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720 lines
18 KiB
720 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2015 Thomas Meyer ([email protected]) |
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* Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
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*/ |
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|
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#include <stdlib.h> |
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#include <unistd.h> |
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#include <sched.h> |
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#include <errno.h> |
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#include <string.h> |
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#include <sys/mman.h> |
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#include <sys/wait.h> |
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#include <asm/unistd.h> |
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#include <as-layout.h> |
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#include <init.h> |
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#include <kern_util.h> |
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#include <mem.h> |
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#include <os.h> |
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#include <ptrace_user.h> |
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#include <registers.h> |
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#include <skas.h> |
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#include <sysdep/stub.h> |
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#include <linux/threads.h> |
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int is_skas_winch(int pid, int fd, void *data) |
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{ |
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return pid == getpgrp(); |
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} |
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static const char *ptrace_reg_name(int idx) |
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{ |
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#define R(n) case HOST_##n: return #n |
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switch (idx) { |
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#ifdef __x86_64__ |
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R(BX); |
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R(CX); |
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R(DI); |
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R(SI); |
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R(DX); |
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R(BP); |
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R(AX); |
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R(R8); |
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R(R9); |
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R(R10); |
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R(R11); |
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R(R12); |
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R(R13); |
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R(R14); |
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R(R15); |
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R(ORIG_AX); |
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R(CS); |
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R(SS); |
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R(EFLAGS); |
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#elif defined(__i386__) |
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R(IP); |
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R(SP); |
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R(EFLAGS); |
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R(AX); |
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R(BX); |
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R(CX); |
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R(DX); |
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R(SI); |
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R(DI); |
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R(BP); |
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R(CS); |
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R(SS); |
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R(DS); |
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R(FS); |
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R(ES); |
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R(GS); |
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R(ORIG_AX); |
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#endif |
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} |
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return ""; |
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} |
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static int ptrace_dump_regs(int pid) |
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{ |
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unsigned long regs[MAX_REG_NR]; |
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int i; |
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if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) |
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return -errno; |
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printk(UM_KERN_ERR "Stub registers -\n"); |
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for (i = 0; i < ARRAY_SIZE(regs); i++) { |
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const char *regname = ptrace_reg_name(i); |
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printk(UM_KERN_ERR "\t%s\t(%2d): %lx\n", regname, i, regs[i]); |
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} |
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return 0; |
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} |
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/* |
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* Signals that are OK to receive in the stub - we'll just continue it. |
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* SIGWINCH will happen when UML is inside a detached screen. |
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*/ |
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#define STUB_SIG_MASK ((1 << SIGALRM) | (1 << SIGWINCH)) |
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/* Signals that the stub will finish with - anything else is an error */ |
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#define STUB_DONE_MASK (1 << SIGTRAP) |
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void wait_stub_done(int pid) |
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{ |
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int n, status, err; |
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while (1) { |
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); |
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if ((n < 0) || !WIFSTOPPED(status)) |
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goto bad_wait; |
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if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0) |
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break; |
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err = ptrace(PTRACE_CONT, pid, 0, 0); |
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if (err) { |
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printk(UM_KERN_ERR "wait_stub_done : continue failed, " |
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"errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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} |
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if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0) |
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return; |
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bad_wait: |
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err = ptrace_dump_regs(pid); |
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if (err) |
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printk(UM_KERN_ERR "Failed to get registers from stub, " |
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"errno = %d\n", -err); |
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printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, " |
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"pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno, |
