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Doc: update Documentation/exception.txt

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Update Documentation/exception.txt.
Remove trailing whitespaces in it.

Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Amerigo Wang 2009-07-10 15:02:41 -07:00 committed by Linus Torvalds
parent 097041e576
commit 3697cd9aa8
1 changed files with 101 additions and 101 deletions
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14
Documentation/exception.txt
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@ -1,4 +1,4 @@
Kernel level exception handling in Linux 2.1.8
Kernel level exception handling in Linux
Commentary by Joerg Pommnitz <joerg@raleigh.ibm.com>
When a process runs in kernel mode, it often has to access user
@ -29,8 +29,8 @@ page fault handler
void do_page_fault(struct pt_regs *regs, unsigned long error_code)
in arch/i386/mm/fault.c. The parameters on the stack are set up by
the low level assembly glue in arch/i386/kernel/entry.S. The parameter
in arch/x86/mm/fault.c. The parameters on the stack are set up by
the low level assembly glue in arch/x86/kernel/entry_32.S. The parameter
regs is a pointer to the saved registers on the stack, error_code
contains a reason code for the exception.
@ -52,12 +52,12 @@ Where does fixup point to?
Since we jump to the contents of fixup, fixup obviously points
to executable code. This code is hidden inside the user access macros.
I have picked the get_user macro defined in include/asm/uaccess.h as an
example. The definition is somewhat hard to follow, so let's peek at
I have picked the get_user macro defined in arch/x86/include/asm/uaccess.h
as an example. The definition is somewhat hard to follow, so let's peek at
the code generated by the preprocessor and the compiler. I selected
the get_user call in drivers/char/console.c for a detailed examination.
the get_user call in drivers/char/sysrq.c for a detailed examination.
The original code in console.c line 1405:
The original code in sysrq.c line 587:
get_user(c, buf);
The preprocessor output (edited to become somewhat readable):