Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com --- arch/arm64/include/asm/pgtable-prot.h | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 9a21b84536f2..8dc6c5cdabe6 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -32,11 +32,11 @@ #define PROT_DEFAULT (_PROT_DEFAULT | PTE_MAYBE_NG) #define PROT_SECT_DEFAULT (_PROT_SECT_DEFAULT | PMD_MAYBE_NG)
-#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) -#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) -#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) -#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) -#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL)) +#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) +#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) +#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) +#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) +#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL))
#define PROT_SECT_DEVICE_nGnRE (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE)) #define PROT_SECT_NORMAL (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL)) @@ -80,8 +80,9 @@ #define PAGE_S2_DEVICE __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_S2_XN)
#define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN) -#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE) -#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_WRITE) +/* shared+writable pages are clean by default, hence PTE_RDONLY|PTE_WRITE */ +#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE) +#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_WRITE) #define PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN) #define PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN) #define PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_RDONLY | PTE_NG | PTE_PXN)
On Tue, Oct 29, 2019 at 03:30:51PM +0000, Catalin Marinas wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
arch/arm64/include/asm/pgtable-prot.h | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 9a21b84536f2..8dc6c5cdabe6 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -32,11 +32,11 @@ #define PROT_DEFAULT (_PROT_DEFAULT | PTE_MAYBE_NG) #define PROT_SECT_DEFAULT (_PROT_SECT_DEFAULT | PMD_MAYBE_NG) -#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) -#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) -#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) -#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) -#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL)) +#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) +#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) +#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) +#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) +#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL)) #define PROT_SECT_DEVICE_nGnRE (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE)) #define PROT_SECT_NORMAL (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL)) @@ -80,8 +80,9 @@ #define PAGE_S2_DEVICE __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_S2_XN) #define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN) -#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE) -#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_WRITE) +/* shared+writable pages are clean by default, hence PTE_RDONLY|PTE_WRITE */ +#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE) +#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_WRITE) #define PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN) #define PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN) #define PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_RDONLY | PTE_NG | PTE_PXN)
Looks correct to me, and I don't think ptep_set_access_flags() breaks. I've queued it as a fix.
Will
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
Hey, So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine). Its odd, because the system does boot and is alive, but seems to stall out at the boot animation, and userland never finishes coming up to the home screen. It just sits there without a useful error message that I can find so far. Reverting just this patch seems to solve it and it boots all the way.
I'll try to dig further to see what might be going on (the mali driver is a prime suspect here), but I wanted to raise the flag since we're at the end of the -rc cycle.
thanks -john
Hi John,
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
Hey, So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine).
Hmm. Annoying this wasn't spotted by CI.
Its odd, because the system does boot and is alive, but seems to stall out at the boot animation, and userland never finishes coming up to the home screen. It just sits there without a useful error message that I can find so far. Reverting just this patch seems to solve it and it boots all the way.
Given that I don't think the HiKey960 supports h/w DBM, my initial guess is that the GPU is stuck on a page fault.
I'll try to dig further to see what might be going on (the mali driver is a prime suspect here), but I wanted to raise the flag since we're at the end of the -rc cycle.
What exactly are you using for the mali driver?
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
Thanks,
Will
--->8
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 8dc6c5cdabe6..17a8eb13f4ce 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -32,11 +32,11 @@ #define PROT_DEFAULT (_PROT_DEFAULT | PTE_MAYBE_NG) #define PROT_SECT_DEFAULT (_PROT_SECT_DEFAULT | PMD_MAYBE_NG)
-#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) -#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) -#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) -#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) -#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL)) +#define PROT_DEVICE_nGnRnE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE)) +#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE)) +#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_NC)) +#define PROT_NORMAL_WT (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL_WT)) +#define PROT_NORMAL (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_ATTRINDX(MT_NORMAL))
#define PROT_SECT_DEVICE_nGnRE (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE)) #define PROT_SECT_NORMAL (PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL))
On Tue, Nov 05, 2019 at 10:29:03AM +0000, Will Deacon wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
[...]
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
Another thing worth trying is reverting commit 747a70e60b72 ("arm64: Fix copy-on-write referencing in HugeTLB") when this patch is applied. That commit is not just about hugetlb but changes pte_same() to ignore PTE_RDONLY on the assumption that this is set by set_pte_at(). We subsequently changed set_pte_at() to drop PTE_RDONLY.
