x86: wire up arch_prctl syscall

* linux/i386/syscallent.h [384]: Add arch_prctl entry.
* xlat/archvals.in: Add fallback definitions for constants.
* prctl.c: Stop including <asm/prctl.h>.
(SYS_FUNC(arch_prctl)): Enable for [I386].
* NEWS: Mention this.

NEWS

@@ -18,6 +18,7 @@ Noteworthy changes in release ?.?? (????-??-??)
   * Implemented decoding of netlink message ack flags.
   * Implemented decoding of nlmsgerr netlink attributes.
   * Updated lists of BPF_*, KEY_*, RWF_*, SCM_*, SO_*, and *_MAGIC constants.
+  * Added decoding of arch_prctl syscall on x86.
 
 * Bug fixes
   * Fixed output formatting of blkpg_ioctl_arg, dm_name_list, and iocb

linux/i386/syscallent.h

@@ -410,6 +410,7 @@
 [381] = { 2,	0,		SEN(pkey_alloc),		"pkey_alloc"		},
 [382] = { 1,	0,		SEN(pkey_free),			"pkey_free"		},
 [383] = { 5,	TD|TF|TSTA,	SEN(statx),			"statx"			},
+[384] = { 2,	TP,		SEN(arch_prctl),		"arch_prctl"		},
 
 #define SYS_socket_subcall	400
 #include "subcall.h"

prctl.c

@@ -350,8 +350,7 @@ SYS_FUNC(prctl)
 	return 0;
 }
 
-#if defined X86_64 || defined X32
-# include <asm/prctl.h>
+#if defined X86_64 || defined X32 || defined I386
 # include "xlat/archvals.h"
 
 SYS_FUNC(arch_prctl)
@@ -375,4 +374,4 @@ SYS_FUNC(arch_prctl)
 	tprintf(", %#" PRI_klx, addr);
 	return RVAL_DECODED;
 }
-#endif /* X86_64 || X32 */
+#endif /* X86_64 || X32 || I386 */

xlat/archvals.in

@@ -1,7 +1,7 @@
-ARCH_SET_GS
-ARCH_SET_FS
-ARCH_GET_FS
-ARCH_GET_GS
+ARCH_SET_GS	0x1001
+ARCH_SET_FS	0x1002
+ARCH_GET_FS	0x1003
+ARCH_GET_GS	0x1004
 ARCH_GET_CPUID	0x1011
 ARCH_SET_CPUID	0x1012
 ARCH_MAP_VDSO_X32	0x2001