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status); |
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fatal_sigsegv(); |
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} |
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extern unsigned long current_stub_stack(void); |
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static void get_skas_faultinfo(int pid, struct faultinfo *fi, unsigned long *aux_fp_regs) |
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{ |
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int err; |
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err = get_fp_registers(pid, aux_fp_regs); |
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if (err < 0) { |
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printk(UM_KERN_ERR "save_fp_registers returned %d\n", |
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err); |
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fatal_sigsegv(); |
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} |
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err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV); |
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if (err) { |
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printk(UM_KERN_ERR "Failed to continue stub, pid = %d, " |
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"errno = %d\n", pid, errno); |
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fatal_sigsegv(); |
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} |
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wait_stub_done(pid); |
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/* |
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* faultinfo is prepared by the stub_segv_handler at start of |
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* the stub stack page. We just have to copy it. |
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*/ |
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memcpy(fi, (void *)current_stub_stack(), sizeof(*fi)); |
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err = put_fp_registers(pid, aux_fp_regs); |
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if (err < 0) { |
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printk(UM_KERN_ERR "put_fp_registers returned %d\n", |
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err); |
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fatal_sigsegv(); |
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} |
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} |
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static void handle_segv(int pid, struct uml_pt_regs *regs, unsigned long *aux_fp_regs) |
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{ |
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get_skas_faultinfo(pid, ®s->faultinfo, aux_fp_regs); |
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segv(regs->faultinfo, 0, 1, NULL); |
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} |
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/* |
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* To use the same value of using_sysemu as the caller, ask it that value |
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* (in local_using_sysemu |
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*/ |
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static void handle_trap(int pid, struct uml_pt_regs *regs, |
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int local_using_sysemu) |
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{ |
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int err, status; |
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if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END)) |
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fatal_sigsegv(); |
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if (!local_using_sysemu) |
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{ |
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err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, |
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__NR_getpid); |
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if (err < 0) { |
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printk(UM_KERN_ERR "handle_trap - nullifying syscall " |
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"failed, errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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err = ptrace(PTRACE_SYSCALL, pid, 0, 0); |
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if (err < 0) { |
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printk(UM_KERN_ERR "handle_trap - continuing to end of " |
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"syscall failed, errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); |
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if ((err < 0) || !WIFSTOPPED(status) || |
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(WSTOPSIG(status) != SIGTRAP + 0x80)) { |
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err = ptrace_dump_regs(pid); |
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if (err) |
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printk(UM_KERN_ERR "Failed to get registers " |
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"from process, errno = %d\n", -err); |
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printk(UM_KERN_ERR "handle_trap - failed to wait at " |
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"end of syscall, errno = %d, status = %d\n", |
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errno, status); |
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fatal_sigsegv(); |
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} |
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} |
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handle_syscall(regs); |
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} |
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extern char __syscall_stub_start[]; |
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/** |
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* userspace_tramp() - userspace trampoline |
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* @stack: pointer to the new userspace stack page, can be NULL, if? FIXME: |
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* |
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* The userspace trampoline is used to setup a new userspace process in start_userspace() after it was clone()'ed. |
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* This function will run on a temporary stack page. |
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* It ptrace()'es itself, then |
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* Two pages are mapped into the userspace address space: |
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* - STUB_CODE (with EXEC), which contains the skas stub code |
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* - STUB_DATA (with R/W), which contains a data page that is used to transfer certain data between the UML userspace process and the UML kernel. |
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* Also for the userspace process a SIGSEGV handler is installed to catch pagefaults in the userspace process. |
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* And last the process stops itself to give control to the UML kernel for this userspace process. |
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* |
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* Return: Always zero, otherwise the current userspace process is ended with non null exit() call |
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*/ |
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static int userspace_tramp(void *stack) |
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{ |
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void *addr; |
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int fd; |
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unsigned long long offset; |
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ptrace(PTRACE_TRACEME, 0, 0, 0); |
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signal(SIGTERM, SIG_DFL); |
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signal(SIGWINCH, SIG_IGN); |
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fd = phys_mapping(to_phys(__syscall_stub_start), &offset); |
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addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE, |
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PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset); |
