[PATCH] uml: move libc-dependent skas process handling

The serial UML OS-abstraction layer patch (um/kernel/skas dir).

This moves all systemcalls from skas/process.c file under os-Linux dir and
join skas/process.c and skas/process_kern.c files.

Signed-off-by: Gennady Sharapov <gennady.v.sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 572 insertions, 2 deletions

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 884e45751944..56ca95931b41 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -194,3 +194,8 @@ int set_signals(int enable)
 
         return(ret);
 }
+
+void os_usr1_signal(int on)
+{
+        change_sig(SIGUSR1, on);
+}
diff --git a/arch/um/os-Linux/skas/Makefile b/arch/um/os-Linux/skas/Makefile
index 79cc6c72aa92..5fd8d4dad66a 100644
--- a/arch/um/os-Linux/skas/Makefile
+++ b/arch/um/os-Linux/skas/Makefile
@@ -3,8 +3,8 @@
 # Licensed under the GPL
 #
 
-obj-y := mem.o trap.o
+obj-y := mem.o process.o trap.o
 
-USER_OBJS := mem.o trap.o
+USER_OBJS := mem.o process.o trap.o
 
 include arch/um/scripts/Makefile.rules
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
new file mode 100644
index 000000000000..f787854322c4
--- /dev/null
+++ b/arch/um/os-Linux/skas/process.c
@@ -0,0 +1,565 @@
+/*
+ * Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <sched.h>
+#include "ptrace_user.h"
+#include <sys/wait.h>
+#include <sys/mman.h>
+#include <sys/user.h>
+#include <sys/time.h>
+#include <asm/unistd.h>
+#include <asm/types.h>
+#include "user.h"
+#include "sysdep/ptrace.h"
+#include "user_util.h"
+#include "kern_util.h"
+#include "skas.h"
+#include "stub-data.h"
+#include "mm_id.h"
+#include "sysdep/sigcontext.h"
+#include "sysdep/stub.h"
+#include "os.h"
+#include "proc_mm.h"
+#include "skas_ptrace.h"
+#include "chan_user.h"
+#include "registers.h"
+#include "mem.h"
+#include "uml-config.h"
+#include "process.h"
+
+int is_skas_winch(int pid, int fd, void *data)
+{
+        if(pid != os_getpgrp())
+                return(0);
+
+        register_winch_irq(-1, fd, -1, data);
+        return(1);
+}
+
+void wait_stub_done(int pid, int sig, char * fname)
+{
+        int n, status, err;
+
+        do {
+                if ( sig != -1 ) {
+                        err = ptrace(PTRACE_CONT, pid, 0, sig);
+                        if(err)
+                                panic("%s : continue failed, errno = %d\n",
+                                      fname, errno);
+                }
+                sig = 0;
+
+                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+        } while((n >= 0) && WIFSTOPPED(status) &&
+                ((WSTOPSIG(status) == SIGVTALRM) ||
+                 /* running UML inside a detached screen can cause
+                  * SIGWINCHes
+                  */
+                 (WSTOPSIG(status) == SIGWINCH)));
+
+        if((n < 0) || !WIFSTOPPED(status) ||
+           (WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
+                unsigned long regs[HOST_FRAME_SIZE];
+
+                if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
+                        printk("Failed to get registers from stub, "
+                               "errno = %d\n", errno);
+                else {
+                        int i;
+
+                        printk("Stub registers -\n");
+                        for(i = 0; i < HOST_FRAME_SIZE; i++)
+                                printk("\t%d - %lx\n", i, regs[i]);
+                }
+                panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
+                      "pid = %d, n = %d, errno = %d, status = 0x%x\n",
+                      fname, pid, n, errno, status);
+        }
+}
+
+extern unsigned long current_stub_stack(void);
+
+void get_skas_faultinfo(int pid, struct faultinfo * fi)
+{
+        int err;
+
+        if(ptrace_faultinfo){
+                err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
+                if(err)
+                        panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
+                              "errno = %d\n", errno);
+
+                /* Special handling for i386, which has different structs */
+                if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
+                        memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
+                               sizeof(struct faultinfo) -
+                               sizeof(struct ptrace_faultinfo));
+        }
+        else {
+                wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
+
+                /* faultinfo is prepared by the stub-segv-handler at start of
+                 * the stub stack page. We just have to copy it.
+                 */
+                memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
+        }
+}
+
+static void handle_segv(int pid, union uml_pt_regs * regs)
+{
+        get_skas_faultinfo(pid, &regs->skas.faultinfo);
+        segv(regs->skas.faultinfo, 0, 1, NULL);
+}
+
+/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
+static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
+{
+        int err, status;
+
+        /* Mark this as a syscall */
+        UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
+
+        if (!local_using_sysemu)
+        {
+                err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
+                             __NR_getpid);
+                if(err < 0)
+                        panic("handle_trap - nullifying syscall failed errno = %d\n",
