@@ -12,4 +12,7 @@
#ifndef SPARC64_HOSTDEP_H
#define SPARC64_HOSTDEP_H
+/* We have a safe-syscall.inc.S */
+#define HAVE_SAFE_SYSCALL
+
#endif
new file mode 100644
@@ -0,0 +1,89 @@
+/*
+ * safe-syscall.inc.S : host-specific assembly fragment
+ * to handle signals occurring at the same time as system calls.
+ * This is intended to be included by linux-user/safe-syscall.S
+ *
+ * Written by Richard Henderson <richard.henderson@linaro.org>
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+ .text
+ .balign 4
+
+ .register %g2, #scratch
+ .register %g3, #scratch
+
+ .global safe_syscall_base
+ .global safe_syscall_start
+ .global safe_syscall_end
+ .type safe_syscall_base, @function
+ .type safe_syscall_start, @function
+ .type safe_syscall_end, @function
+
+#define STACK_BIAS 2047
+#define PARAM(N) STACK_BIAS + N*8
+
+ /*
+ * This is the entry point for making a system call. The calling
+ * convention here is that of a C varargs function with the
+ * first argument an 'int *' to the signal_pending flag, the
+ * second one the system call number (as a 'long'), and all further
+ * arguments being syscall arguments (also 'long').
+ */
+safe_syscall_base:
+ .cfi_startproc
+ /*
+ * The syscall calling convention isn't the same as the C one:
+ * we enter with o0 == &signal_pending
+ * o1 == syscall number
+ * o2 ... o5, (stack) == syscall arguments
+ * and return the result in x0
+ * and the syscall instruction needs
+ * g1 == syscall number
+ * o0 ... o5 == syscall arguments
+ * and returns the result in o0
+ * Shuffle everything around appropriately.
+ */
+ mov %o0, %g2 /* signal_pending pointer */
+ mov %o1, %g1 /* syscall number */
+ mov %o2, %o0 /* syscall arguments */
+ mov %o3, %o1
+ mov %o4, %o2
+ mov %o5, %o3
+ ldx [%sp + PARAM(6)], %o4
+ ldx [%sp + PARAM(7)], %o5
+
+ /*
+ * This next sequence of code works in conjunction with the
+ * rewind_if_safe_syscall_function(). If a signal is taken
+ * and the interrupted PC is anywhere between 'safe_syscall_start'
+ * and 'safe_syscall_end' then we rewind it to 'safe_syscall_start'.
+ * The code sequence must therefore be able to cope with this, and
+ * the syscall instruction must be the final one in the sequence.
+ */
+safe_syscall_start:
+ /* if signal_pending is non-zero, don't do the call */
+ lduw [%g2], %g3
+ brnz,pn %g3, 2f
+ nop
+ ta 0x6d
+safe_syscall_end:
+ /* code path for having successfully executed the syscall */
+ bcs,pn %xcc, 1f
+ nop
+ ret
+ nop
+
+ /* code path when we didn't execute the syscall */
+2: set TARGET_ERESTARTSYS, %o0
+
+ /* code path setting errno */
+1: mov %o7, %g1
+ call safe_syscall_set_errno_tail
+ mov %g1, %o7
+
+ .cfi_endproc
+ .size safe_syscall_base, .-safe_syscall_base
Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- linux-user/host/sparc64/hostdep.h | 3 + linux-user/host/sparc64/safe-syscall.inc.S | 89 ++++++++++++++++++++++ 2 files changed, 92 insertions(+) create mode 100644 linux-user/host/sparc64/safe-syscall.inc.S