Since ptrace facility isn't used under !MMU of UML, there is different
code path to invoke processes/threads; there are no external process
used, and need to properly configure some of registers (fs segment
register for TLS, etc) on every context switch, etc.
Signals aren't delivered in non-ptrace syscall entry/leave so, we also
need to handle pending signal by ourselves.
Signed-off-by: Hajime Tazaki <thehaj...@gmail.com>
Signed-off-by: Ricardo Koller <ricar...@google.com>
---
arch/um/os-Linux/process.c | 6 +++++
arch/x86/um/Makefile | 3 ++-
arch/x86/um/nommu/Makefile | 2 +-
arch/x86/um/nommu/entry_64.S | 22 +++++++++++++++++
arch/x86/um/nommu/syscalls_64.c | 44 +++++++++++++++++++++++++++++++++
5 files changed, 75 insertions(+), 2 deletions(-)
create mode 100644 arch/x86/um/nommu/syscalls_64.c
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index e2dc00fc84c0..49aa8e92205e 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -28,6 +28,9 @@ int unscheduled_userspace_iterations;
void os_alarm_process(int pid)
{
+ if (pid <= 0)
+ return;
+
kill(pid, SIGALRM);
}
@@ -45,6 +48,9 @@ void os_kill_process(int pid, int reap_child)
void os_kill_ptraced_process(int pid, int reap_child)
{
+ if (pid <= 0)
+ return;
+
kill(pid, SIGKILL);
ptrace(PTRACE_KILL, pid);
ptrace(PTRACE_CONT, pid);
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index 227af2a987e2..53c9ebb3c41c 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -27,7 +27,8 @@ subarch-y += ../kernel/sys_ia32.o
else
-obj-y += syscalls_64.o vdso/
+obj-y += vdso/
+obj-$(CONFIG_MMU) += syscalls_64.o
subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \
../lib/memmove_64.o ../lib/memset_64.o
diff --git a/arch/x86/um/nommu/Makefile b/arch/x86/um/nommu/Makefile
index ebe47d4836f4..4018d9e0aba0 100644
--- a/arch/x86/um/nommu/Makefile
+++ b/arch/x86/um/nommu/Makefile
@@ -5,4 +5,4 @@ else
BITS := 64
endif
-obj-y = do_syscall_$(BITS).o entry_$(BITS).o os-Linux/
+obj-y = do_syscall_$(BITS).o entry_$(BITS).o syscalls_$(BITS).o os-Linux/
diff --git a/arch/x86/um/nommu/entry_64.S b/arch/x86/um/nommu/entry_64.S
index e9bfc7b93c84..950447dfa66b 100644
--- a/arch/x86/um/nommu/entry_64.S
+++ b/arch/x86/um/nommu/entry_64.S
@@ -89,3 +89,25 @@ ENTRY(__kernel_vsyscall)
jmp *%rcx
END(__kernel_vsyscall)
+
+// void userspace(struct uml_pt_regs *regs)
+ENTRY(userspace)
+
+ /* align the stack for x86_64 ABI */
+ and $-0x10, %rsp
+ /* Handle any immediate reschedules or signals */
+ call interrupt_end
+
+ movq current_ptregs, %rsp
+
+ POP_REGS
+
+ addq $8, %rsp /* skip orig_ax */
+ popq %r11 /* pt_regs->ip */
+ addq $8, %rsp /* skip cs */
+ addq $8, %rsp /* skip flags */
+ popq %rsp
+
+ jmp *%r11
+
+END(userspace)
diff --git a/arch/x86/um/nommu/syscalls_64.c b/arch/x86/um/nommu/syscalls_64.c
new file mode 100644
index 000000000000..c78c442aed1d
--- /dev/null
+++ b/arch/x86/um/nommu/syscalls_64.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright 2003 PathScale, Inc.
+ *
+ * Licensed under the GPL
+ */
+
+#include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+#include <asm/prctl.h> /* XXX This should get the constants from libc */
+#include <registers.h>
+#include <os.h>
+#include "syscalls.h"
+
+void arch_switch_to(struct task_struct *to)
+{
+ /*
+ * In !CONFIG_MMU, it doesn't ptrace thus,
+ * The FS_BASE/GS_BASE registers are saved here.
+ */
+ current_top_of_stack = task_top_of_stack(to);
+ current_ptregs = (long)task_pt_regs(to);
+
+ if ((to->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] == 0) ||
+ (to->mm == NULL))
+ return;
+
+ /* this changes the FS on every context switch */
+ arch_prctl(to, ARCH_SET_FS,
+ (void __user *) to->thread.regs.regs.gp[FS_BASE /
sizeof(unsigned long)]);
+}
+
+SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
+ unsigned long, prot, unsigned long, flags,
+ unsigned long, fd, unsigned long, off)
+{
+ if (off & ~PAGE_MASK)
+ return -EINVAL;
+
+ return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
+}
--
2.43.0
