[S390] 64-bit register support for 31-bit processes

From: Heiko Carstens <heiko.carstens@de.ibm.com>
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/elf.h

@@ -92,6 +92,18 @@
 /* Keep this the last entry.  */
 #define R_390_NUM	61
 
+/* Bits present in AT_HWCAP. */
+#define HWCAP_S390_ESAN3	1
+#define HWCAP_S390_ZARCH	2
+#define HWCAP_S390_STFLE	4
+#define HWCAP_S390_MSA		8
+#define HWCAP_S390_LDISP	16
+#define HWCAP_S390_EIMM		32
+#define HWCAP_S390_DFP		64
+#define HWCAP_S390_HPAGE	128
+#define HWCAP_S390_ETF3EH	256
+#define HWCAP_S390_HIGH_GPRS	512
+
 /*
  * These are used to set parameters in the core dumps.
  */

arch/s390/include/asm/ptrace.h

@@ -311,6 +311,10 @@ typedef struct
 	__u32		orig_gpr2;
 } s390_compat_regs;
 
+typedef struct
+{
+	__u32		gprs_high[NUM_GPRS];
+} s390_compat_regs_high;
 
 #ifdef __KERNEL__
 

arch/s390/include/asm/ucontext.h

@@ -9,6 +9,21 @@
 #ifndef _ASM_S390_UCONTEXT_H
 #define _ASM_S390_UCONTEXT_H
 
+#define UC_EXTENDED	0x00000001
+
+#ifndef __s390x__
+
+struct ucontext_extended {
+	unsigned long	  uc_flags;
+	struct ucontext  *uc_link;
+	stack_t		  uc_stack;
+	_sigregs	  uc_mcontext;
+	unsigned long	  uc_sigmask[2];
+	unsigned long	  uc_gprs_high[16];
+};
+
+#endif
+
 struct ucontext {
 	unsigned long	  uc_flags;
 	struct ucontext  *uc_link;

arch/s390/kernel/compat_signal.c

@@ -39,6 +39,7 @@ typedef struct
 	struct sigcontext32 sc;
 	_sigregs32 sregs;
 	int signo;
+	__u32 gprs_high[NUM_GPRS];
 	__u8 retcode[S390_SYSCALL_SIZE];
 } sigframe32;
 
@@ -48,6 +49,7 @@ typedef struct
 	__u8 retcode[S390_SYSCALL_SIZE];
 	compat_siginfo_t info;
 	struct ucontext32 uc;
+	__u32 gprs_high[NUM_GPRS];
 } rt_sigframe32;
 
 int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
@@ -344,6 +346,30 @@ static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
 	return 0;
 }
 
+static int save_sigregs_gprs_high(struct pt_regs *regs, __u32 __user *uregs)
+{
+	__u32 gprs_high[NUM_GPRS];
+	int i;
+
+	for (i = 0; i < NUM_GPRS; i++)
+		gprs_high[i] = regs->gprs[i] >> 32;
+
+	return __copy_to_user(uregs, &gprs_high, sizeof(gprs_high));
+}
+
+static int restore_sigregs_gprs_high(struct pt_regs *regs, __u32 __user *uregs)
+{
+	__u32 gprs_high[NUM_GPRS];
+	int err, i;
+
+	err = __copy_from_user(&gprs_high, uregs, sizeof(gprs_high));
+	if (err)
+		return err;
+	for (i = 0; i < NUM_GPRS; i++)
+		*(__u32 *)&regs->gprs[i] = gprs_high[i];
+	return 0;
+}
+
 asmlinkage long sys32_sigreturn(void)
 {
 	struct pt_regs *regs = task_pt_regs(current);
@@ -363,6 +389,8 @@ asmlinkage long sys32_sigreturn(void)
 
 	if (restore_sigregs32(regs, &frame->sregs))
 		goto badframe;
+	if (restore_sigregs_gprs_high(regs, frame->gprs_high))
+		goto badframe;
 
 	return regs->gprs[2];
 
@@ -394,6 +422,8 @@ asmlinkage long sys32_rt_sigreturn(void)
 
 	if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
 		goto badframe;
+	if (restore_sigregs_gprs_high(regs, frame->gprs_high))
+		goto badframe;
 
 	err = __get_user(ss_sp, &frame->uc.uc_stack.ss_sp);
 	st.ss_sp = compat_ptr(ss_sp);
@@ -474,6 +504,8 @@ static int setup_frame32(int sig, struct k_sigaction *ka,
 
 	if (save_sigregs32(regs, &frame->sregs))
 		goto give_sigsegv;
+	if (save_sigregs_gprs_high(regs, frame->gprs_high))
+		goto give_sigsegv;
 	if (__put_user((unsigned long) &frame->sregs, &frame->sc.sregs))
 		goto give_sigsegv;
 
@@ -529,13 +561,14 @@ static int setup_rt_frame32(int sig, struct k_sigaction *ka, siginfo_t *info,
 		goto give_sigsegv;
 
