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Thu, 23 Sep 2021 02:09:45 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=xen0n.name; s=mail; t=1632334185; bh=RK+7W7ncXzWw5siuH9v7BqxTvYSWSwjHyqyPkscUtow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K8vLAYu+ioHIlumFfzx0swDnSMwIpEp2zwUYPWboXnqGlMzbartdZ4zVMq9qHdr/y +AFLPef1u5EU4F280qDQauI4EvkM5IxGk1VuyTC9ttYUBx13JuDk/HCLivceBjA3kR PXwDazeifEIaJ/9SDeD+fvrgrdCrDfMqKx9o5d2A= From: WANG Xuerui To: qemu-devel@nongnu.org Subject: [PATCH v3 28/30] linux-user: Add safe syscall handling for loongarch64 hosts Date: Thu, 23 Sep 2021 02:09:25 +0800 Message-Id: <20210922180927.666273-29-git@xen0n.name> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210922180927.666273-1-git@xen0n.name> References: <20210922180927.666273-1-git@xen0n.name> MIME-Version: 1.0 X-Host-Lookup-Failed: Reverse DNS lookup failed for 115.28.160.31 (failed) Received-SPF: pass client-ip=115.28.160.31; envelope-from=git@xen0n.name; helo=mailbox.box.xen0n.name X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: WANG Xuerui , Peter Maydell , Richard Henderson , =?utf-8?q?Philippe_Mathie?= =?utf-8?q?u-Daud=C3=A9?= , Laurent Vivier Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Signed-off-by: WANG Xuerui Reviewed-by: Richard Henderson --- 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 + * + * Based on safe-syscall.inc.S code for every other architecture, + * originally written by Richard Henderson + * 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