_FEATURE_HAS_MMU             0x04000000
+#define PPC_FEATURE_HAS_4xxMAC          0x02000000
+#define PPC_FEATURE_UNIFIED_CACHE       0x01000000
+
+
 
 /* PowerPC relocations defined by the ABIs */
 #define R_PPC_NONE		0
diff -urN libc23-cvstip-20040102/include/libc-symbols.h libc23/include/libc-symbols.h
--- libc23-cvstip-20040102/include/libc-symbols.h	2003-07-22 14:24:48.000000000 -0500
+++ libc23/include/libc-symbols.h	2004-01-07 14:25:55.000000000 -0600
@@ -420,10 +420,10 @@
 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 #   define _symbol_version(real, name, version) \
      .symver real, name##@##version ASM_LINE_SEP			\
-     .symver .##real, .##name##@##version
+     .symver C_SYMBOL_DOT_NAME(real), C_SYMBOL_DOT_NAME(name##@##version)
 #   define _default_symbol_version(real, name, version) \
      .symver real, name##@##@##version ASM_LINE_SEP			\
-     .symver .##real, .##name##@##@##version
+     .symver C_SYMBOL_DOT_NAME(real), C_SYMBOL_DOT_NAME(name##@##@##version)
 #  else
 #   define _symbol_version(real, name, version) \
      .symver real, name##@##version
diff -urN libc23-cvstip-20040102/sysdeps/powerpc/Versions libc23/sysdeps/powerpc/Versions
--- libc23-cvstip-20040102/sysdeps/powerpc/Versions	2002-09-05 04:54:59.000000000 -0500
+++ libc23/sysdeps/powerpc/Versions	2004-01-10 11:29:00.000000000 -0600
@@ -4,3 +4,9 @@
     __fe_dfl_env; __fe_enabled_env; __fe_nonieee_env; __fe_nomask_env;
   }
 }
+
+ld {
+  GLIBC_2.3.4 { 
+     __has_altivec;
+  }
+}
diff -urN libc23-cvstip-20040102/sysdeps/powerpc/elf/libc-start.c libc23/sysdeps/powerpc/elf/libc-start.c
--- libc23-cvstip-20040102/sysdeps/powerpc/elf/libc-start.c	2003-03-15 17:09:18.000000000 -0600
+++ libc23/sysdeps/powerpc/elf/libc-start.c	2004-01-07 14:25:55.000000000 -0600
@@ -25,6 +25,10 @@
 extern int __cache_line_size;
 weak_extern (__cache_line_size)
 
+#ifndef SHARED
+extern int __has_altivec;
+#endif
+
 /* Scan the Aux Vector for the "Data Cache Block Size" entry.  If found
    verify that the static extern __cache_line_size is defined by checking
    for not NULL.  If it is defined then assign the cache block size
@@ -104,7 +108,9 @@
 
   /* Initialize the __cache_line_size variable from the aux vector.  */
   __aux_init_cache (auxvec);
-
+#ifndef SHARED
+  __has_altivec=((GL(dl_hwcap) & PPC_FEATURE_HAS_ALTIVEC) ? 1:0);
+#endif
   return generic_start_main (stinfo->main, argc, ubp_av, auxvec,
 			     stinfo->init, stinfo->fini, rtld_fini,
 			     stack_on_entry);
diff -urN libc23-cvstip-20040102/sysdeps/powerpc/longjmp.c libc23/sysdeps/powerpc/longjmp.c
--- libc23-cvstip-20040102/sysdeps/powerpc/longjmp.c	Wed Dec 31 18:00:00 1969
+++ libc23/sysdeps/powerpc/longjmp.c	Sat Jan 10 11:29:58 2004
@@ -0,0 +1,56 @@
+/* Copyright (C) 1991,92,94,95,97,98,2000,2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+/*
+  Versioned copy of sysdeps/generic/longjmp.c modified for altivec support.
+ */
+#include  <shlib-compat.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include <signal.h>
+
+#if defined(NOT_IN_libc) || !defined(SHARED)
+/* We don't want this variable both in ld.so & libc.so as
+   we would then have duplicate variable linker confusion.  */
+int vec__has_altivec=0;
+default_symbol_version (vec__has_altivec,__has_altivec,GLIBC_2.3.4);
+#endif
+
+/* Set the signal mask to the one specified in ENV, and jump
+   to the position specified in ENV, causing the setjmp
+   call there to return VAL, or 1 if VAL is 0.  */
+void
+__libc_siglongjmp (sigjmp_buf env, int val)
+{
+  /* Perform any cleanups needed by the frames being unwound.  */
+  _longjmp_unwind (env, val);
+
+  if (env[0].__mask_was_saved)
+    /* Restore the saved signal mask.  */
+    (void) __sigprocmask (SIG_SETMASK, &env[0].__saved_mask,
+			  (sigset_t *) NULL);
+
+  /* Call the machine-dependent function to restore machine state.  */
+  __longjmp (env[0].__jmpbuf, val ?: 1);
+}
+
+strong_alias (__libc_siglongjmp, __libc_longjmp)
+libc_hidden_def (__libc_longjmp)
+weak_alias (__libc_siglongjmp, _longjmp)
+weak_alias (__libc_siglongjmp, longjmp)
+weak_alias (__libc_siglongjmp, siglongjmp)
+
diff -urN libc23-cvstip-20040102/sysdeps/powerpc/sysdep.h libc23/sysdeps/powerpc/sysdep.h
--- libc23-cvstip-20040102/sysdeps/powerpc/sysdep.h	2002-09-20 18:44:55.000000000 -0500
+++ libc23/sysdeps/powerpc/sysdep.h	2004-01-07 14:25:55.000000000 -0600
@@ -100,6 +100,42 @@
 #define cr6	6
 #define cr7	7
 