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if (addr == MAP_FAILED) { |
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printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, " |
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"errno = %d\n", STUB_CODE, errno); |
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exit(1); |
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} |
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if (stack != NULL) { |
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fd = phys_mapping(to_phys(stack), &offset); |
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addr = mmap((void *) STUB_DATA, |
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UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE, |
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MAP_FIXED | MAP_SHARED, fd, offset); |
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if (addr == MAP_FAILED) { |
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printk(UM_KERN_ERR "mapping segfault stack " |
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"at 0x%lx failed, errno = %d\n", |
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STUB_DATA, errno); |
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exit(1); |
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} |
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} |
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if (stack != NULL) { |
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struct sigaction sa; |
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unsigned long v = STUB_CODE + |
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(unsigned long) stub_segv_handler - |
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(unsigned long) __syscall_stub_start; |
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set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE); |
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sigemptyset(&sa.sa_mask); |
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sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO; |
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sa.sa_sigaction = (void *) v; |
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sa.sa_restorer = NULL; |
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if (sigaction(SIGSEGV, &sa, NULL) < 0) { |
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printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV " |
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"handler failed - errno = %d\n", errno); |
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exit(1); |
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} |
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} |
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kill(os_getpid(), SIGSTOP); |
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return 0; |
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} |
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int userspace_pid[NR_CPUS]; |
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int kill_userspace_mm[NR_CPUS]; |
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/** |
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* start_userspace() - prepare a new userspace process |
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* @stub_stack: pointer to the stub stack. Can be NULL, if? FIXME: |
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* |
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* Setups a new temporary stack page that is used while userspace_tramp() runs |
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* Clones the kernel process into a new userspace process, with FDs only. |
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* |
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* Return: When positive: the process id of the new userspace process, |
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* when negative: an error number. |
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* FIXME: can PIDs become negative?! |
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*/ |
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int start_userspace(unsigned long stub_stack) |
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{ |
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void *stack; |
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unsigned long sp; |
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int pid, status, n, flags, err; |
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/* setup a temporary stack page */ |
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stack = mmap(NULL, UM_KERN_PAGE_SIZE, |
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PROT_READ | PROT_WRITE | PROT_EXEC, |
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
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if (stack == MAP_FAILED) { |
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err = -errno; |
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printk(UM_KERN_ERR "start_userspace : mmap failed, " |
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"errno = %d\n", errno); |
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return err; |
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} |
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/* set stack pointer to the end of the stack page, so it can grow downwards */ |
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sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *); |
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flags = CLONE_FILES | SIGCHLD; |
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/* clone into new userspace process */ |
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pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack); |
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if (pid < 0) { |
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err = -errno; |
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printk(UM_KERN_ERR "start_userspace : clone failed, " |
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"errno = %d\n", errno); |
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return err; |
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} |
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do { |
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); |
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if (n < 0) { |
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err = -errno; |
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printk(UM_KERN_ERR "start_userspace : wait failed, " |
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"errno = %d\n", errno); |
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goto out_kill; |
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} |
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} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGALRM)); |
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if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) { |
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err = -EINVAL; |
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printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got " |
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"status = %d\n", status); |
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goto out_kill; |
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} |
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if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, |
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(void *) PTRACE_O_TRACESYSGOOD) < 0) { |
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err = -errno; |
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printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS " |
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"failed, errno = %d\n", errno); |
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goto out_kill; |
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} |
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if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) { |
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err = -errno; |
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printk(UM_KERN_ERR "start_userspace : munmap failed, " |
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"errno = %d\n", errno); |
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goto out_kill; |
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} |
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return pid; |
