9f0b4807a4
The userspace stacks mostly have a stack (and in the case of the syscall stub we can just set their stack pointer) that points to the location of the stub data page already. Rework the stubs to use the stack pointer to derive the start of the data page, rather than requiring it to be hard-coded. In the clone stub, also integrate the int3 into the stack remap, since we really must not use the stack while we remap it. This prepares for putting the stub at a variable location that's not part of the normal address space of the userspace processes running inside the UML machine. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
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* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#include <signal.h>
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#include <sched.h>
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#include <asm/unistd.h>
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#include <sys/time.h>
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#include <as-layout.h>
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#include <ptrace_user.h>
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#include <stub-data.h>
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#include <sysdep/stub.h>
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/*
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* This is in a separate file because it needs to be compiled with any
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* extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
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*
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* Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
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* on some systems.
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*/
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void __attribute__ ((__section__ (".__syscall_stub")))
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stub_clone_handler(void)
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{
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int stack;
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struct stub_data *data = (void *) ((unsigned long)&stack & ~(UM_KERN_PAGE_SIZE - 1));
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long err;
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err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
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(unsigned long)data + UM_KERN_PAGE_SIZE / 2 - sizeof(void *));
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if (err) {
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data->parent_err = err;
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goto done;
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}
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err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
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if (err) {
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data->child_err = err;
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goto done;
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}
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remap_stack_and_trap();
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done:
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trap_myself();
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}
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