+/* Vector registers. */
+#define v0	0
+#define v1	1
+#define v2	2
+#define v3	3
+#define v4	4
+#define v5	5
+#define v6	6
+#define v7	7
+#define v8	8
+#define v9	9
+#define v10	10
+#define v11	11
+#define v12	12
+#define v13	13
+#define v14	14
+#define v15	15
+#define v16	16
+#define v17	17
+#define v18	18
+#define v19	19
+#define v20	20
+#define v21	21
+#define v22	22
+#define v23	23
+#define v24	24
+#define v25	25
+#define v26	26
+#define v27	27
+#define v28	28
+#define v29	29
+#define v30	30
+#define v31	31
+
+#define VRSAVE	256
+
 
 #ifdef __ELF__
 
diff -urN libc23-cvstip-20040102/sysdeps/unix/sysv/linux/kernel-features.h libc23/sysdeps/unix/sysv/linux/kernel-features.h
--- libc23-cvstip-20040102/sysdeps/unix/sysv/linux/kernel-features.h	2003-12-11 22:31:39.000000000 -0600
+++ libc23/sysdeps/unix/sysv/linux/kernel-features.h	2004-01-09 19:38:30.000000000 -0600
@@ -247,6 +247,15 @@
 # define __ASSUME_NEW_RT_SIGRETURN_SYSCALL		1
 #endif
 
+/* Starting with 2.6.0 PowerPC adds signal/swapcontext support for Vector 
+   SIMD (AKA Altivec, VMX) instructions and register state.  This changes 
+   the overall size of the sigcontext and adds the swapcontext syscall.  
+   This requires versioning of the setjmp/longjmp and get/make/set/swapcontext
+   functions  */
+#if __LINUX_KERNEL_VERSION >= (132608) && defined __powerpc__
+# define __ASSUME_ALTIVEC_SIGCONTEXT		1
+#endif
+
 /* On x86, the set_thread_area syscall was introduced in 2.5.29, but its
    semantics was changed in 2.5.30, and again after 2.5.31.  */
 #if __LINUX_KERNEL_VERSION >= 132384 && defined __i386__
diff -urN libc23-cvstip-20040102/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c libc23/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c
--- libc23-cvstip-20040102/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c	2003-03-15 18:40:44.000000000 -0600
+++ libc23/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c	2004-01-07 14:25:55.000000000 -0600
@@ -69,4 +69,8 @@
   } while (0)
 #endif
 
+int __has_altivec=0;
+#define DL_PLATFORM_INIT                                                      \
+__has_altivec=((GL(dl_hwcap) & PPC_FEATURE_HAS_ALTIVEC) ? 1:0);
+
 #include <sysdeps/unix/sysv/linux/dl-sysdep.c>
diff -urN libc23-cvstip-20040102/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h libc23/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
--- libc23-cvstip-20040102/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h	2003-12-17 17:11:15.000000000 -0600
+++ libc23/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h	2004-01-10 12:34:56.000000000 -0600
@@ -1,4 +1,4 @@
-/* Copyright (C) 1998, 1999, 2002 Free Software Foundation, Inc.
+/* Copyright (C) 1998, 1999, 2002, 2004 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -29,7 +29,7 @@
 #if __WORDSIZE == 32
 
 /* Number of general registers.  */
-#define NGREG	48
+# define NGREG	48
 
 /* Container for all general registers.  */
 typedef unsigned long gregset_t[NGREG];
@@ -62,8 +62,53 @@
 
 #else
 
-/* For 64-bit, a machine context is exactly a sigcontext.  */
+# ifdef __ASSUME_ALTIVEC_SIGCONTEXT
+/* For 64-bit kernels with Altivec support, a machine context is exactly 
+   a sigcontext.  */
 typedef struct sigcontext mcontext_t;
+# else 
+/* We have old kernel headers.  So we need to allocate space for the 
+   Altivec state here so programs will run correctly when they do run 
+   a new kernel.  */
+   
+#include <asm/types.h>
+
+typedef __vector128 elf_vrreg_t;
+
+struct vmx_sigcontext {
+	unsigned long	_unused[4];
+	int		signal;
+	int		_pad0;
+	unsigned long	handler;
+	unsigned long	oldmask;
+	struct pt_regs	*regs;
+	elf_gregset_t	gp_regs;
+	elf_fpregset_t	fp_regs;
+/*
+ * To maintain compatibility with current implementations the sigcontext is 
+ * extended by appending a pointer (v_regs) to a quadword type (elf_vrreg_t) 
+ * followed by an unstructured (vmx_reserve) field of 69 doublewords.  This 
+ * allows the array of vector registers to be quadword aligned independent of 
+ * the alignment of the containing sigcontext or ucontext. It is the 
+ * responsibility of the code setting the sigcontext to set this pointer to 
+ * either NULL (if this processor does not support the VMX feature) or the 
+ * address of the first quadword within the allocated (vmx_reserve) area.
+ *
+ * The pointer (v_regs) of vector type (elf_vrreg_t) is type compatible with 
+ * an array of 34 quadword entries (elf_vrregset_t).  The entries with 
+ * indexes 0-31 contain the corresponding vector registers.  The entry with 
+ * index 32 contains the vscr as the last word (offset 12) within the 
+ * quadword.  This allows the vscr to be stored as either a quadword (since 
+ * it must be copied via a vector register to/from storage) or as a word.  
+ * The entry with index 33 contains the vrsave as the first word (offset 0) 
+ * within the quadword.
+ */
+	elf_vrreg_t	*v_regs;
+	long		vmx_reserve[69];
+};
+
+typedef struct vmx_sigcontext mcontext_t;
+# endif
 
 #endif