From 16510517f10757355944ee5c07285ba2a8b61aff Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Mon, 30 Nov 2015 01:46:52 +0000
Subject: [PATCH] cleanup: make get_scno.c files more readable

Make get_scno.c files more self-contained.  While they are still
being included by syscall.c, the latter no longer provides
a function framework for them.

* linux/aarch64/get_scno.c (arch_get_scno): Define.
* linux/alpha/get_scno.c: Likewise.
* linux/arc/get_scno.c: Likewise.
* linux/arm/get_scno.c: Likewise.
* linux/avr32/get_scno.c: Likewise.
* linux/bfin/get_scno.c: Likewise.
* linux/crisv10/get_scno.c: Likewise.
* linux/hppa/get_scno.c: Likewise.
* linux/i386/get_scno.c: Likewise.
* linux/ia64/get_scno.c: Likewise.
* linux/m68k/get_scno.c: Likewise.
* linux/metag/get_scno.c: Likewise.
* linux/microblaze/get_scno.c: Likewise.
* linux/mips/get_scno.c: Likewise.
* linux/nios2/get_scno.c: Likewise.
* linux/or1k/get_scno.c: Likewise.
* linux/powerpc/get_scno.c: Likewise.
* linux/powerpc64/get_scno.c: Likewise.
* linux/s390/get_scno.c: Likewise.
* linux/sh/get_scno.c: Likewise.
* linux/sh64/get_scno.c: Likewise.
* linux/sparc/get_scno.c: Likewise.
* linux/sparc64/get_scno.c: Likewise.
* linux/tile/get_scno.c: Likewise.
* linux/x86_64/get_scno.c: Likewise.
* linux/xtensa/get_scno.c: Likewise.
* syscall.c (arch_get_scno): New declaration.
Include "get_scno.c" in file scope.
(get_scno): Use arch_get_scno.

Requested-by: Denys Vlasenko <dvlasenk@redhat.com>
---
 linux/aarch64/get_scno.c    |  36 ++++---
 linux/alpha/get_scno.c      |  36 ++++---
 linux/arc/get_scno.c        |   8 +-
 linux/arm/get_scno.c        |  80 +++++++++-------
 linux/avr32/get_scno.c      |   8 +-
 linux/bfin/get_scno.c       |   8 +-
 linux/crisv10/get_scno.c    |   8 +-
 linux/hppa/get_scno.c       |   8 +-
 linux/i386/get_scno.c       |   8 +-
 linux/ia64/get_scno.c       |  10 +-
 linux/m68k/get_scno.c       |   8 +-
 linux/metag/get_scno.c      |   8 +-
 linux/microblaze/get_scno.c |   8 +-
 linux/mips/get_scno.c       |  20 ++--
 linux/nios2/get_scno.c      |   8 +-
 linux/or1k/get_scno.c       |   8 +-
 linux/powerpc/get_scno.c    |   8 +-
 linux/powerpc64/get_scno.c  |  26 ++---
 linux/s390/get_scno.c       |   8 +-
 linux/sh/get_scno.c         |  40 +++++---
 linux/sh64/get_scno.c       |  12 ++-
 linux/sparc/get_scno.c      |   8 +-
 linux/sparc64/get_scno.c    |  42 ++++----
 linux/tile/get_scno.c       |  23 +++--
 linux/x86_64/get_scno.c     | 186 +++++++++++++++++++-----------------
 linux/xtensa/get_scno.c     |   8 +-
 syscall.c                   |  19 ++--
 27 files changed, 408 insertions(+), 242 deletions(-)

