Messages in this thread | | | Date | Wed, 24 Mar 2010 00:57:46 -0400 (EDT) | From | Oren Laadan <> | Subject | Re: [C/R ARM][PATCH 1/3] ARM: Rudimentary syscall interfaces |
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On Tue, 23 Mar 2010, Matt Helsley wrote:
> On Tue, Mar 23, 2010 at 08:53:42PM +0000, Russell King - ARM Linux wrote: > > On Sun, Mar 21, 2010 at 09:06:03PM -0400, Christoffer Dall wrote: > > > This small commit introduces a global state of system calls for ARM > > > making it possible for a debugger or checkpointing to gain information > > > about another process' state with respect to system calls. > > > > I don't particularly like the idea that we always store the syscall > > number to memory for every system call, whether the stored version is > > used or not. > > > > Since ARM caches are generally not write allocate, this means mostly > > write-only variables can have a higher than expected expense. > > > > Is there not some thread flag which can be checked to see if we need to > > store the syscall number? > > Perhaps before we freeze the task we can save the syscall number on ARM. > The patches suggest that the signal delivery path -- which the freezer > utilizes -- has the syscall number already. > > Should work since the threads must be frozen first anyway.
I like the idea.
However, would it also work for those cases when the freezing does not occur from the signal delivery path - e.g. for vfork and ptraced tasks ?
Oren.
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