546fe1cbf9
The current code doesn't handle well general protection faults on the host - it thinks that cr2 is always the address of a page fault. While actually, on general protection faults, that address is not accessible, so we'd better assume we couldn't satisfy the fault. Currently instead we think we've fixed it, so we go back, retry the instruction and fault again endlessly. This leads to the kernel hanging when doing copy_from_user(dest, -1, ...) in TT mode, since reading *(-1) causes a GFP, and we don't support kernel preemption. Thanks to Luo Xin for testing UML with LTP and reporting the failures he got. Cc: Luo Xin <luothing@sina.com> Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
106 lines
2.6 KiB
C
106 lines
2.6 KiB
C
/*
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* Copyright (C) 2001 Chris Emerson (cemerson@chiark.greenend.org.uk)
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* Copyright (C) 2001 Jeff Dike (jdike@karaya.com)
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* Licensed under the GPL
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*/
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#include <setjmp.h>
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#include <string.h>
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#include "user_util.h"
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#include "uml_uaccess.h"
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#include "task.h"
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#include "kern_util.h"
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int __do_copy_from_user(void *to, const void *from, int n,
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void **fault_addr, void **fault_catcher)
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{
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struct tt_regs save = TASK_REGS(get_current())->tt;
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unsigned long fault;
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int faulted;
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fault = __do_user_copy(to, from, n, fault_addr, fault_catcher,
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__do_copy, &faulted);
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TASK_REGS(get_current())->tt = save;
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if(!faulted)
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return 0;
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else if (fault)
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return n - (fault - (unsigned long) from);
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else
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/* In case of a general protection fault, we don't have the
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* fault address, so NULL is used instead. Pretend we didn't
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* copy anything. */
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return n;
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}
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static void __do_strncpy(void *dst, const void *src, int count)
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{
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strncpy(dst, src, count);
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}
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int __do_strncpy_from_user(char *dst, const char *src, unsigned long count,
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void **fault_addr, void **fault_catcher)
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{
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struct tt_regs save = TASK_REGS(get_current())->tt;
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unsigned long fault;
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int faulted;
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fault = __do_user_copy(dst, src, count, fault_addr, fault_catcher,
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__do_strncpy, &faulted);
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TASK_REGS(get_current())->tt = save;
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if(!faulted) return(strlen(dst));
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else return(-1);
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}
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static void __do_clear(void *to, const void *from, int n)
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{
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memset(to, 0, n);
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}
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int __do_clear_user(void *mem, unsigned long len,
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void **fault_addr, void **fault_catcher)
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{
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struct tt_regs save = TASK_REGS(get_current())->tt;
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unsigned long fault;
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int faulted;
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fault = __do_user_copy(mem, NULL, len, fault_addr, fault_catcher,
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__do_clear, &faulted);
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TASK_REGS(get_current())->tt = save;
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if(!faulted) return(0);
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else return(len - (fault - (unsigned long) mem));
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}
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int __do_strnlen_user(const char *str, unsigned long n,
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void **fault_addr, void **fault_catcher)
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{
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struct tt_regs save = TASK_REGS(get_current())->tt;
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int ret;
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unsigned long *faddrp = (unsigned long *)fault_addr;
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sigjmp_buf jbuf;
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*fault_catcher = &jbuf;
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if(sigsetjmp(jbuf, 1) == 0)
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ret = strlen(str) + 1;
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else ret = *faddrp - (unsigned long) str;
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*fault_addr = NULL;
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*fault_catcher = NULL;
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TASK_REGS(get_current())->tt = save;
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return ret;
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}
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/*
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* Overrides for Emacs so that we follow Linus's tabbing style.
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* Emacs will notice this stuff at the end of the file and automatically
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* adjust the settings for this buffer only. This must remain at the end
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* of the file.
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* ---------------------------------------------------------------------------
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* Local variables:
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* c-file-style: "linux"
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* End:
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*/
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