From: WANG Xuerui <git@xen0n.name>
To: qemu-devel@nongnu.org
Cc: "WANG Xuerui" <git@xen0n.name>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Laurent Vivier" <laurent@vivier.eu>
Subject: [PATCH v4 28/30] linux-user: Add safe syscall handling for loongarch64 hosts
Date: Fri, 24 Sep 2021 00:59:37 +0800 [thread overview]
Message-ID: <20210923165939.729081-29-git@xen0n.name> (raw)
In-Reply-To: <20210923165939.729081-1-git@xen0n.name>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/host/loongarch64/hostdep.h | 34 ++++++++
.../host/loongarch64/safe-syscall.inc.S | 80 +++++++++++++++++++
2 files changed, 114 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..e3d5fa703f
--- /dev/null
+++ b/linux-user/host/loongarch64/hostdep.h
@@ -0,0 +1,34 @@
+/*
+ * 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
+
+#ifndef __ASSEMBLER__
+
+/* These are defined by the safe-syscall.inc.S file */
+extern char safe_syscall_start[];
+extern char safe_syscall_end[];
+
+/* Adjust the signal context to rewind out of safe-syscall if we're in it */
+static inline void rewind_if_in_safe_syscall(void *puc)
+{
+ ucontext_t *uc = puc;
+ unsigned long long *pcreg = &uc->uc_mcontext.__pc;
+
+ if (*pcreg > (uintptr_t)safe_syscall_start
+ && *pcreg < (uintptr_t)safe_syscall_end) {
+ *pcreg = (uintptr_t)safe_syscall_start;
+ }
+}
+
+#endif /* __ASSEMBLER__ */
+
+#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
--
2.33.0
next prev parent reply other threads:[~2021-09-23 17:23 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 16:59 [PATCH v4 00/30] LoongArch64 port of QEMU TCG WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 01/30] elf: Add machine type value for LoongArch WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 02/30] MAINTAINERS: Add tcg/loongarch64 entry with myself as maintainer WANG Xuerui
2021-09-23 17:53 ` Philippe Mathieu-Daudé
2021-09-23 16:59 ` [PATCH v4 03/30] tcg/loongarch64: Add the tcg-target.h file WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 04/30] tcg/loongarch64: Add generated instruction opcodes and encoding helpers WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 05/30] tcg/loongarch64: Add register names, allocation order and input/output sets WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 06/30] tcg/loongarch64: Define the operand constraints WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 07/30] tcg/loongarch64: Implement necessary relocation operations WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 08/30] tcg/loongarch64: Implement the memory barrier op WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 09/30] tcg/loongarch64: Implement tcg_out_mov and tcg_out_movi WANG Xuerui
2021-09-24 14:52 ` Richard Henderson
2021-09-23 16:59 ` [PATCH v4 10/30] tcg/loongarch64: Implement goto_ptr WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 11/30] tcg/loongarch64: Implement sign-/zero-extension ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 12/30] tcg/loongarch64: Implement not/and/or/xor/nor/andc/orc ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 13/30] tcg/loongarch64: Implement deposit/extract ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 14/30] tcg/loongarch64: Implement bswap{16,32,64} ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 15/30] tcg/loongarch64: Implement clz/ctz ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 16/30] tcg/loongarch64: Implement shl/shr/sar/rotl/rotr ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 17/30] tcg/loongarch64: Implement add/sub ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 18/30] tcg/loongarch64: Implement mul/mulsh/muluh/div/divu/rem/remu ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 19/30] tcg/loongarch64: Implement br/brcond ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 20/30] tcg/loongarch64: Implement setcond ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 21/30] tcg/loongarch64: Implement tcg_out_call WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 22/30] tcg/loongarch64: Implement simple load/store ops WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 23/30] tcg/loongarch64: Add softmmu load/store helpers, implement qemu_ld/qemu_st ops WANG Xuerui
2021-09-24 14:56 ` Richard Henderson
2021-09-24 15:19 ` WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 24/30] tcg/loongarch64: Implement tcg_target_qemu_prologue WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 25/30] tcg/loongarch64: Implement exit_tb/goto_tb WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 26/30] tcg/loongarch64: Implement tcg_target_init WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 27/30] tcg/loongarch64: Register the JIT WANG Xuerui
2021-09-23 16:59 ` WANG Xuerui [this message]
2021-09-23 16:59 ` [PATCH v4 29/30] accel/tcg/user-exec: Implement CPU-specific signal handler for loongarch64 hosts WANG Xuerui
2021-09-23 16:59 ` [PATCH v4 30/30] configure, meson.build: Mark support " WANG Xuerui
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