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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Minios-devel] [UNIKRAFT PATCH 6/6] plat/kvm: System call trap handler (x86_64)
Implements `_ukplat_syscall()` for KVM. The handler is saving the CPU
registers to the stack and calling `ukplat_syscall_handler()` with a
reference to the saved registers. On return, the register values are
loaded back to the CPU.
Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
plat/common/x86/syscall.S | 111 ++++++++++++++++++++++++++++++++++++++
plat/kvm/Config.uk | 3 +-
plat/kvm/Makefile.uk | 3 ++
plat/kvm/x86/setup.c | 4 ++
4 files changed, 119 insertions(+), 2 deletions(-)
create mode 100644 plat/common/x86/syscall.S
diff --git a/plat/common/x86/syscall.S b/plat/common/x86/syscall.S
new file mode 100644
index 00000000..b367a5d7
--- /dev/null
+++ b/plat/common/x86/syscall.S
@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Authors: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
+ *
+ * Copyright (c) 2019, NEC Laboratories Europe GmbH, NEC Corporation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
+ */
+
+#include <uk/arch/lcpu.h>
+
+#define ENTRY(X) .globl X ; X :
+
+ENTRY(_ukplat_syscall)
+ cli
+ /*
+ * Push arguments in the order of 'struct __regs' to the stack.
+ * We are going to handover a refernce to this stack area as
+ * `struct __regs *` argument to the system call handler.
+ */
+ pushq $0 /* exception frame filled with zeros */
+ pushq $0 /* (rip, cs, eflags, rsp, ss) */
+ pushq $0 /* */
+ pushq $0 /* */
+ pushq $0 /* */
+ pushq %rax /* orig_rax */
+ pushq %rdi
+ pushq %rsi
+ pushq %rdx
+ pushq %rcx
+ pushq %rax
+ pushq %r8
+ pushq %r9
+ pushq %r10
+ pushq %r11
+ pushq %rbx
+ pushq %rbp
+ pushq %r12
+ pushq %r13
+ pushq %r14
+ pushq %r15
+ /* padding */
+ subq $(__REGS_PAD_SIZE), %rsp
+ sti
+
+ /*
+ * Handle call
+ * NOTE: Handler function is going to modify saved registers state
+ * NOTE: Stack pointer as "struct __regs *" argument
+ * (calling convention: 1st arg on %rdi)
+ */
+ movq %rsp, %rdi
+ call ukplat_syscall_handler
+
+ cli
+ /* Load the updated state back to registers */
+ addq $(__REGS_PAD_SIZE), %rsp
+ popq %r15
+ popq %r14
+ popq %r13
+ popq %r12
+ popq %rbp
+ popq %rbx
+ popq %r11
+ popq %r10
+ popq %r9
+ popq %r8
+ popq %rax
+ popq %rcx
+ popq %rdx
+ popq %rsi
+ popq %rdi
+ /* orig_rax and exception frame */
+ addq $(6 * 8), %rsp
+ sti
+
+ /*
+ * Return from system call, inspired by HermiTux [1]
+ * NOTE: We can't use sysret because it changes protection mode [1]
+ *
+ * [1] Pierre et al., 2019, A binary-compatible Unikernel,
+ * Proceedings of the 15th ACM SIGPLAN/SIGOPS International
+ * Conference on Virtual Execution Environments (VEE 2019))
+ */
+ jmp *%rcx
diff --git a/plat/kvm/Config.uk b/plat/kvm/Config.uk
index 2bce43ea..432cdd95 100644
--- a/plat/kvm/Config.uk
+++ b/plat/kvm/Config.uk
@@ -1,8 +1,7 @@
menuconfig PLAT_KVM
bool "KVM guest"
default n
- depends on (ARCH_X86_64 || ARCH_ARM_64)
- depends on !HAVE_SYSCALL
+ depends on (ARCH_X86_64 || (ARCH_ARM_64 && !HAVE_SYSCALL))
select LIBUKDEBUG
select LIBUKALLOC
select LIBUKTIMECONV
diff --git a/plat/kvm/Makefile.uk b/plat/kvm/Makefile.uk
index c900d456..63ed9950 100644
--- a/plat/kvm/Makefile.uk
+++ b/plat/kvm/Makefile.uk
@@ -51,6 +51,9 @@ LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) +=
$(UK_PLAT_COMMON_BASE)/x86/thread_start
LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) += $(UK_PLAT_COMMON_BASE)/thread.c|common
LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) += $(UK_PLAT_COMMON_BASE)/sw_ctx.c|common
endif
+ifeq ($(CONFIG_HAVE_SYSCALL),y)
+LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) +=
$(UK_PLAT_COMMON_BASE)/x86/syscall.S|common
+endif
LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) += $(LIBKVMPLAT_BASE)/x86/entry64.S
LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) += $(LIBKVMPLAT_BASE)/x86/traps.c
LIBKVMPLAT_SRCS-$(CONFIG_ARCH_X86_64) +=
$(LIBKVMPLAT_BASE)/x86/cpu_vectors_x86_64.S
diff --git a/plat/kvm/x86/setup.c b/plat/kvm/x86/setup.c
index 44eb7adc..9c7a93a8 100644
--- a/plat/kvm/x86/setup.c
+++ b/plat/kvm/x86/setup.c
@@ -287,6 +287,10 @@ void _libkvmplat_entry(void *arg)
uk_pr_info(" stack top: %p\n",
(void *) _libkvmplat_cfg.bstack.start);
+#ifdef CONFIG_HAVE_SYSCALL
+ _init_syscall();
+#endif /* CONFIG_HAVE_SYSCALL */
+
/*
* Switch away from the bootstrap stack as early as possible.
*/
--
2.20.1
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