On Tue, Nov 5, 2019 at 8:54 AM Catalin Marinas catalin.marinas@arm.com wrote:
On Tue, Nov 05, 2019 at 10:29:03AM +0000, Will Deacon wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
[...]
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
Another thing worth trying is reverting commit 747a70e60b72 ("arm64: Fix copy-on-write referencing in HugeTLB") when this patch is applied. That commit is not just about hugetlb but changes pte_same() to ignore PTE_RDONLY on the assumption that this is set by set_pte_at(). We subsequently changed set_pte_at() to drop PTE_RDONLY.
Just to confirm, reverting 747a70e60b72 instead of aa57157be69f also seems to avoid the issue I'm seeing.
I've not tried Will patch but I'll do that next. Though its not clear if you wanted me to revert 747a70e60b72 on top of Will's test patch or not?
thanks -john
On Tue, Nov 5, 2019 at 1:17 PM John Stultz john.stultz@linaro.org wrote:
On Tue, Nov 5, 2019 at 8:54 AM Catalin Marinas catalin.marinas@arm.com wrote:
On Tue, Nov 05, 2019 at 10:29:03AM +0000, Will Deacon wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
[...]
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
Another thing worth trying is reverting commit 747a70e60b72 ("arm64: Fix copy-on-write referencing in HugeTLB") when this patch is applied. That commit is not just about hugetlb but changes pte_same() to ignore PTE_RDONLY on the assumption that this is set by set_pte_at(). We subsequently changed set_pte_at() to drop PTE_RDONLY.
Just to confirm, reverting 747a70e60b72 instead of aa57157be69f also seems to avoid the issue I'm seeing.
I've not tried Will patch but I'll do that next. Though its not clear if you wanted me to revert 747a70e60b72 on top of Will's test patch or not?
Not sure if its useful data, but while Will's patch on its own didn't change the behavior, it along with reverting 747a70e60b72 seems to work the same as just reverting 747a70e60b72 alone.
thanks -john
On Tue, Nov 05, 2019 at 01:17:11PM -0800, John Stultz wrote:
On Tue, Nov 5, 2019 at 8:54 AM Catalin Marinas catalin.marinas@arm.com wrote:
On Tue, Nov 05, 2019 at 10:29:03AM +0000, Will Deacon wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
[...]
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
Another thing worth trying is reverting commit 747a70e60b72 ("arm64: Fix copy-on-write referencing in HugeTLB") when this patch is applied. That commit is not just about hugetlb but changes pte_same() to ignore PTE_RDONLY on the assumption that this is set by set_pte_at(). We subsequently changed set_pte_at() to drop PTE_RDONLY.
Just to confirm, reverting 747a70e60b72 instead of aa57157be69f also seems to avoid the issue I'm seeing.
Thanks for confirming. I'm not sure about all the interactions in your kernel but just looking at commit 747a70e60b72 it likely needs to be reverted anyway. I'll send a separate patch and hopefully Steve can confirm that it doesn't break the original hugetlb use-case.
On Tue, Nov 5, 2019 at 2:29 AM Will Deacon will@kernel.org wrote:
Hi John,
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
Hey, So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine).
Hmm. Annoying this wasn't spotted by CI.
Its odd, because the system does boot and is alive, but seems to stall out at the boot animation, and userland never finishes coming up to the home screen. It just sits there without a useful error message that I can find so far. Reverting just this patch seems to solve it and it boots all the way.
Given that I don't think the HiKey960 supports h/w DBM, my initial guess is that the GPU is stuck on a page fault.
I'll try to dig further to see what might be going on (the mali driver is a prime suspect here), but I wanted to raise the flag since we're at the end of the -rc cycle.
What exactly are you using for the mali driver?
I've got an old r10p0 bifrost blob we were given and kernel patches I've carried forward since then.
Again, I don't want to distract you too much for something that may be related to a blob driver. I mostly just wanted to raise a flag in case there was something off that might affect others.
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
I'll give this a try! Feel free to let me know if there's anything else I should test.
thanks -john
On Tue, Nov 05, 2019 at 09:06:43AM -0800, John Stultz wrote:
On Tue, Nov 5, 2019 at 2:29 AM Will Deacon will@kernel.org wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine).