diff --git a/linux/aarch64/get_scno.c b/linux/aarch64/get_scno.c
index 610b38d7..a712a948 100644
--- a/linux/aarch64/get_scno.c
+++ b/linux/aarch64/get_scno.c
@@ -1,14 +1,24 @@
-switch (aarch64_io.iov_len) {
-	case sizeof(aarch64_regs):
-		/* We are in 64-bit mode */
-		scno = aarch64_regs.regs[8];
-		update_personality(tcp, 1);
-		break;
-	case sizeof(arm_regs):
-		/* We are in 32-bit mode */
-		/* Note: we don't support OABI, unlike 32-bit ARM build */
-		scno = arm_regs.ARM_r7;
-		scno = shuffle_scno(scno);
-		update_personality(tcp, 0);
-		break;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	long scno = 0;
+
+	switch (aarch64_io.iov_len) {
+		case sizeof(aarch64_regs):
+			/* We are in 64-bit mode */
+			scno = aarch64_regs.regs[8];
+			update_personality(tcp, 1);
+			break;
+		case sizeof(arm_regs):
+			/* We are in 32-bit mode */
+			/* Note: we don't support OABI, unlike 32-bit ARM build */
+			scno = arm_regs.ARM_r7;
+			scno = shuffle_scno(scno);
+			update_personality(tcp, 0);
+			break;
+	}
+
+	tcp->scno = scno;
+	return 1;
 }
diff --git a/linux/alpha/get_scno.c b/linux/alpha/get_scno.c
index bf8c3ada..fc099216 100644
--- a/linux/alpha/get_scno.c
+++ b/linux/alpha/get_scno.c
@@ -1,16 +1,26 @@
-if (upeek(tcp->pid, REG_A3, &alpha_a3) < 0)
-	return -1;
-if (upeek(tcp->pid, REG_R0, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	long scno = 0;
 
-/*
- * Do some sanity checks to figure out if it's
- * really a syscall entry
- */
-if (!SCNO_IN_RANGE(scno)) {
-	if (alpha_a3 == 0 || alpha_a3 == -1) {
-		if (debug_flag)
-			error_msg("stray syscall exit: r0 = %ld", scno);
-		return 0;
+	if (upeek(tcp->pid, REG_A3, &alpha_a3) < 0)
+		return -1;
+	if (upeek(tcp->pid, REG_R0, &scno) < 0)
+		return -1;
+
+	/*
+	 * Do some sanity checks to figure out if it's
+	 * really a syscall entry
+	 */
+	if (!SCNO_IN_RANGE(scno)) {
+		if (alpha_a3 == 0 || alpha_a3 == -1) {
+			if (debug_flag)
+				error_msg("stray syscall exit: r0 = %ld", scno);
+			return 0;
+		}
 	}
+
+	tcp->scno = scno;
+	return 1;
 }
diff --git a/linux/arc/get_scno.c b/linux/arc/get_scno.c
index cc45d468..d2046b2d 100644
--- a/linux/arc/get_scno.c
+++ b/linux/arc/get_scno.c
@@ -1 +1,7 @@
-scno = arc_regs.scratch.r8;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = arc_regs.scratch.r8;
+	return 1;
+}
diff --git a/linux/arm/get_scno.c b/linux/arm/get_scno.c
index 6591aa84..d9b6ffc5 100644
--- a/linux/arm/get_scno.c
+++ b/linux/arm/get_scno.c
@@ -1,45 +1,57 @@
-/* Note: we support only 32-bit CPUs, not 26-bit */
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	long scno = 0;
+
+	/* Note: we support only 32-bit CPUs, not 26-bit */
 
 #if !defined(__ARM_EABI__) || ENABLE_ARM_OABI
-if (arm_regs.ARM_cpsr & 0x20) {
-	/* Thumb mode */
-	goto scno_in_r7;
-}
-/* ARM mode */
-/* Check EABI/OABI by examining SVC insn's low 24 bits */
-errno = 0;
-scno = ptrace(PTRACE_PEEKTEXT, tcp->pid, (void *)(arm_regs.ARM_pc - 4), NULL);
-if (errno)
-	return -1;
-/* EABI syscall convention? */
-if ((unsigned long) scno != 0xef000000) {
-	/* No, it's OABI */
-	if ((scno & 0x0ff00000) != 0x0f900000) {
-		error_msg("pid %d unknown syscall trap 0x%08lx",
-			tcp->pid, scno);
+	if (arm_regs.ARM_cpsr & 0x20) {
+		/* Thumb mode */
+		goto scno_in_r7;
+	}
+	/* ARM mode */
+	/* Check EABI/OABI by examining SVC insn's low 24 bits */
+	errno = 0;
+	scno = ptrace(PTRACE_PEEKTEXT, tcp->pid, (void *)(arm_regs.ARM_pc - 4), NULL);
+	if (errno)
 		return -1;
+	/* EABI syscall convention? */
+	if ((unsigned long) scno != 0xef000000) {
+		/* No, it's OABI */
+		if ((scno & 0x0ff00000) != 0x0f900000) {
+			error_msg("pid %d unknown syscall trap 0x%08lx",
+				tcp->pid, scno);
+			return -1;
+		}
+		/* Fixup the syscall number */
+		scno &= 0x000fffff;
+	} else {
+	scno_in_r7:
+		scno = arm_regs.ARM_r7;
 	}
-	/* Fixup the syscall number */
-	scno &= 0x000fffff;
-} else {
-scno_in_r7:
-	scno = arm_regs.ARM_r7;
-}
 #else /* __ARM_EABI__ || !ENABLE_ARM_OABI */
 
-scno = arm_regs.ARM_r7;
+	scno = arm_regs.ARM_r7;
 
 #endif
 
-scno = shuffle_scno(scno);
+	scno = shuffle_scno(scno);
+
+	/*
+	 * Do some sanity checks to figure out
+	 * whether it's really a syscall entry.
+	 */
+	if (arm_regs.ARM_ip && !SCNO_IN_RANGE(scno)) {
+		if (debug_flag)
+			error_msg("pid %d stray syscall exit:"
+				  " ARM_ip = %ld, scno = %ld",
+				  tcp->pid, arm_regs.ARM_ip,
+				  shuffle_scno(scno));
+		return 0;
+	}
 
-/*
- * Do some sanity checks to figure out
- * whether it's really a syscall entry.
- */
-if (arm_regs.ARM_ip && !SCNO_IN_RANGE(scno)) {
-	if (debug_flag)
-		error_msg("pid %d stray syscall exit: ARM_ip = %ld, scno = %ld",
-			  tcp->pid, arm_regs.ARM_ip, shuffle_scno(scno));
-	return 0;
+	tcp->scno = scno;
+	return 1;
 }
diff --git a/linux/avr32/get_scno.c b/linux/avr32/get_scno.c
index 01423299..092dad30 100644
--- a/linux/avr32/get_scno.c
+++ b/linux/avr32/get_scno.c
@@ -1 +1,7 @@
-scno = avr32_regs.r8;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = avr32_regs.r8;
+	return 1;
+}
diff --git a/linux/bfin/get_scno.c b/linux/bfin/get_scno.c
index dfdb0a7c..8c3a7d21 100644
--- a/linux/bfin/get_scno.c
+++ b/linux/bfin/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, PT_ORIG_P0, &scno))
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, PT_ORIG_P0, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/linux/crisv10/get_scno.c b/linux/crisv10/get_scno.c
index 5bbbe8be..14ff3386 100644
--- a/linux/crisv10/get_scno.c
+++ b/linux/crisv10/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, 4*PT_R9, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, 4 * PT_R9, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/linux/hppa/get_scno.c b/linux/hppa/get_scno.c
index 0dc1a465..7da2fc40 100644
--- a/linux/hppa/get_scno.c
+++ b/linux/hppa/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, PT_GR20, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, PT_GR20, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/linux/i386/get_scno.c b/linux/i386/get_scno.c
index fa22fa6c..c2e55510 100644
--- a/linux/i386/get_scno.c
+++ b/linux/i386/get_scno.c
@@ -1 +1,7 @@
-scno = i386_regs.orig_eax;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = i386_regs.orig_eax;
+	return 1;
+}
diff --git a/linux/ia64/get_scno.c b/linux/ia64/get_scno.c
index 86333fd8..0ddc17a9 100644
--- a/linux/ia64/get_scno.c
+++ b/linux/ia64/get_scno.c
@@ -1,5 +1,7 @@
-if (ia64_ia32mode) {
-	scno = ia64_regs.gr[0];
-} else {
-	scno = ia64_regs.gr[15];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = ia64_ia32mode ? ia64_regs.gr[0] : ia64_regs.gr[15];
+	return 1;
 }
diff --git a/linux/m68k/get_scno.c b/linux/m68k/get_scno.c
index 1a6d28e5..716a7616 100644
--- a/linux/m68k/get_scno.c
+++ b/linux/m68k/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, 4*PT_ORIG_D0, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, 4 * PT_ORIG_D0, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/linux/metag/get_scno.c b/linux/metag/get_scno.c
index 45cfa48e..6dc2ab4a 100644
--- a/linux/metag/get_scno.c
+++ b/linux/metag/get_scno.c
@@ -1 +1,7 @@
-scno = metag_regs.dx[0][1];	/* syscall number in D1Re0 (D1.0) */
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = metag_regs.dx[0][1];  /* syscall number in D1Re0 (D1.0) */
+	return 1;
+}
diff --git a/linux/microblaze/get_scno.c b/linux/microblaze/get_scno.c
index cf1d919b..6f98f834 100644
--- a/linux/microblaze/get_scno.c
+++ b/linux/microblaze/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, 0, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, 0, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/linux/mips/get_scno.c b/linux/mips/get_scno.c
index 126cedec..f9b5e7d7 100644
--- a/linux/mips/get_scno.c
+++ b/linux/mips/get_scno.c
@@ -1,9 +1,17 @@
-scno = mips_REG_V0;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = mips_REG_V0;
 
-if (!SCNO_IN_RANGE(scno)) {
-	if (mips_REG_A3 == 0 || mips_REG_A3 == (uint64_t) -1) {
-		if (debug_flag)
-			error_msg("stray syscall exit: v0 = %ld", scno);
-		return 0;
+	if (!SCNO_IN_RANGE(tcp->scno)) {
+		if (mips_REG_A3 == 0 || mips_REG_A3 == (uint64_t) -1) {
+			if (debug_flag)
+				error_msg("stray syscall exit: v0 = %ld",
+					  tcp->scno);
+			return 0;
+		}
 	}
+
+	return 1;
 }
diff --git a/linux/nios2/get_scno.c b/linux/nios2/get_scno.c
index c820bcea..f4db85ee 100644
--- a/linux/nios2/get_scno.c
+++ b/linux/nios2/get_scno.c
@@ -1 +1,7 @@
-scno = nios2_regs.regs[2];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = nios2_regs.regs[2];
+	return 1;
+}
diff --git a/linux/or1k/get_scno.c b/linux/or1k/get_scno.c
index 99fada29..f446c907 100644
--- a/linux/or1k/get_scno.c
+++ b/linux/or1k/get_scno.c
@@ -1 +1,7 @@
-scno = or1k_regs.gpr[11];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = or1k_regs.gpr[11];
+	return 1;
+}
diff --git a/linux/powerpc/get_scno.c b/linux/powerpc/get_scno.c
index a311734b..ef06656f 100644
--- a/linux/powerpc/get_scno.c
+++ b/linux/powerpc/get_scno.c
@@ -1 +1,7 @@
-scno = ppc_regs.gpr[0];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = ppc_regs.gpr[0];
+	return 1;
+}
diff --git a/linux/powerpc64/get_scno.c b/linux/powerpc64/get_scno.c
index 1e670102..8a943e8d 100644
--- a/linux/powerpc64/get_scno.c
+++ b/linux/powerpc64/get_scno.c
@@ -1,11 +1,15 @@
-scno = ppc_regs.gpr[0];
-unsigned int currpers;
-
-/*
- * Check for 64/32 bit mode.
- * Embedded implementations covered by Book E extension of PPC use
- * bit 0 (CM) of 32-bit Machine state register (MSR).
- * Other implementations use bit 0 (SF) of 64-bit MSR.
- */
-currpers = (ppc_regs.msr & 0x8000000080000000) ? 0 : 1;
-update_personality(tcp, currpers);
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = ppc_regs.gpr[0];
+	/*
+	 * Check for 64/32 bit mode.
+	 * Embedded implementations covered by Book E extension of PPC use
+	 * bit 0 (CM) of 32-bit Machine state register (MSR).
+	 * Other implementations use bit 0 (SF) of 64-bit MSR.
+	 */
+	unsigned int currpers = (ppc_regs.msr & 0x8000000080000000) ? 0 : 1;
+	update_personality(tcp, currpers);
+	return 1;
+}
diff --git a/linux/s390/get_scno.c b/linux/s390/get_scno.c
index b9e1c19d..8650e1f1 100644
--- a/linux/s390/get_scno.c
+++ b/linux/s390/get_scno.c
@@ -1 +1,7 @@
-scno = s390_regset.gprs[2];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = s390_regset.gprs[2];
+	return 1;
+}
diff --git a/linux/sh/get_scno.c b/linux/sh/get_scno.c
index b8ce272c..a9bc5d8f 100644
--- a/linux/sh/get_scno.c
+++ b/linux/sh/get_scno.c
@@ -1,17 +1,27 @@
-/*
- * In the new syscall ABI, the system call number is in R3.
- */
-if (upeek(tcp->pid, 4*(REG_REG0+3), &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	long scno = 0;
 
-if (scno < 0) {
-	/* Odd as it may seem, a glibc bug has been known to cause
-	   glibc to issue bogus negative syscall numbers.  So for
-	   our purposes, make strace print what it *should* have been */
-	long correct_scno = (scno & 0xff);
-	if (debug_flag)
-		error_msg("Detected glibc bug: bogus system call"
-			  " number = %ld, correcting to %ld",
-			  scno, correct_scno);
-	scno = correct_scno;
+	/*
+	 * In the new syscall ABI, the system call number is in R3.
+	 */
+	if (upeek(tcp->pid, 4*(REG_REG0+3), &scno) < 0)
+		return -1;
+
+	if (scno < 0) {
+		/* Odd as it may seem, a glibc bug has been known to cause
+		   glibc to issue bogus negative syscall numbers.  So for
+		   our purposes, make strace print what it *should* have been */
+		long correct_scno = (scno & 0xff);
+		if (debug_flag)
+			error_msg("Detected glibc bug: bogus system call"
+				  " number = %ld, correcting to %ld",
+				  scno, correct_scno);
+		scno = correct_scno;
+	}
+
+	tcp->scno = scno;
+	return 1;
 }
diff --git a/linux/sh64/get_scno.c b/linux/sh64/get_scno.c
index 9e7ecd43..50a52232 100644
--- a/linux/sh64/get_scno.c
+++ b/linux/sh64/get_scno.c
@@ -1,3 +1,9 @@
-if (upeek(tcp->pid, REG_SYSCALL, &scno) < 0)
-	return -1;
-scno &= 0xFFFF;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	if (upeek(tcp->pid, REG_SYSCALL, &tcp->scno) < 0)
+		return -1;
+	tcp->scno &= 0xffff;
+	return 1;
+}
diff --git a/linux/sparc/get_scno.c b/linux/sparc/get_scno.c
index b190b6c5..f041259d 100644
--- a/linux/sparc/get_scno.c
+++ b/linux/sparc/get_scno.c
@@ -1 +1,7 @@
-scno = sparc_regs.u_regs[U_REG_G1];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	tcp->scno = sparc_regs.u_regs[U_REG_G1];
+	return 1;
+}
diff --git a/linux/sparc64/get_scno.c b/linux/sparc64/get_scno.c
index b92366e9..32384e69 100644
--- a/linux/sparc64/get_scno.c
+++ b/linux/sparc64/get_scno.c
@@ -1,19 +1,25 @@
-/* Retrieve the syscall trap instruction. */
-unsigned long trap;
-errno = 0;
-trap = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)sparc_regs.tpc, 0);
-if (errno)
-	return -1;
-trap >>= 32;
-switch (trap) {
-case 0x91d02010:
-	/* Linux/SPARC syscall trap. */
-	update_personality(tcp, 0);
-	break;
-case 0x91d0206d:
-	/* Linux/SPARC64 syscall trap. */
-	update_personality(tcp, 1);
-	break;
-}
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	/* Retrieve the syscall trap instruction. */
+	unsigned long trap;
+	errno = 0;
+	trap = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)sparc_regs.tpc, 0);
+	if (errno)
+		return -1;
+	trap >>= 32;
+	switch (trap) {
+	case 0x91d02010:
+		/* Linux/SPARC syscall trap. */
+		update_personality(tcp, 0);
+		break;
+	case 0x91d0206d:
+		/* Linux/SPARC64 syscall trap. */
+		update_personality(tcp, 1);
+		break;
+	}
 