+                              errno);
+
+                err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
+                if(err < 0)
+                        panic("handle_trap - continuing to end of syscall failed, "
+                              "errno = %d\n", errno);
+
+                CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
+                if((err < 0) || !WIFSTOPPED(status) ||
+                   (WSTOPSIG(status) != SIGTRAP + 0x80))
+                        panic("handle_trap - failed to wait at end of syscall, "
+                              "errno = %d, status = %d\n", errno, status);
+        }
+
+        handle_syscall(regs);
+}
+
+extern int __syscall_stub_start;
+int stub_code_fd = -1;
+__u64 stub_code_offset;
+
+static int userspace_tramp(void *stack)
+{
+        void *addr;
+
+        ptrace(PTRACE_TRACEME, 0, 0, 0);
+
+        init_new_thread_signals(1);
+        enable_timer();
+
+        if(!proc_mm){
+                /* This has a pte, but it can't be mapped in with the usual
+                 * tlb_flush mechanism because this is part of that mechanism
+                 */
+                addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
+                              PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
+                              stub_code_fd, stub_code_offset);
+                if(addr == MAP_FAILED){
+                        printk("mapping stub code failed, errno = %d\n",
+                               errno);
+                        exit(1);
+                }
+
+                if(stack != NULL){
+                        int fd;
+                        __u64 offset;
+                        fd = phys_mapping(to_phys(stack), &offset);
+                        addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
+                                    PROT_READ | PROT_WRITE,
+                                    MAP_FIXED | MAP_SHARED, fd, offset);
+                        if(addr == MAP_FAILED){
+                                printk("mapping stub stack failed, "
+                                       "errno = %d\n", errno);
+                                exit(1);
+                        }
+                }
+        }
+        if(!ptrace_faultinfo){
+                unsigned long v = UML_CONFIG_STUB_CODE +
+                                  (unsigned long) stub_segv_handler -
+                                  (unsigned long) &__syscall_stub_start;
+
+                set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
+                set_handler(SIGSEGV, (void *) v, SA_ONSTACK,
+                            SIGIO, SIGWINCH, SIGALRM, SIGVTALRM,
+                            SIGUSR1, -1);
+        }
+
+        os_stop_process(os_getpid());
+        return(0);
+}
+
+/* Each element set once, and only accessed by a single processor anyway */
+#undef NR_CPUS
+#define NR_CPUS 1
+int userspace_pid[NR_CPUS];
+
+int start_userspace(unsigned long stub_stack)
+{
+        void *stack;
+        unsigned long sp;
+        int pid, status, n, flags;
+
+        if ( stub_code_fd == -1 )
+                stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
+                                            &stub_code_offset);
+
+        stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
+                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        if(stack == MAP_FAILED)
+                panic("start_userspace : mmap failed, errno = %d", errno);
+        sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
+
+        flags = CLONE_FILES | SIGCHLD;
+        if(proc_mm) flags |= CLONE_VM;
+        pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
+        if(pid < 0)
+                panic("start_userspace : clone failed, errno = %d", errno);
+
+        do {
+                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+                if(n < 0)
+                        panic("start_userspace : wait failed, errno = %d",
+                              errno);
+        } while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
+
+        if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
+                panic("start_userspace : expected SIGSTOP, got status = %d",
+                      status);
+
+        if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
+                panic("start_userspace : PTRACE_OLDSETOPTIONS failed, errno=%d\n",
+                      errno);
+
+        if(munmap(stack, PAGE_SIZE) < 0)
+                panic("start_userspace : munmap failed, errno = %d\n", errno);
+
+        return(pid);
+}
+
+void userspace(union uml_pt_regs *regs)
+{
+        int err, status, op, pid = userspace_pid[0];
+        int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
+
+        while(1){
+                restore_registers(pid, regs);
+
+                /* Now we set local_using_sysemu to be used for one loop */
+                local_using_sysemu = get_using_sysemu();
+
+                op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
+
+                err = ptrace(op, pid, 0, 0);
+                if(err)
+                        panic("userspace - could not resume userspace process, "
+                              "pid=%d, ptrace operation = %d, errno = %d\n",
+                              op, errno);
+
+                CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