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out_kill: |
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os_kill_ptraced_process(pid, 1); |
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return err; |
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} |
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void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs) |
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{ |
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int err, status, op, pid = userspace_pid[0]; |
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/* To prevent races if using_sysemu changes under us.*/ |
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int local_using_sysemu; |
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siginfo_t si; |
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/* Handle any immediate reschedules or signals */ |
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interrupt_end(); |
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while (1) { |
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if (kill_userspace_mm[0]) |
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fatal_sigsegv(); |
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/* |
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* This can legitimately fail if the process loads a |
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* bogus value into a segment register. It will |
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* segfault and PTRACE_GETREGS will read that value |
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* out of the process. However, PTRACE_SETREGS will |
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* fail. In this case, there is nothing to do but |
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* just kill the process. |
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*/ |
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if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp)) { |
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printk(UM_KERN_ERR "userspace - ptrace set regs " |
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"failed, errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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if (put_fp_registers(pid, regs->fp)) { |
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printk(UM_KERN_ERR "userspace - ptrace set fp regs " |
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"failed, errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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/* Now we set local_using_sysemu to be used for one loop */ |
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local_using_sysemu = get_using_sysemu(); |
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op = SELECT_PTRACE_OPERATION(local_using_sysemu, |
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singlestepping(NULL)); |
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if (ptrace(op, pid, 0, 0)) { |
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printk(UM_KERN_ERR "userspace - ptrace continue " |
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"failed, op = %d, errno = %d\n", op, errno); |
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fatal_sigsegv(); |
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} |
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CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); |
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if (err < 0) { |
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printk(UM_KERN_ERR "userspace - wait failed, " |
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"errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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regs->is_user = 1; |
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if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) { |
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printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, " |
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"errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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if (get_fp_registers(pid, regs->fp)) { |
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printk(UM_KERN_ERR "userspace - get_fp_registers failed, " |
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"errno = %d\n", errno); |
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fatal_sigsegv(); |
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} |
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UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */ |
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if (WIFSTOPPED(status)) { |
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int sig = WSTOPSIG(status); |
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/* These signal handlers need the si argument. |
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* The SIGIO and SIGALARM handlers which constitute the |
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* majority of invocations, do not use it. |
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*/ |
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switch (sig) { |
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case SIGSEGV: |
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case SIGTRAP: |
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case SIGILL: |
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case SIGBUS: |
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case SIGFPE: |
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case SIGWINCH: |
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ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si); |
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break; |
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} |
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switch (sig) { |
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case SIGSEGV: |
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if (PTRACE_FULL_FAULTINFO) { |
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get_skas_faultinfo(pid, |
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®s->faultinfo, aux_fp_regs); |
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(*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si, |
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regs); |
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} |
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else handle_segv(pid, regs, aux_fp_regs); |
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break; |
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case SIGTRAP + 0x80: |
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handle_trap(pid, regs, local_using_sysemu); |
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break; |
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case SIGTRAP: |
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relay_signal(SIGTRAP, (struct siginfo *)&si, regs); |
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break; |
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case SIGALRM: |
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break; |
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case SIGIO: |
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case SIGILL: |
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case SIGBUS: |
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case SIGFPE: |
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case SIGWINCH: |
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block_signals_trace(); |
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(*sig_info[sig])(sig, (struct siginfo *)&si, regs); |
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unblock_signals_trace(); |
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break; |
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default: |
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printk(UM_KERN_ERR "userspace - child stopped " |
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"with signal %d\n", sig); |
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fatal_sigsegv(); |
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} |
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pid = userspace_pid[0]; |
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interrupt_end(); |
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|
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/* Avoid -ERESTARTSYS handling in host */ |
