forked from Minki/linux
5b7b15afee
With Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> UML skas0 stub has been miscompiling for many people (incidentally not the authors), depending on the used GCC versions. I think (and testing on some GCC versions shows) this patch avoids the fundamental issue which is behind this, namely gcc using the stack when we have just replaced it, behind gcc's back. The remapping and storage of the return value is hidden in a blob of asm, hopefully giving gcc no room for creativity. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
55 lines
1.3 KiB
C
55 lines
1.3 KiB
C
#include <sched.h>
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#include <signal.h>
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#include <sys/mman.h>
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#include <sys/time.h>
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#include <asm/unistd.h>
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#include <asm/page.h>
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#include "ptrace_user.h"
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#include "skas.h"
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#include "stub-data.h"
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#include "uml-config.h"
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#include "sysdep/stub.h"
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#include "kern_constants.h"
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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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struct stub_data *data = (struct stub_data *) UML_CONFIG_STUB_DATA;
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long err;
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err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
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UML_CONFIG_STUB_DATA + UM_KERN_PAGE_SIZE / 2 -
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sizeof(void *));
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if(err != 0)
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goto out;
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err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
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if(err)
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goto out;
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err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
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(long) &data->timer, 0);
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if(err)
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goto out;
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remap_stack(data->fd, data->offset);
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goto done;
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out:
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/* save current result.
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* Parent: pid;
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* child: retcode of mmap already saved and it jumps around this
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* assignment
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*/
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data->err = err;
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done:
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trap_myself();
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}
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