linux-toradex.git/arch/um/os-Linux, branch v2.6.19.2

[PATCH] uml: make execvp safe for our usage

2006-11-25T21:28:34+00:00

Reimplement execvp for our purposes - after we call fork() it is fundamentally
unsafe to use the kernel allocator - current is not valid there.  So we simply
pass to our modified execvp() a preallocated buffer.  This fixes a real bug
and works very well in testing (I've seen indirectly warning messages from the
forked thread - they went on the pipe connected to its stdout and where read
as a number by UML, when calling read_output().  I verified the obtained
number corresponded to "BUG:").

The added use of __cant_sleep() is not a new bug since __cant_sleep() is
already used in the same function - passing an atomicity parameter would be
better but it would require huge change, stating that this function must not
be called in atomic context and can sleep is a better idea (will make sure of
this gradually).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Acked-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: include tidying

2006-11-03T20:27:59+00:00

In order to get the __NR_* constants, we need sys/syscall.h.
linux/unistd.h works as well since it includes syscall.h, however syscall.h
is more parsimonious.  We were inconsistent in this, and this patch adds
syscall.h includes where necessary and removes linux/unistd.h includes
where they are not needed.

asm/unistd.h also includes the __NR_* constants, but these are not the
glibc-sanctioned ones, so this also removes one such inclusion.

Signed-off-by: Jeff Dike 
Cc: Paolo 'Blaisorblade' Giarrusso 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: fix I/O hang

2006-11-03T20:27:58+00:00

Fix a UML hang in which everything would just stop until some I/O happened
- a ping, someone whacking the keyboard - at which point everything would
start up again as though nothing had happened.

The cause was gcc reordering some code which absolutely needed to be
executed in the order in the source.  When unblock_signals switches signals
from off to on, it needs to see if any interrupts had happened in the
critical section.  The interrupt handlers check signals_enabled - if it is
zero, then the handler adds a bit to the "pending" bitmask and returns.
unblock_signals checks this mask to see if any signals need to be
delivered.

The crucial part is this:
	signals_enabled = 1;
	save_pending = pending;
	if(save_pending == 0)
		return;
	pending = 0;

In order to avoid an interrupt arriving between reading pending and setting
it to zero, in which case, the record of the interrupt would be erased,
signals are enabled.

What happened was that gcc reordered this so that 'save_pending = pending'
came before 'signals_enabled = 1', creating a one-instruction window within
which an interrupt could arrive, set its bit in pending, and have it be
immediately erased.

When the I/O workload is purely disk-based, the loss of a block device
interrupt stops the entire I/O system because the next block request will
wait for the current one to finish.  Thus the system hangs until something
else causes some I/O to arrive, such as a network packet or console input.

The fix to this particular problem is a memory barrier between enabling
signals and reading the pending signal mask.  An xchg would also probably
work.

Looking over this code for similar problems led me to do a few more
things:

- make signals_enabled and pending volatile so that they don't get cached
  in registers

- add an mb() to the return paths of block_signals and unblock_signals so
  that the modification of signals_enabled doesn't get shuffled into the
  caller in the event that these are inlined in the future.

Signed-off-by: Jeff Dike 
Cc: Paolo 'Blaisorblade' Giarrusso 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Fix "Remove the use of _syscallX macros in UML"

2006-10-30T20:08:41+00:00

Fix commit 5f4c6bc1f369f20807a8e753c2308d1629478c61: it spits out warnings
about missing syscall prototype (it is in ) and it does not
recognize that two uses of _syscallX are to be resolved against kernel
headers in the source tree, not against _syscallX; they in fact do not
compile and would not work anyway.

If _syscallX macros will be removed from the kernel tree altogether, the
only reasonable solution for that piece of code is switching to open-coded
inline assembly (it's remapping the whole executable from memory, except
the page containing this code).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: cleanup run_helper() API to fix a leak

2006-10-20T17:26:36+00:00

Freeing the stack is left uselessly to the caller of run_helper in some cases
- this is taken from run_helper_thread, but here it is useless, so no caller
needs it and the only place where this happens has a potential leak - in case
of error neither run_helper() nor xterm_open() call free_stack().  At this
point passing a pointer is not needed - the stack pointer should be passed
directly, but this change is not done here.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: reenable compilation of enable_timer, disabled by mistake

2006-10-20T17:26:36+00:00

CONFIG_MODE_TT does not work there, the UML_ prefixed version must be used -
this causes a link-time failure when CONFIG_MODE_TT is enabled (i.e.  always
here, never by Jeff).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: code convention cleanup of a file

2006-10-20T17:26:36+00:00

Fix coding conventions violations is arch/um/os-Linux/helper.c.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: split memory allocation prototypes out of user.h

2006-10-20T17:26:36+00:00

user.h is too generic a header name.  I've split out allocation routines from
it.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: fix uname under setarch i386

2006-10-11T18:14:20+00:00

On a 64bit Uml, if run under "setarch i386" (which a user did), uname()
currently returns the obtained i686 as machine - fix that.  Btw, I'm quite
surprised that under setarch i386 a 64-bit binary can run.

Cc: Andi Kleen 
Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uml: make TT mode compile after setjmp-related changes

2006-10-11T18:14:20+00:00

Make TT mode compile after the introduction of klibc's implementation of
setjmp.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds