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Message-Id: <20170502162932.12578-1-tycho@docker.com>
Date: Tue, 2 May 2017 10:29:32 -0600
From: Tycho Andersen <tycho@...ker.com>
To: Tejun Heo <tj@...nel.org>,
Juerg Haefliger <juerg.haefliger@....com>
Cc: linux-ide@...r.kernel.org,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Tycho Andersen <tycho@...ker.com>
Subject: [PATCH] ata-sff: always map page before data transfer
The XPFO [1] patchset may unmap pages from physmap if they happened to be
destined for userspace. If such a page is unmapped, it needs to be
remapped. Rather than test if a page is in the highmem/xpfo unmapped state,
Christoph suggested [2] that we simply always map the page.
Suggested-by: Christoph Hellwig <hch@...radead.org>
Signed-off-by: Tycho Andersen <tycho@...ker.com>
CC: Juerg Haefliger <juerg.haefliger@....com>
CC: Tejun Heo <tj@...nel.org>
[1]: https://lkml.org/lkml/2016/11/4/245
[2]: https://lkml.org/lkml/2016/11/4/253
---
I don't understand all the factors at play here, so thoughts are definitely
welcome.
---
drivers/ata/libata-sff.c | 50 +++++++++++++++++-------------------------------
1 file changed, 18 insertions(+), 32 deletions(-)
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 2bd92dc..8da2572 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -703,6 +703,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
struct page *page;
unsigned int offset;
unsigned char *buf;
+ unsigned long flags;
if (qc->curbytes == qc->nbytes - qc->sect_size)
ap->hsm_task_state = HSM_ST_LAST;
@@ -716,24 +717,16 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
- if (PageHighMem(page)) {
- unsigned long flags;
-
- /* FIXME: use a bounce buffer */
- local_irq_save(flags);
- buf = kmap_atomic(page);
+ /* FIXME: use a bounce buffer */
+ local_irq_save(flags);
+ buf = kmap_atomic(page);
- /* do the actual data transfer */
- ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size,
- do_write);
+ /* do the actual data transfer */
+ ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size,
+ do_write);
- kunmap_atomic(buf);
- local_irq_restore(flags);
- } else {
- buf = page_address(page);
- ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size,
- do_write);
- }
+ kunmap_atomic(buf);
+ local_irq_restore(flags);
if (!do_write && !PageSlab(page))
flush_dcache_page(page);
@@ -836,6 +829,7 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
struct page *page;
unsigned char *buf;
unsigned int offset, count, consumed;
+ unsigned long flags;
next_sg:
sg = qc->cursg;
@@ -861,24 +855,16 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
- if (PageHighMem(page)) {
- unsigned long flags;
-
- /* FIXME: use bounce buffer */
- local_irq_save(flags);
- buf = kmap_atomic(page);
+ /* FIXME: use bounce buffer */
+ local_irq_save(flags);
+ buf = kmap_atomic(page);
- /* do the actual data transfer */
- consumed = ap->ops->sff_data_xfer(qc, buf + offset,
- count, rw);
+ /* do the actual data transfer */
+ consumed = ap->ops->sff_data_xfer(qc, buf + offset,
+ count, rw);
- kunmap_atomic(buf);
- local_irq_restore(flags);
- } else {
- buf = page_address(page);
- consumed = ap->ops->sff_data_xfer(qc, buf + offset,
- count, rw);
- }
+ kunmap_atomic(buf);
+ local_irq_restore(flags);
bytes -= min(bytes, consumed);
qc->curbytes += count;
--
2.9.3
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