linux-kernel - [PATCH] drm/gma500: Replace kmap{,_atomic}() with page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230620180148.GA419134@sumitra.com>
Date:   Tue, 20 Jun 2023 11:01:48 -0700
From:   Sumitra Sharma <sumitraartsy@...il.com>
To:     Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Ira Weiny <ira.weiny@...el.com>, Fabio <fmdefrancesco@...il.com>,
        Deepak R Varma <drv@...lo.com>,
        Sumitra Sharma <sumitraartsy@...il.com>
Subject: [PATCH] drm/gma500: Replace kmap{,_atomic}() with page_address()

Remove unnecessary calls to kmap{,_atomic}() when acquiring
pages using GFP_DMA32.

The GFP_DMA32 uses the DMA32 zone to satisfy the allocation
requests. Therefore, pages allocated with GFP_DMA32 cannot
come from Highmem.

Avoid using calls to kmap_local_page() / kunmap_local() and
kmap() / kunmap() in the psb_mmu_alloc_pd function. Instead,
utilize page_address().

Remove the usage of kmap_atomic() / kunmap_atomic() in the
psb_mmu_alloc_pt function. Use page_address() instead.

Substitute kmap_atomic(pt->p) / kunmap_atomic(pt->v) calls
in the psb_mmu_pt_alloc_map_lock() and psb_mmu_pt_unmap_unlock()
functions with page_address(pt->p). This is possible as
pt = psb_mmu_alloc_pt(pd) allocates a page using
pt->p = alloc_page(GFP_DMA32).

Suggested-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Sumitra Sharma <sumitraartsy@...il.com>
---
 drivers/gpu/drm/gma500/mmu.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/gma500/mmu.c b/drivers/gpu/drm/gma500/mmu.c
index a70b01ccdf70..59aa5661e56a 100644
--- a/drivers/gpu/drm/gma500/mmu.c
+++ b/drivers/gpu/drm/gma500/mmu.c
@@ -184,20 +184,15 @@ struct psb_mmu_pd *psb_mmu_alloc_pd(struct psb_mmu_driver *driver,
 		pd->invalid_pte = 0;
 	}
 
-	v = kmap_local_page(pd->dummy_pt);
+	v = page_address(pd->dummy_pt);
 	for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i)
 		v[i] = pd->invalid_pte;
 
-	kunmap_local(v);
-
-	v = kmap_local_page(pd->p);
+	v = page_address(pd->p);
 	for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i)
 		v[i] = pd->invalid_pde;
 
-	kunmap_local(v);
-
-	clear_page(kmap(pd->dummy_page));
-	kunmap(pd->dummy_page);
+	clear_page(page_address(pd->dummy_page));
 
 	pd->tables = vmalloc_user(sizeof(struct psb_mmu_pt *) * 1024);
 	if (!pd->tables)
@@ -279,7 +274,7 @@ static struct psb_mmu_pt *psb_mmu_alloc_pt(struct psb_mmu_pd *pd)
 
 	spin_lock(lock);
 
-	v = kmap_atomic(pt->p);
+	v = page_address(pt->p);
 	clf = (uint8_t *) v;
 	ptes = (uint32_t *) v;
 	for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i)
@@ -293,7 +288,6 @@ static struct psb_mmu_pt *psb_mmu_alloc_pt(struct psb_mmu_pd *pd)
 		}
 		mb();
 	}
-	kunmap_atomic(v);
 	spin_unlock(lock);
 
 	pt->count = 0;
@@ -339,7 +333,7 @@ static struct psb_mmu_pt *psb_mmu_pt_alloc_map_lock(struct psb_mmu_pd *pd,
 			atomic_set(&pd->driver->needs_tlbflush, 1);
 		}
 	}
-	pt->v = kmap_atomic(pt->p);
+	pt->v = page_address(pt->p);
 	return pt;
 }
 
@@ -365,7 +359,6 @@ static void psb_mmu_pt_unmap_unlock(struct psb_mmu_pt *pt)
 	struct psb_mmu_pd *pd = pt->pd;
 	uint32_t *v;
 
-	kunmap_atomic(pt->v);
 	if (pt->count == 0) {
 		v = kmap_atomic(pd->p);
 		v[pt->index] = pd->invalid_pde;
-- 
2.25.1