+                if(err < 0)
+                        panic("userspace - waitpid failed, errno = %d\n",
+                              errno);
+
+                regs->skas.is_user = 1;
+                save_registers(pid, regs);
+                UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
+
+                if(WIFSTOPPED(status)){
+                        switch(WSTOPSIG(status)){
+                        case SIGSEGV:
+                                if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
+                                        user_signal(SIGSEGV, regs, pid);
+                                else handle_segv(pid, regs);
+                                break;
+                        case SIGTRAP + 0x80:
+                                handle_trap(pid, regs, local_using_sysemu);
+                                break;
+                        case SIGTRAP:
+                                relay_signal(SIGTRAP, regs);
+                                break;
+                        case SIGIO:
+                        case SIGVTALRM:
+                        case SIGILL:
+                        case SIGBUS:
+                        case SIGFPE:
+                        case SIGWINCH:
+                                user_signal(WSTOPSIG(status), regs, pid);
+                                break;
+                        default:
+                                printk("userspace - child stopped with signal "
+                                       "%d\n", WSTOPSIG(status));
+                        }
+                    again:
+                        pid = userspace_pid[0];
+                        interrupt_end();
+
+                        /* Avoid -ERESTARTSYS handling in host */
+                        if(PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
+                                PT_SYSCALL_NR(regs->skas.regs) = -1;
+                }
+        }
+}
+#define INIT_JMP_NEW_THREAD 0
+#define INIT_JMP_REMOVE_SIGSTACK 1
+#define INIT_JMP_CALLBACK 2
+#define INIT_JMP_HALT 3
+#define INIT_JMP_REBOOT 4
+
+int copy_context_skas0(unsigned long new_stack, int pid)
+{
+        int err;
+        unsigned long regs[MAX_REG_NR];
+        unsigned long current_stack = current_stub_stack();
+        struct stub_data *data = (struct stub_data *) current_stack;
+        struct stub_data *child_data = (struct stub_data *) new_stack;
+        __u64 new_offset;
+        int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
+
+        /* prepare offset and fd of child's stack as argument for parent's
+         * and child's mmap2 calls
+         */
+        *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
+                                      .fd       = new_fd,
+                                      .timer    = ((struct itimerval)
+                                                    { { 0, 1000000 / hz() },
+                                                      { 0, 1000000 / hz() }})});
+        get_safe_registers(regs);
+
+        /* Set parent's instruction pointer to start of clone-stub */
+        regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
+                                (unsigned long) stub_clone_handler -
+                                (unsigned long) &__syscall_stub_start;
+        regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
+                sizeof(void *);
+#ifdef __SIGNAL_FRAMESIZE
+        regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
+#endif
+        err = ptrace_setregs(pid, regs);
+        if(err < 0)
+                panic("copy_context_skas0 : PTRACE_SETREGS failed, "
+                      "pid = %d, errno = %d\n", pid, errno);
+
+        /* set a well known return code for detection of child write failure */
+        child_data->err = 12345678;
+
+        /* Wait, until parent has finished its work: read child's pid from
+         * parent's stack, and check, if bad result.
+         */
+        wait_stub_done(pid, 0, "copy_context_skas0");
+
+        pid = data->err;
+        if(pid < 0)
+                panic("copy_context_skas0 - stub-parent reports error %d\n",
+                      pid);
+
+        /* Wait, until child has finished too: read child's result from
+         * child's stack and check it.
+         */
+        wait_stub_done(pid, -1, "copy_context_skas0");
+        if (child_data->err != UML_CONFIG_STUB_DATA)
+                panic("copy_context_skas0 - stub-child reports error %d\n",
+                      child_data->err);
+
+        if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
+                   (void *)PTRACE_O_TRACESYSGOOD) < 0)
+                panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
+                      "errno = %d\n", errno);
+
+        return pid;
+}
+
+/*
+ * This is used only, if stub pages are needed, while proc_mm is
+ * availabl. Opening /proc/mm creates a new mm_context, which lacks
+ * the stub-pages. Thus, we map them using /proc/mm-fd
+ */
+void map_stub_pages(int fd, unsigned long code,
+                    unsigned long data, unsigned long stack)
+{
+        struct proc_mm_op mmop;
+        int n;
+
+        mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
+                                      .u         =
+                                      { .mmap    =
+                                        { .addr    = code,
