2006-12-06 10:00:46

by Hirokazu Takata

Subject: [PATCH 2.6.19] m32r: Fix access error handler to pass full 32-bit address

Don't mask the lower 12-bit of the page fault address.

In the current m32r kernel implementation, we use an access error handler
to detect page faults.
In order to check userspace address in do_page_fault, we have to pass
full 32-bit address to do_page_fault.

Signed-off-by: Hirokazu Takata <[email protected]>
---
arch/m32r/kernel/entry.S | 2 --
arch/m32r/mm/fault.c | 4 ++--
2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/m32r/kernel/entry.S b/arch/m32r/kernel/entry.S
index 5b01fd2..a2c472c 100644
--- a/arch/m32r/kernel/entry.S
+++ b/arch/m32r/kernel/entry.S
@@ -596,8 +596,6 @@ ENTRY(ace_handler)
beqz r1, inst
oprand:
ld r2, @(low(MDEVA_offset),r2) ; set address
- srli r2, #12
- slli r2, #12
srli r1, #1
bra 1f
inst:
diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index 8d5f551..9b9feb0 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -173,7 +173,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
-#if 0
+
if (error_code & ACE_USERMODE) {
/*
* accessing the stack below "spu" is always a bug.
@@ -184,7 +184,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
if (address + 4 < regs->spu)
goto bad_area;
}
-#endif
+
if (expand_stack(vma, address))
goto bad_area;
/*
--
1.4.4.1

--
Hirokazu Takata <[email protected]>
Linux/M32R Project: http://www.linux-m32r.org/

2006-12-06 11:03:21

by Hirokazu Takata

Subject: Re: [PATCH 2.6.19] m32r: Fix access error handler to pass full 32-bit address

Hi, Andrew,

Sorry, I sent a patch with wrong title.
On m32r, ACE is an acronym of not "access error", but "access exception".

Please drop the previous patch entitled "[PATCH 2.6.19] m32r: Fix access
error handler to pass full 32-bit address".
I will resend a correct patch again.

Thanks,

From: Hirokazu Takata <[email protected]>
Subject: [PATCH 2.6.19] m32r: Fix access error handler to pass full 32-bit address
Date: Wed, 06 Dec 2006 19:00:40 +0900
> Don't mask the lower 12-bit of the page fault address.
>
> In the current m32r kernel implementation, we use an access error handler
> to detect page faults.
> In order to check userspace address in do_page_fault, we have to pass
> full 32-bit address to do_page_fault.
>
> Signed-off-by: Hirokazu Takata <[email protected]>
> ---
> arch/m32r/kernel/entry.S | 2 --
> arch/m32r/mm/fault.c | 4 ++--
> 2 files changed, 2 insertions(+), 4 deletions(-)

-- Takata