parisc: Add ARCH_TRACEHOOK and regset support

By adding TRACEHOOK support we now get a clean user interface to access
registers via PTRACE_GETREGS, PTRACE_SETREGS, PTRACE_GETFPREGS and
PTRACE_SETFPREGS.

The user-visible regset struct user_regs_struct and user_fp_struct are
modelled similiar to x86 and can be accessed via PTRACE_GETREGSET.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/Kconfig

@@ -32,6 +32,7 @@ config PARISC
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_ARCH_TRACEHOOK
 	select ARCH_NO_COHERENT_DMA_MMAP
 	select CPU_NO_EFFICIENT_FFS
 

arch/parisc/include/uapi/asm/ptrace.h

@@ -13,6 +13,11 @@
  * N.B. gdb/strace care about the size and offsets within this
  * structure. If you change things, you may break object compatibility
  * for those applications.
+ *
+ * Please do NOT use this structure for future programs, but use
+ * user_regs_struct (see below) instead.
+ *
+ * It can be accessed through PTRACE_PEEKUSR/PTRACE_POKEUSR only.
  */
 
 struct pt_regs {
@@ -33,6 +38,45 @@ struct pt_regs {
 	unsigned long ipsw;	/* CR22 */
 };
 
+/**
+ * struct user_regs_struct - User general purpose registers
+ *
+ * This is the user-visible general purpose register state structure
+ * which is used to define the elf_gregset_t.
+ *
+ * It can be accessed through PTRACE_GETREGSET with NT_PRSTATUS
+ * and through PTRACE_GETREGS.
+ */
+struct user_regs_struct {
+	unsigned long gr[32];	/* PSW is in gr[0] */
+	unsigned long sr[8];
+	unsigned long iaoq[2];
+	unsigned long iasq[2];
+	unsigned long sar;	/* CR11 */
+	unsigned long iir;	/* CR19 */
+	unsigned long isr;	/* CR20 */
+	unsigned long ior;	/* CR21 */
+	unsigned long ipsw;	/* CR22 */
+	unsigned long cr0;
+	unsigned long cr24, cr25, cr26, cr27, cr28, cr29, cr30, cr31;
+	unsigned long cr8, cr9, cr12, cr13, cr10, cr15;
+	unsigned long _pad[80-64];	/* pad to ELF_NGREG (80) */
+};
+
+/**
+ * struct user_fp_struct - User floating point registers
+ *
+ * This is the user-visible floating point register state structure.
+ * It uses the same layout and size as elf_fpregset_t.
+ *
+ * It can be accessed through PTRACE_GETREGSET with NT_PRFPREG
+ * and through PTRACE_GETFPREGS.
+ */
+struct user_fp_struct {
+	__u64 fr[32];
+};
+
+
 /*
  * The numbers chosen here are somewhat arbitrary but absolutely MUST
  * not overlap with any of the number assigned in <linux/ptrace.h>.
@@ -43,5 +87,9 @@ struct pt_regs {
  */
 #define PTRACE_SINGLEBLOCK	12	/* resume execution until next branch */
 
+#define PTRACE_GETREGS		18
+#define PTRACE_SETREGS		19
+#define PTRACE_GETFPREGS	14
+#define PTRACE_SETFPREGS	15
 
 #endif /* _UAPI_PARISC_PTRACE_H */

tools/testing/selftests/seccomp/seccomp_bpf.c

@@ -1234,6 +1234,10 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # define ARCH_REGS	struct user_pt_regs
 # define SYSCALL_NUM	regs[8]
 # define SYSCALL_RET	regs[0]
+#elif defined(__hppa__)
+# define ARCH_REGS	struct user_regs_struct
+# define SYSCALL_NUM	gr[20]
+# define SYSCALL_RET	gr[28]
 #elif defined(__powerpc__)
 # define ARCH_REGS	struct pt_regs
 # define SYSCALL_NUM	gpr[0]
@@ -1303,7 +1307,7 @@ void change_syscall(struct __test_metadata *_metadata,
 	EXPECT_EQ(0, ret);
 
 #if defined(__x86_64__) || defined(__i386__) || defined(__powerpc__) || \
-    defined(__s390__)
+    defined(__s390__) || defined(__hppa__)
 	{
 		regs.SYSCALL_NUM = syscall;
 	}
@@ -1505,6 +1509,8 @@ TEST_F(TRACE_syscall, syscall_dropped)
 #  define __NR_seccomp 383
 # elif defined(__aarch64__)
 #  define __NR_seccomp 277
+# elif defined(__hppa__)
+#  define __NR_seccomp 338
 # elif defined(__powerpc__)
 #  define __NR_seccomp 358
 # elif defined(__s390__)