[...]
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
I'll give this a try! Feel free to let me know if there's anything else I should test.
Thanks. Also worth trying to revert 747a70e60b72 instead of this patch, as Catalin suggested.
Will
On Tue, Nov 5, 2019 at 9:06 AM John Stultz john.stultz@linaro.org wrote:
On Tue, Nov 5, 2019 at 2:29 AM Will Deacon will@kernel.org wrote:
Hi John,
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
Hey, So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine).
Hmm. Annoying this wasn't spotted by CI.
Its odd, because the system does boot and is alive, but seems to stall out at the boot animation, and userland never finishes coming up to the home screen. It just sits there without a useful error message that I can find so far. Reverting just this patch seems to solve it and it boots all the way.
Given that I don't think the HiKey960 supports h/w DBM, my initial guess is that the GPU is stuck on a page fault.
I'll try to dig further to see what might be going on (the mali driver is a prime suspect here), but I wanted to raise the flag since we're at the end of the -rc cycle.
What exactly are you using for the mali driver?
I've got an old r10p0 bifrost blob we were given and kernel patches I've carried forward since then.
Again, I don't want to distract you too much for something that may be related to a blob driver. I mostly just wanted to raise a flag in case there was something off that might affect others.
Just as a further detail (about to close up for the day), I'm also seeing this issue on the HiKey board as well. Similarly reverting 747a70e60b72 resolves it. Its a mali blob driver too, but a different one (utgard) which makes me suspect this might be a real issue w/ something in AOSP.
I'll be testing on a db845c tomorrow morning to see if I can trigger it there as well.
thanks -john
On Tue, Nov 5, 2019 at 2:29 AM Will Deacon will@kernel.org wrote:
On Mon, Nov 04, 2019 at 05:16:42PM -0800, John Stultz wrote:
On Tue, Oct 29, 2019 at 8:31 AM Catalin Marinas catalin.marinas@arm.com wrote:
Shared and writable mappings (__S.1.) should be clean (!dirty) initially and made dirty on a subsequent write either through the hardware DBM (dirty bit management) mechanism or through a write page fault. A clean pte for the arm64 kernel is one that has PTE_RDONLY set and PTE_DIRTY clear.
The PAGE_SHARED{,_EXEC} attributes have PTE_WRITE set (PTE_DBM) and PTE_DIRTY clear. Prior to commit 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()"), it was the responsibility of set_pte_at() to set the PTE_RDONLY bit and mark the pte clean if the software PTE_DIRTY bit was not set. However, the above commit removed the pte_sw_dirty() check and the subsequent setting of PTE_RDONLY in set_pte_at() while leaving the PAGE_SHARED{,_EXEC} definitions unchanged. The result is that shared+writable mappings are now dirty by default
Fix the above by explicitly setting PTE_RDONLY in PAGE_SHARED{,_EXEC}. In addition, remove the superfluous PTE_DIRTY bit from the kernel PROT_* attributes.
Fixes: 73e86cb03cf2 ("arm64: Move PTE_RDONLY bit handling out of set_pte_at()") Cc: stable@vger.kernel.org # 4.14.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
Hey, So I'm not yet sure why, but I've just validated that this patch is causing trouble with booting AOSP on HiKey960 with 5.4-rc6 (-rc5 works fine).
Hmm. Annoying this wasn't spotted by CI.
Its odd, because the system does boot and is alive, but seems to stall out at the boot animation, and userland never finishes coming up to the home screen. It just sits there without a useful error message that I can find so far. Reverting just this patch seems to solve it and it boots all the way.
Given that I don't think the HiKey960 supports h/w DBM, my initial guess is that the GPU is stuck on a page fault.
I'll try to dig further to see what might be going on (the mali driver is a prime suspect here), but I wanted to raise the flag since we're at the end of the -rc cycle.
What exactly are you using for the mali driver?
As an experiment, can you try reverting just the part of the patch that removes PTE_DIRTY from the PROT_* definitions? (see below)
So reverting just the bit you sent here re-adding the PTE_DIRTY bit didn't seem to fix it. I still see things stalling at the boot animation.
thanks -john
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Catalin Marinas -
John Stultz -
Will Deacon