 	/* Create the ucontext.  */
-	err |= __put_user(0, &frame->uc.uc_flags);
+	err |= __put_user(UC_EXTENDED, &frame->uc.uc_flags);
 	err |= __put_user(0, &frame->uc.uc_link);
 	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 	err |= __put_user(sas_ss_flags(regs->gprs[15]),
 	                  &frame->uc.uc_stack.ss_flags);
 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 	err |= save_sigregs32(regs, &frame->uc.uc_mcontext);
+	err |= save_sigregs_gprs_high(regs, frame->gprs_high);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)
 		goto give_sigsegv;

arch/s390/kernel/ptrace.c

@@ -57,6 +57,7 @@
 enum s390_regset {
 	REGSET_GENERAL,
 	REGSET_FP,
+	REGSET_GENERAL_EXTENDED,
 };
 
 static void
@@ -879,6 +880,67 @@ static int s390_compat_regs_set(struct task_struct *target,
 	return rc;
 }
 
+static int s390_compat_regs_high_get(struct task_struct *target,
+				     const struct user_regset *regset,
+				     unsigned int pos, unsigned int count,
+				     void *kbuf, void __user *ubuf)
+{
+	compat_ulong_t *gprs_high;
+
+	gprs_high = (compat_ulong_t *)
+		&task_pt_regs(target)->gprs[pos / sizeof(compat_ulong_t)];
+	if (kbuf) {
+		compat_ulong_t *k = kbuf;
+		while (count > 0) {
+			*k++ = *gprs_high;
+			gprs_high += 2;
+			count -= sizeof(*k);
+		}
+	} else {
+		compat_ulong_t __user *u = ubuf;
+		while (count > 0) {
+			if (__put_user(*gprs_high, u++))
+				return -EFAULT;
+			gprs_high += 2;
+			count -= sizeof(*u);
+		}
+	}
+	return 0;
+}
+
+static int s390_compat_regs_high_set(struct task_struct *target,
+				     const struct user_regset *regset,
+				     unsigned int pos, unsigned int count,
+				     const void *kbuf, const void __user *ubuf)
+{
+	compat_ulong_t *gprs_high;
+	int rc = 0;
+
+	gprs_high = (compat_ulong_t *)
+		&task_pt_regs(target)->gprs[pos / sizeof(compat_ulong_t)];
+	if (kbuf) {
+		const compat_ulong_t *k = kbuf;
+		while (count > 0) {
+			*gprs_high = *k++;
+			*gprs_high += 2;
+			count -= sizeof(*k);
+		}
+	} else {
+		const compat_ulong_t  __user *u = ubuf;
+		while (count > 0 && !rc) {
+			unsigned long word;
+			rc = __get_user(word, u++);
+			if (rc)
+				break;
+			*gprs_high = word;
+			*gprs_high += 2;
+			count -= sizeof(*u);
+		}
+	}
+
+	return rc;
+}
+
 static const struct user_regset s390_compat_regsets[] = {
 	[REGSET_GENERAL] = {
 		.core_note_type = NT_PRSTATUS,
@@ -896,6 +958,14 @@ static const struct user_regset s390_compat_regsets[] = {
 		.get = s390_fpregs_get,
 		.set = s390_fpregs_set,
 	},
+	[REGSET_GENERAL_EXTENDED] = {
+		.core_note_type = NT_PRXSTATUS,
+		.n = sizeof(s390_compat_regs_high) / sizeof(compat_long_t),
+		.size = sizeof(compat_long_t),
+		.align = sizeof(compat_long_t),
+		.get = s390_compat_regs_high_get,
+		.set = s390_compat_regs_high_set,
+	},
 };
 
 static const struct user_regset_view user_s390_compat_view = {

arch/s390/kernel/setup.c

@@ -729,7 +729,7 @@ static void __init setup_hwcaps(void)
 
 	if ((facility_list & (1UL << (31 - 22)))
 	    && (facility_list & (1UL << (31 - 30))))
-		elf_hwcap |= 1UL << 8;
+		elf_hwcap |= HWCAP_S390_ETF3EH;
 
 	/*
 	 * Check for additional facilities with store-facility-list-extended.
@@ -748,11 +748,20 @@ static void __init setup_hwcaps(void)
 	    __stfle(&facility_list_extended, 1) > 0) {
 		if ((facility_list_extended & (1ULL << (63 - 42)))
 		    && (facility_list_extended & (1ULL << (63 - 44))))
-			elf_hwcap |= 1UL << 6;
+			elf_hwcap |= HWCAP_S390_DFP;
 	}
 
+	/*
+	 * Huge page support HWCAP_S390_HPAGE is bit 7.
+	 */
 	if (MACHINE_HAS_HPAGE)
-		elf_hwcap |= 1UL << 7;
+		elf_hwcap |= HWCAP_S390_HPAGE;
+
+	/*
+	 * 64-bit register support for 31-bit processes
+	 * HWCAP_S390_HIGH_GPRS is bit 9.
+	 */
+	elf_hwcap |= HWCAP_S390_HIGH_GPRS;
 
 	switch (S390_lowcore.cpu_id.machine) {
 	case 0x9672:

include/linux/elf.h

@@ -361,6 +361,7 @@ typedef struct elf64_shdr {
 #define NT_PPC_VSX	0x102		/* PowerPC VSX registers */
 #define NT_386_TLS	0x200		/* i386 TLS slots (struct user_desc) */
 #define NT_386_IOPERM	0x201		/* x86 io permission bitmap (1=deny) */
+#define NT_PRXSTATUS	0x300		/* s390 upper register halves */
 
 
 /* Note header in a PT_NOTE section */