Re: Crash on FSL Book3E due to pte_pgprot()? (was Re: [PATCH v3 12/24] powerpc/mm: use pte helpers in generic code)

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2018-10-17 10:32:20
Also in: dri-devel, linux-arm-kernel, linux-block, linux-fbdev, lkml
Reply to: Christophe Leroy, 2018-10-17

Christophe Leroy [off-list ref] writes:

On 10/17/2018 12:59 AM, Michael Ellerman wrote:

...

quoted

The question is what's the right way to fix it? Should pte_pgprot() not
be filtering those bits out on book3e?

I think we should not use pte_pggrot() for that then. What about the 
below fix ?

Thanks, that almost works.

pte_mkprivileged() also needs to not strip _PAGE_BAP_SR.


But there's also a use of pte_pgprot() in mm/memory.c, and I think that
is also broken now that we don't add PAGE_KERNEL back in.

Aneesh is going to do a patch to make pte_pgprot() only mask the PFN
which is what other arches do.

cheers

quoted hunk ↗ jump to hunk

From: Christophe Leroy <redacted>
Date: Wed, 17 Oct 2018 05:56:25 +0000
Subject: [PATCH] powerpc/mm: don't use pte_pgprot() in ioremap_prot()

pte_pgprot() filters out some required flags like _PAGE_PRESENT.

This patch replaces pte_pgprot() by __pgprot(pte_val())
in ioremap_prot()

Fixes: 26973fa5ac0e ("powerpc/mm: use pte helpers in generic code")
Signed-off-by: Christophe Leroy <redacted>
---
  arch/powerpc/mm/pgtable_32.c | 3 ++-
  arch/powerpc/mm/pgtable_64.c | 4 ++--
  2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 5877f5aa8f5d..a606e2f4937b 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c

@@ -122,7 +122,8 @@ ioremap_prot(phys_addr_t addr, unsigned long size,

unsigned long flags)
  	pte = pte_exprotect(pte);
  	pte = pte_mkprivileged(pte);

-	return __ioremap_caller(addr, size, pte_pgprot(pte), 
__builtin_return_address(0));
+	return __ioremap_caller(addr, size, __pgprot(pte_val(pte)),
+				__builtin_return_address(0));
  }
  EXPORT_SYMBOL(ioremap_prot);

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index fb1375c07e8c..836bf436cabb 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c

@@ -245,8 +245,8 @@ void __iomem * ioremap_prot(phys_addr_t addr,

unsigned long size,
  	pte = pte_mkprivileged(pte);

  	if (ppc_md.ioremap)
-		return ppc_md.ioremap(addr, size, pte_pgprot(pte), caller);
-	return __ioremap_caller(addr, size, pte_pgprot(pte), caller);
+		return ppc_md.ioremap(addr, size, __pgprot(pte_val(pte)), caller);
+	return __ioremap_caller(addr, size, __pgprot(pte_val(pte)), caller);
  }


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