+                                          .len     = PAGE_SIZE,
+                                          .prot    = PROT_EXEC,
+                                          .flags   = MAP_FIXED | MAP_PRIVATE,
+                                          .fd      = stub_code_fd,
+                                          .offset  = stub_code_offset
+        } } });
+        n = os_write_file(fd, &mmop, sizeof(mmop));
+        if(n != sizeof(mmop))
+                panic("map_stub_pages : /proc/mm map for code failed, "
+                      "err = %d\n", -n);
+
+        if ( stack ) {
+                __u64 map_offset;
+                int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
+                mmop = ((struct proc_mm_op)
+                                { .op        = MM_MMAP,
+                                  .u         =
+                                  { .mmap    =
+                                    { .addr    = data,
+                                      .len     = PAGE_SIZE,
+                                      .prot    = PROT_READ | PROT_WRITE,
+                                      .flags   = MAP_FIXED | MAP_SHARED,
+                                      .fd      = map_fd,
+                                      .offset  = map_offset
+                } } });
+                n = os_write_file(fd, &mmop, sizeof(mmop));
+                if(n != sizeof(mmop))
+                        panic("map_stub_pages : /proc/mm map for data failed, "
+                              "err = %d\n", -n);
+        }
+}
+
+void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
+                void (*handler)(int))
+{
+        unsigned long flags;
+        sigjmp_buf switch_buf, fork_buf;
+
+        *switch_buf_ptr = &switch_buf;
+        *fork_buf_ptr = &fork_buf;
+
+        /* Somewhat subtle - siglongjmp restores the signal mask before doing
+         * the longjmp.  This means that when jumping from one stack to another
+         * when the target stack has interrupts enabled, an interrupt may occur
+         * on the source stack.  This is bad when starting up a process because
+         * it's not supposed to get timer ticks until it has been scheduled.
+         * So, we disable interrupts around the sigsetjmp to ensure that
+         * they can't happen until we get back here where they are safe.
+         */
+        flags = get_signals();
+        block_signals();
+        if(sigsetjmp(fork_buf, 1) == 0)
+                new_thread_proc(stack, handler);
+
+        remove_sigstack();
+
+        set_signals(flags);
+}
+
+void thread_wait(void *sw, void *fb)
+{
+        sigjmp_buf buf, **switch_buf = sw, *fork_buf;
+
+        *switch_buf = &buf;
+        fork_buf = fb;
+        if(sigsetjmp(buf, 1) == 0)
+                siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
+}
+
+void switch_threads(void *me, void *next)
+{
+        sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
+
+        *me_ptr = &my_buf;
+        if(sigsetjmp(my_buf, 1) == 0)
+                siglongjmp(*next_buf, 1);
+}
+
+static sigjmp_buf initial_jmpbuf;
+
+/* XXX Make these percpu */
+static void (*cb_proc)(void *arg);
+static void *cb_arg;
+static sigjmp_buf *cb_back;
+
+int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
+{
+        sigjmp_buf **switch_buf = switch_buf_ptr;
+        int n;
+
+        set_handler(SIGWINCH, (__sighandler_t) sig_handler,
+                    SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
+                    SIGVTALRM, -1);
+
+        *fork_buf_ptr = &initial_jmpbuf;
+        n = sigsetjmp(initial_jmpbuf, 1);
+        switch(n){
+        case INIT_JMP_NEW_THREAD:
+                new_thread_proc((void *) stack, new_thread_handler);
+                break;
+        case INIT_JMP_REMOVE_SIGSTACK:
+                remove_sigstack();
+                break;
+        case INIT_JMP_CALLBACK:
+                (*cb_proc)(cb_arg);
+                siglongjmp(*cb_back, 1);
+                break;
+        case INIT_JMP_HALT:
+                kmalloc_ok = 0;
+                return(0);
+        case INIT_JMP_REBOOT:
+                kmalloc_ok = 0;
+                return(1);
+        default:
+                panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
+        }
+        siglongjmp(**switch_buf, 1);
+}
+
+void initial_thread_cb_skas(void (*proc)(void *), void *arg)
+{
+        sigjmp_buf here;
+
+        cb_proc = proc;
+        cb_arg = arg;
+        cb_back = &here;
+
+        block_signals();
+        if(sigsetjmp(here, 1) == 0)
+                siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
+        unblock_signals();
+
+        cb_proc = NULL;
+        cb_arg = NULL;
+        cb_back = NULL;
+}
+
+void halt_skas(void)
+{
+        block_signals();
+        siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
+}
+
+void reboot_skas(void)
+{
+        block_signals();
+        siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
+}
+
+void switch_mm_skas(struct mm_id *mm_idp)
+{
+        int err;
+
+#warning need cpu pid in switch_mm_skas
+        if(proc_mm){
+                err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
+                             mm_idp->u.mm_fd);
+                if(err)
+                        panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
+                              "errno = %d\n", errno);
+        }
+        else userspace_pid[0] = mm_idp->u.pid;
+}