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[PATCH for-7.0 v8 28/31] linux-user: Add safe syscall handling for loong
From: |
WANG Xuerui |
Subject: |
[PATCH for-7.0 v8 28/31] linux-user: Add safe syscall handling for loongarch64 hosts |
Date: |
Thu, 25 Nov 2021 02:32:28 +0800 |
Signed-off-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/host/loongarch64/hostdep.h | 14 ++++
.../host/loongarch64/safe-syscall.inc.S | 80 +++++++++++++++++++
2 files changed, 94 insertions(+)
create mode 100644 linux-user/host/loongarch64/hostdep.h
create mode 100644 linux-user/host/loongarch64/safe-syscall.inc.S
diff --git a/linux-user/host/loongarch64/hostdep.h
b/linux-user/host/loongarch64/hostdep.h
new file mode 100644
index 0000000000..4f692a68b9
--- /dev/null
+++ b/linux-user/host/loongarch64/hostdep.h
@@ -0,0 +1,14 @@
+/*
+ * hostdep.h : things which are dependent on the host architecture
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef LOONGARCH64_HOSTDEP_H
+#define LOONGARCH64_HOSTDEP_H
+
+/* We have a safe-syscall.inc.S */
+#define HAVE_SAFE_SYSCALL
+
+#endif
diff --git a/linux-user/host/loongarch64/safe-syscall.inc.S
b/linux-user/host/loongarch64/safe-syscall.inc.S
new file mode 100644
index 0000000000..bb530248b3
--- /dev/null
+++ b/linux-user/host/loongarch64/safe-syscall.inc.S
@@ -0,0 +1,80 @@
+/*
+ * 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
+ *
+ * Ported to LoongArch by WANG Xuerui <git@xen0n.name>
+ *
+ * Based on safe-syscall.inc.S code for every other architecture,
+ * originally written by Richard Henderson <rth@twiddle.net>
+ * Copyright (C) 2018 Linaro, 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.
+ */
+
+ .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
+
+ /*
+ * 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').
+ * We return a long which is the syscall's return value, which
+ * may be negative-errno on failure. Conversion to the
+ * -1-and-errno-set convention is done by the calling wrapper.
+ */
+safe_syscall_base:
+ .cfi_startproc
+ /*
+ * The syscall calling convention is nearly the same as C:
+ * we enter with a0 == *signal_pending
+ * a1 == syscall number
+ * a2 ... a7 == syscall arguments
+ * and return the result in a0
+ * and the syscall instruction needs
+ * a7 == syscall number
+ * a0 ... a5 == syscall arguments
+ * and returns the result in a0
+ * Shuffle everything around appropriately.
+ */
+ move $t0, $a0 /* signal_pending pointer */
+ move $t1, $a1 /* syscall number */
+ move $a0, $a2 /* syscall arguments */
+ move $a1, $a3
+ move $a2, $a4
+ move $a3, $a5
+ move $a4, $a6
+ move $a5, $a7
+ move $a7, $t1
+
+ /*
+ * 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 */
+ ld.w $t1, $t0, 0
+ bnez $t1, 0f
+ syscall 0
+safe_syscall_end:
+ /* code path for having successfully executed the syscall */
+ jr $ra
+
+0:
+ /* code path when we didn't execute the syscall */
+ li.w $a0, -TARGET_ERESTARTSYS
+ jr $ra
+ .cfi_endproc
+
+ .size safe_syscall_base, .-safe_syscall_base
--
2.34.0
- [PATCH for-7.0 v8 17/31] tcg/loongarch64: Implement add/sub ops, (continued)
- [PATCH for-7.0 v8 17/31] tcg/loongarch64: Implement add/sub ops, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 27/31] tcg/loongarch64: Register the JIT, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 30/31] configure, meson.build: Mark support for loongarch64 hosts, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 29/31] linux-user: Implement CPU-specific signal handler for loongarch64 hosts, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 18/31] tcg/loongarch64: Implement mul/mulsh/muluh/div/divu/rem/remu ops, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 11/31] tcg/loongarch64: Implement sign-/zero-extension ops, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 31/31] tests/docker: Add gentoo-loongarch64-cross image and run cross builds in GitLab, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 20/31] tcg/loongarch64: Implement setcond ops, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 26/31] tcg/loongarch64: Implement tcg_target_init, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 25/31] tcg/loongarch64: Implement exit_tb/goto_tb, WANG Xuerui, 2021/11/24
- [PATCH for-7.0 v8 28/31] linux-user: Add safe syscall handling for loongarch64 hosts,
WANG Xuerui <=
- [PATCH for-7.0 v8 24/31] tcg/loongarch64: Implement tcg_target_qemu_prologue, WANG Xuerui, 2021/11/24