-scno = sparc_regs.u_regs[U_REG_G1];
+	tcp->scno = sparc_regs.u_regs[U_REG_G1];
+	return 1;
+}
diff --git a/linux/tile/get_scno.c b/linux/tile/get_scno.c
index 1ae65c96..e8403d9b 100644
--- a/linux/tile/get_scno.c
+++ b/linux/tile/get_scno.c
@@ -1,17 +1,22 @@
-unsigned int currpers;
-
-scno = tile_regs.regs[10];
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	unsigned int currpers;
 
 #ifdef __tilepro__
-currpers = 1;
+	currpers = 1;
 #else
 # ifndef PT_FLAGS_COMPAT
 #  define PT_FLAGS_COMPAT 0x10000  /* from Linux 3.8 on */
 # endif
-if (tile_regs.flags & PT_FLAGS_COMPAT)
-	currpers = 1;
-else
-	currpers = 0;
+	if (tile_regs.flags & PT_FLAGS_COMPAT)
+		currpers = 1;
+	else
+		currpers = 0;
 #endif
+	update_personality(tcp, currpers);
+	tcp->scno = tile_regs.regs[10];
 
-update_personality(tcp, currpers);
+	return 1;
+}
diff --git a/linux/x86_64/get_scno.c b/linux/x86_64/get_scno.c
index 02ff0a73..8b163de5 100644
--- a/linux/x86_64/get_scno.c
+++ b/linux/x86_64/get_scno.c
@@ -1,104 +1,116 @@
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	long scno = 0;
+	unsigned int currpers;
+
 #ifndef __X32_SYSCALL_BIT
 # define __X32_SYSCALL_BIT	0x40000000
 #endif
 
-unsigned int currpers;
-
 #if 1
-/* GETREGSET of NT_PRSTATUS tells us regset size,
- * which unambiguously detects i386.
- *
- * Linux kernel distinguishes x86-64 and x32 processes
- * solely by looking at __X32_SYSCALL_BIT:
- * arch/x86/include/asm/compat.h::is_x32_task():
- * if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
- *         return true;
- */
-if (x86_io.iov_len == sizeof(i386_regs)) {
-	scno = i386_regs.orig_eax;
-	currpers = 1;
-} else {
-	scno = x86_64_regs.orig_rax;
-	currpers = 0;
-	if (scno & __X32_SYSCALL_BIT) {
-		/*
-		 * Syscall number -1 requires special treatment:
-		 * it might be a side effect of SECCOMP_RET_ERRNO
-		 * filtering that sets orig_rax to -1
-		 * in some versions of linux kernel.
-		 * If that is the case, then
-		 * __X32_SYSCALL_BIT logic does not apply.
-		 */
-		if ((long long) x86_64_regs.orig_rax != -1) {
-			scno -= __X32_SYSCALL_BIT;
-			currpers = 2;
-		} else {
+	/*
+	 * GETREGSET of NT_PRSTATUS tells us regset size,
+	 * which unambiguously detects i386.
+	 *
+	 * Linux kernel distinguishes x86-64 and x32 processes
+	 * solely by looking at __X32_SYSCALL_BIT:
+	 * arch/x86/include/asm/compat.h::is_x32_task():
+	 * if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
+	 *         return true;
+	 */
+	if (x86_io.iov_len == sizeof(i386_regs)) {
+		scno = i386_regs.orig_eax;
+		currpers = 1;
+	} else {
+		scno = x86_64_regs.orig_rax;
+		currpers = 0;
+		if (scno & __X32_SYSCALL_BIT) {
+			/*
+			 * Syscall number -1 requires special treatment:
+			 * it might be a side effect of SECCOMP_RET_ERRNO
+			 * filtering that sets orig_rax to -1
+			 * in some versions of linux kernel.
+			 * If that is the case, then
+			 * __X32_SYSCALL_BIT logic does not apply.
+			 */
+			if ((long long) x86_64_regs.orig_rax != -1) {
+				scno -= __X32_SYSCALL_BIT;
+				currpers = 2;
+			} else {
 # ifdef X32
-			currpers = 2;
+				currpers = 2;
 # endif
+			}
 		}
 	}
-}
 
 #elif 0
-/* cs = 0x33 for long mode (native 64 bit and x32)
- * cs = 0x23 for compatibility mode (32 bit)
- * ds = 0x2b for x32 mode (x86-64 in 32 bit)
- */
-scno = x86_64_regs.orig_rax;
-switch (x86_64_regs.cs) {
-	case 0x23: currpers = 1; break;
-	case 0x33:
-		if (x86_64_regs.ds == 0x2b) {
-			currpers = 2;
-			scno &= ~__X32_SYSCALL_BIT;
-		} else
-			currpers = 0;
-		break;
-	default:
-		error_msg("Unknown value CS=0x%08X while "
-			  "detecting personality of process PID=%d",
-			  (int)x86_64_regs.cs, tcp->pid);
-		currpers = current_personality;
-		break;
-}
+	/*
+	 * cs = 0x33 for long mode (native 64 bit and x32)
+	 * cs = 0x23 for compatibility mode (32 bit)
+	 * ds = 0x2b for x32 mode (x86-64 in 32 bit)
+	 */
+	scno = x86_64_regs.orig_rax;
+	switch (x86_64_regs.cs) {
+		case 0x23: currpers = 1; break;
+		case 0x33:
+			if (x86_64_regs.ds == 0x2b) {
+				currpers = 2;
+				scno &= ~__X32_SYSCALL_BIT;
+			} else
+				currpers = 0;
+			break;
+		default:
+			error_msg("Unknown value CS=0x%08X while "
+				  "detecting personality of process PID=%d",
+				  (int)x86_64_regs.cs, tcp->pid);
+			currpers = current_personality;
+			break;
+	}
 #elif 0
-/* This version analyzes the opcode of a syscall instruction.
- * (int 0x80 on i386 vs. syscall on x86-64)
- * It works, but is too complicated, and strictly speaking, unreliable.
- */
-unsigned long call, rip = x86_64_regs.rip;
-/* sizeof(syscall) == sizeof(int 0x80) == 2 */
-rip -= 2;
-errno = 0;
-call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0);
-if (errno)
-	perror_msg("ptrace_peektext failed");
-switch (call & 0xffff) {
-	/* x86-64: syscall = 0x0f 0x05 */
-	case 0x050f: currpers = 0; break;
-	/* i386: int 0x80 = 0xcd 0x80 */
-	case 0x80cd: currpers = 1; break;
-	default:
-		currpers = current_personality;
-		error_msg("Unknown syscall opcode (0x%04X) while "
-			  "detecting personality of process PID=%d",
-			  (int)call, tcp->pid);
-		break;
-}
+	/*
+	 * This version analyzes the opcode of a syscall instruction.
+	 * (int 0x80 on i386 vs. syscall on x86-64)
+	 * It works, but is too complicated, and strictly speaking, unreliable.
+	 */
+	unsigned long call, rip = x86_64_regs.rip;
+	/* sizeof(syscall) == sizeof(int 0x80) == 2 */
+	rip -= 2;
+	errno = 0;
+	call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0);
+	if (errno)
+		perror_msg("ptrace_peektext failed");
+	switch (call & 0xffff) {
+		/* x86-64: syscall = 0x0f 0x05 */
+		case 0x050f: currpers = 0; break;
+		/* i386: int 0x80 = 0xcd 0x80 */
+		case 0x80cd: currpers = 1; break;
+		default:
+			currpers = current_personality;
+			error_msg("Unknown syscall opcode (0x%04X) while "
+				  "detecting personality of process PID=%d",
+				  (int)call, tcp->pid);
+			break;
+	}
 #endif
 
