On Thu, 05 Jun 2008 11:10:48 -0500 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Mon, 2008-06-02 at 15:57 +0900, FUJITA Tomonori wrote: > > Some REQ_TYPE_ATA_PC commands uses the stack buffers for DMA, which > > leads to memory corruption on a non-coherent platform. > > > > With regard to alignment and padding, ide-cd has the the dma safe > > check for sg requests and REQ_TYPE_ATA_PC. This adds the stack buffer > > check to that check. > > > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> > > Cc: Borislav Petkov <petkovbb@xxxxxxxxx> > > Cc: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> > > --- > > drivers/ide/ide-cd.c | 5 +++++ > > 1 files changed, 5 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c > > index e3f085c..e12d602 100644 > > --- a/drivers/ide/ide-cd.c > > +++ b/drivers/ide/ide-cd.c > > @@ -1195,6 +1195,7 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq) > > struct request_queue *q = drive->queue; > > unsigned int alignment; > > unsigned long addr; > > + unsigned long stack_mask = ~(THREAD_SIZE - 1); > > > > if (rq->bio) > > addr = (unsigned long)bio_data(rq->bio); > > @@ -1212,6 +1213,10 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq) > > alignment = queue_dma_alignment(q) | q->dma_pad_mask; > > if (addr & alignment || rq->data_len & alignment) > > info->dma = 0; > > + > > + if (!((addr & stack_mask) ^ > > + ((unsigned long)current->stack & stack_mask))) > > That can basically become > > if ((addr & stack_mask) == ((unsigned long)current->stack & stack_mask)) > > to be a bit clearer, can't it? Ok, I'll do next time. > I'm also not keen on the use of current->stack. It looks like this > commit: > > commit f7e4217b007d1f73e7e3cf10ba4fea4a608c603f > Author: Roman Zippel <zippel@xxxxxxxxxxxxxx> > Date: Wed May 9 02:35:17 2007 -0700 > > rename thread_info to stack > > Introduced a task_stack_page() accessor to get this instead, so perhaps > we should use it (I've cc'd Roman and linux-arch for opinions). Thanks. Seems that we should use it here (though current->stack look like work now). lib/debugobjects.c has the same code (that uses current->stack) to detect an address on the stack. Next time, I'll add a helper function to detect an address on the stack, which is useful for debugobjects.c, blk-map.c and ide-cd.c. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