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if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET) |
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PT_SYSCALL_NR(regs->gp) = -1; |
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} |
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} |
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} |
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static unsigned long thread_regs[MAX_REG_NR]; |
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static unsigned long thread_fp_regs[FP_SIZE]; |
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static int __init init_thread_regs(void) |
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{ |
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get_safe_registers(thread_regs, thread_fp_regs); |
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/* Set parent's instruction pointer to start of clone-stub */ |
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thread_regs[REGS_IP_INDEX] = STUB_CODE + |
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(unsigned long) stub_clone_handler - |
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(unsigned long) __syscall_stub_start; |
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thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE - |
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sizeof(void *); |
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#ifdef __SIGNAL_FRAMESIZE |
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thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE; |
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#endif |
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return 0; |
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} |
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__initcall(init_thread_regs); |
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int copy_context_skas0(unsigned long new_stack, int pid) |
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{ |
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int err; |
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unsigned long current_stack = current_stub_stack(); |
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struct stub_data *data = (struct stub_data *) current_stack; |
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struct stub_data *child_data = (struct stub_data *) new_stack; |
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unsigned long long new_offset; |
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int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset); |
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|
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/* |
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* prepare offset and fd of child's stack as argument for parent's |
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* and child's mmap2 calls |
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*/ |
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*data = ((struct stub_data) { |
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.offset = MMAP_OFFSET(new_offset), |
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.fd = new_fd, |
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.parent_err = -ESRCH, |
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.child_err = 0, |
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}); |
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*child_data = ((struct stub_data) { |
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.child_err = -ESRCH, |
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}); |
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err = ptrace_setregs(pid, thread_regs); |
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if (err < 0) { |
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err = -errno; |
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printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS " |
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"failed, pid = %d, errno = %d\n", pid, -err); |
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return err; |
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} |
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err = put_fp_registers(pid, thread_fp_regs); |
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if (err < 0) { |
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printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers " |
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"failed, pid = %d, err = %d\n", pid, err); |
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return err; |
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} |
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|
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/* |
|
* Wait, until parent has finished its work: read child's pid from |
|
* parent's stack, and check, if bad result. |
|
*/ |
|
err = ptrace(PTRACE_CONT, pid, 0, 0); |
|
if (err) { |
|
err = -errno; |
|
printk(UM_KERN_ERR "Failed to continue new process, pid = %d, " |
|
"errno = %d\n", pid, errno); |
|
return err; |
|
} |
|
|
|
wait_stub_done(pid); |
|
|
|
pid = data->parent_err; |
|
if (pid < 0) { |
|
printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports " |
|
"error %d\n", -pid); |
|
return pid; |
|
} |
|
|
|
/* |
|
* Wait, until child has finished too: read child's result from |
|
* child's stack and check it. |
|
*/ |
|
wait_stub_done(pid); |
|
if (child_data->child_err != STUB_DATA) { |
|
printk(UM_KERN_ERR "copy_context_skas0 - stub-child %d reports " |
|
"error %ld\n", pid, data->child_err); |
|
err = data->child_err; |
|
goto out_kill; |
|
} |
|
|
|
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, |
|
(void *)PTRACE_O_TRACESYSGOOD) < 0) { |
|
err = -errno; |
|
printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS " |
|
"failed, errno = %d\n", errno); |
|
goto out_kill; |
|
} |
|
|
|
return pid; |
|
|
|
out_kill: |
|
os_kill_ptraced_process(pid, 1); |
|
return err; |
|
} |
|
|
|
void new_thread(void *stack, jmp_buf *buf, void (*handler)(void)) |
|
{ |
|
(*buf)[0].JB_IP = (unsigned long) handler; |
|
(*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE - |
|
sizeof(void *); |
|
} |
|
|
|
#define INIT_JMP_NEW_THREAD 0 |
|
#define INIT_JMP_CALLBACK 1 |
|
#define INIT_JMP_HALT 2 |
|
#define INIT_JMP_REBOOT 3 |
|
|
|
void switch_threads(jmp_buf *me, jmp_buf *you) |
|
{ |
|
if (UML_SETJMP(me) == 0) |
|
UML_LONGJMP(you, 1); |
|
} |
|
|
|
static jmp_buf initial_jmpbuf; |
|
|
|
/* XXX Make these percpu */ |
|
static void (*cb_proc)(void *arg); |
|
static void *cb_arg; |
|
static jmp_buf *cb_back; |
|
|
|
int start_idle_thread(void *stack, jmp_buf *switch_buf) |
|
{ |
|
int n; |
|
|
|
set_handler(SIGWINCH); |
|
|
|
/* |
|
* Can't use UML_SETJMP or UML_LONGJMP here because they save |
|
* and restore signals, with the possible side-effect of |
|
* trying to handle any signals which came when they were |
|
* blocked, which can't be done on this stack. |
|
* Signals must be blocked when jumping back here and restored |
|
* after returning to the jumper. |
|
*/ |
|
n = setjmp(initial_jmpbuf); |
|
switch (n) { |
|
case INIT_JMP_NEW_THREAD: |
|
(*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup; |
|
(*switch_buf)[0].JB_SP = (unsigned long) stack + |
|
UM_THREAD_SIZE - sizeof(void *); |
|
break; |
|
case INIT_JMP_CALLBACK: |
|
(*cb_proc)(cb_arg); |
|
longjmp(*cb_back, 1); |
|
break; |
|
case INIT_JMP_HALT: |
|
kmalloc_ok = 0; |
|
return 0; |
|
case INIT_JMP_REBOOT: |
|
kmalloc_ok = 0; |
|
return 1; |
|
default: |
|
printk(UM_KERN_ERR "Bad sigsetjmp return in " |
|
"start_idle_thread - %d\n", n); |
|
fatal_sigsegv(); |
|
} |
|
longjmp(*switch_buf, 1); |
|
|
|
/* unreachable */ |
|
printk(UM_KERN_ERR "impossible long jump!"); |
|
fatal_sigsegv(); |
|
return 0; |
|
} |
|
|
|
void initial_thread_cb_skas(void (*proc)(void *), void *arg) |
|
{ |
|
jmp_buf here; |
|
|
|
cb_proc = proc; |
|
cb_arg = arg; |
|
cb_back = &here; |
|
|
|
block_signals_trace(); |
|
if (UML_SETJMP(&here) == 0) |
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK); |
|
unblock_signals_trace(); |
|
|
|
cb_proc = NULL; |
|
cb_arg = NULL; |
|
cb_back = NULL; |
|
} |
|
|
|
void halt_skas(void) |
|
{ |
|
block_signals_trace(); |
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT); |
|
} |
|
|
|
void reboot_skas(void) |
|
{ |
|
block_signals_trace(); |
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT); |
|
} |
|
|
|
void __switch_mm(struct mm_id *mm_idp) |
|
{ |
|
userspace_pid[0] = mm_idp->u.pid; |
|
kill_userspace_mm[0] = mm_idp->kill; |
|
}
|
|
|