 #ifdef X32
-/* If we are built for a x32 system, then personality 0 is x32
- * (not x86_64), and stracing of x86_64 apps is not supported.
- * Stracing of i386 apps is still supported.
- */
-if (currpers == 0) {
-	error_msg("syscall_%lu(...) in unsupported "
-		  "64-bit mode of process PID=%d", scno, tcp->pid);
-	return 0;
-}
-currpers &= ~2; /* map 2,1 to 0,1 */
+	/*
+	 * If we are built for a x32 system, then personality 0 is x32
+	 * (not x86_64), and stracing of x86_64 apps is not supported.
+	 * Stracing of i386 apps is still supported.
+	 */
+	if (currpers == 0) {
+		error_msg("syscall_%lu(...) in unsupported "
+			  "64-bit mode of process PID=%d", scno, tcp->pid);
+		return 0;
+	}
+	currpers &= ~2; /* map 2,1 to 0,1 */
 #endif /* X32 */
 
-update_personality(tcp, currpers);
+	update_personality(tcp, currpers);
+	tcp->scno = scno;
+	return 1;
+}
diff --git a/linux/xtensa/get_scno.c b/linux/xtensa/get_scno.c
index 42991630..d230f73b 100644
--- a/linux/xtensa/get_scno.c
+++ b/linux/xtensa/get_scno.c
@@ -1,2 +1,6 @@
-if (upeek(tcp->pid, SYSCALL_NR, &scno) < 0)
-	return -1;
+/* Return codes: 1 - ok, 0 - ignore, other - error. */
+static int
+arch_get_scno(struct tcb *tcp)
+{
+	return upeek(tcp->pid, SYSCALL_NR, &tcp->scno) < 0 ? -1 : 1;
+}
diff --git a/syscall.c b/syscall.c
index 91bd4fa9..3f43a57d 100644
--- a/syscall.c
+++ b/syscall.c
@@ -1302,7 +1302,11 @@ get_regs(pid_t pid)
 #endif
 }
 
-/* Returns:
+static int arch_get_scno(struct tcb *tcp);
+#include "get_scno.c"
+
+/*
+ * Returns:
  * 0: "ignore this ptrace stop", bail out of trace_syscall_entering() silently.
  * 1: ok, continue in trace_syscall_entering().
  * other: error, trace_syscall_entering() should print error indicator
@@ -1314,14 +1318,13 @@ get_scno(struct tcb *tcp)
 	if (get_regs_error)
 		return -1;
 
-	long scno = 0;
-
-#include "get_scno.c"
+	int rc = arch_get_scno(tcp);
+	if (rc != 1)
+		return rc;
 
-	tcp->scno = scno;
 	if (SCNO_IS_VALID(tcp->scno)) {
-		tcp->s_ent = &sysent[scno];
-		tcp->qual_flg = qual_flags[scno];
+		tcp->s_ent = &sysent[tcp->scno];
+		tcp->qual_flg = qual_flags[tcp->scno];
 	} else {
 		static const struct_sysent unknown = {
 			.nargs = MAX_ARGS,
@@ -1332,7 +1335,7 @@ get_scno(struct tcb *tcp)
 		tcp->s_ent = &unknown;
 		tcp->qual_flg = UNDEFINED_SCNO | QUAL_RAW | DEFAULT_QUAL_FLAGS;
 		if (debug_flag)
-			error_msg("pid %d invalid syscall %ld", tcp->pid, scno);
+			error_msg("pid %d invalid syscall %ld", tcp->pid, tcp->scno);
 	}
 	return 1;
 }
-- 
2.40.0