linux-toradex.git/arch/i386/kernel/entry.S, branch v2.6.19.2

[PATCH] i386/x86-64: Work around gcc bug with noreturn functions in unwinder

2006-09-26T08:52:41+00:00

Current gcc generates calls not jumps to noreturn functions. When that happens the
return address can point to the next function, which confuses the unwinder.

This patch works around it by marking asynchronous exception
frames in contrast normal call frames in the unwind information.  Then teach
the unwinder to decode this.

For normal call frames the unwinder now subtracts one from the address which avoids
this problem.  The standard libgcc unwinder uses the same trick.

It doesn't include adjustment of the printed address (i.e. for the original
example, it'd still be kernel_math_error+0 that gets displayed, but the
unwinder wouldn't get confused anymore.

This only works with binutils 2.6.17+ and some versions of H.J.Lu's 2.6.16
unfortunately because earlier binutils don't support .cfi_signal_frame

[AK: added automatic detection of the new binutils and wrote description]

Signed-off-by: Jan Beulich 
Signed-off-by: Andi Kleen

[PATCH] i386: Allow a kernel not to be in ring 0

2006-09-26T08:52:39+00:00

We allow for the fact that the guest kernel may not run in ring 0.  This
requires some abstraction in a few places when setting %cs or checking
privilege level (user vs kernel).

This is Chris' [RFC PATCH 15/33] move segment checks to subarch, except rather
than using #define USER_MODE_MASK which depends on a config option, we use
Zach's more flexible approach of assuming ring 3 == userspace.  I also used
"get_kernel_rpl()" over "get_kernel_cs()" because I think it reads better in
the code...

1) Remove the hardcoded 3 and introduce #define SEGMENT_RPL_MASK 3 2) Add a
get_kernel_rpl() macro, and don't assume it's zero.

And:

Clean up of patch for letting kernel run other than ring 0:

a. Add some comments about the SEGMENT_IS_*_CODE() macros.
b. Add a USER_RPL macro.  (Code was comparing a value to a mask
   in some places and to the magic number 3 in other places.)
c. Add macros for table indicator field and use them.
d. Change the entry.S tests for LDT stack segment to use the macros

Signed-off-by: Rusty Russell 
Signed-off-by: Zachary Amsden 
Signed-off-by: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Andi Kleen

[PATCH] i386: Abstract sensitive instructions

2006-09-26T08:52:39+00:00

Abstract sensitive instructions in assembler code, replacing them with macros
(which currently are #defined to the native versions).  We use long names:
assembler is case-insensitive, so if something goes wrong and macros do not
expand, it would assemble anyway.

Resulting object files are exactly the same as before.

Signed-off-by: Rusty Russell 
Signed-off-by: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Andi Kleen

[PATCH] i386: annotate FIX_STACK() and the rest of nmi()

2006-09-26T08:52:37+00:00

In i386's entry.S, FIX_STACK() needs annotation because it
replaces the stack pointer.  And the rest of nmi() needs
annotation in order to compile with these new annotations.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen

[PATCH] i386: Disallow kprobes on NMI handlers

2006-09-26T08:52:36+00:00

A kprobe executes IRET early and that could cause NMI recursion and stack
corruption.

Note: This problem was originally spotted and solved by Andi Kleen in the
x86_64 architecture. This patch is an adaption of his patch for i386.

AK: Merged with current code which was a bit different.
AK: Removed printk in nmi handler that shouldn't be there in the first time
AK: Added missing include.
AK: added KPROBES_END

Signed-off-by: Fernando Vazquez 
Signed-off-by: Andi Kleen

[PATCH] i386: move kernel_thread_helper into entry.S

2006-09-26T08:52:35+00:00

And add proper CFI annotation to it which was previously
impossible. This prevents "stuck" messages by the dwarf2 unwinder
when reaching the top of a kernel stack.

Includes feedback from Jan Beulich

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen

[PATCH] x86: error_code is not safe for kprobes

2006-09-26T08:52:34+00:00

This patch moves the entry.S:error_entry to .kprobes.text section,
since code marked unsafe for kprobes jumps directly to entry.S::error_entry,
that must be marked unsafe as well.
This patch also moves all the ".previous.text" asm directives to ".previous"
for kprobes section.

AK: Following a similar i386 patch from Chuck Ebbert
AK: Also merged Jeremy's fix in.

+From: Jeremy Fitzhardinge 

KPROBE_ENTRY does a .section .kprobes.text, and expects its users to
do a .previous at the end of the function.

Unfortunately, if any code within the function switches sections, for
example .fixup, then the .previous ends up putting all subsequent code
into .fixup.  Worse, any subsequent .fixup code gets intermingled with
the code its supposed to be fixing (which is also in .fixup).  It's
surprising this didn't cause more havok.

The fix is to use .pushsection/.popsection, so this stuff nests
properly.  A further cleanup would be to get rid of all
.section/.previous pairs, since they're inherently fragile.

+From: Chuck Ebbert <76306.1226@compuserve.com>

Because code marked unsafe for kprobes jumps directly to
entry.S::error_code, that must be marked unsafe as well.
The easiest way to do that is to move the page fault entry
point to just before error_code and let it inherit the same
section.

Also moved all the ".previous" asm directives for kprobes
sections to column 1 and removed ".text" from them.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen

x86: save/restore eflags in context switch

2006-09-18T23:20:40+00:00

(And reset it on new thread creation)

It turns out that eflags is important to save and restore not just
because of iopl, but due to the magic bits like the NT bit, which we
don't want leaking between different threads.

Tested-by: Mike Galbraith 
Signed-off-by: Linus Torvalds

[PATCH] Fix trivial unwind info bug

2006-07-31T20:28:43+00:00

CFA needs to be adjusted upwards for push, and downwards for pop.
arch/i386/kernel/entry.S gets it wrong in one place.

Signed-off-by: Markus Armbruster 
Acked-by: Jan Beulich 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: irqtrace subsystem, i386 support

2006-07-03T22:27:03+00:00

Add irqflags-tracing support to i386.

Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds