Patchwork use correct initial region_offset

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Submitter Alex Rozenman
Date Jan. 27, 2011, 11:01 a.m.
Message ID <AANLkTin8RuJaSbvDNC2dNJVdwVYk8JqSCJTTY=jDh0y4@mail.gmail.com>
Download mbox | patch
Permalink /patch/80648/
State New
Headers show

Comments

Alex Rozenman - Jan. 27, 2011, 11:01 a.m.
Hi,

I found a bug in phys_page_find_alloc function causing initial region_offset
field to be set to incorrect initial value.
Usually, the pages are re-assigned afterwards, so the bug has very small
effect on regular QEMU users.
We use "memory unassigned" callback and this bug causes invalid addresses
there.

A small patch is attached. I have ssh membership on savannah. Please approve
and/or push.
This is my first time when I am suggesting patches to QEMU; I also would
like to add some fixes for
ppc440/ppc440x6 cores.
Aurelien Jarno - March 6, 2011, 5:48 p.m.
On Thu, Jan 27, 2011 at 01:01:01PM +0200, Alex Rozenman wrote:
> Hi,
> 
> I found a bug in phys_page_find_alloc function causing initial region_offset
> field to be set to incorrect initial value.
> Usually, the pages are re-assigned afterwards, so the bug has very small
> effect on regular QEMU users.
> We use "memory unassigned" callback and this bug causes invalid addresses
> there.
> 
> A small patch is attached. I have ssh membership on savannah. Please approve
> and/or push.
> This is my first time when I am suggesting patches to QEMU; I also would
> like to add some fixes for
> ppc440/ppc440x6 cores.
> 
> -- 
> Best regards,
> Alex Rozenman (rozenman@gmail.com).

> From 8935358ddf9bf5b80c8b8ac7014b650a519a3ebf Mon Sep 17 00:00:00 2001
> From: Alex Rozenman <rozenman@gmail.com>
> Date: Thu, 27 Jan 2011 12:47:57 +0200
> Subject: [PATCH] phys_page_find_alloc: use correct initial region_offset
> 
> ---
>  exec.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/exec.c b/exec.c
> index db9ff55..00667d7 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -416,6 +416,7 @@ static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
>      pd = *lp;
>      if (pd == NULL) {
>          int i;
> +        int first_index = index & ~(L2_SIZE - 1);
>  
>          if (!alloc) {
>              return NULL;
> @@ -425,7 +426,7 @@ static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
>  
>          for (i = 0; i < L2_SIZE; i++) {
>              pd[i].phys_offset = IO_MEM_UNASSIGNED;
> -            pd[i].region_offset = (index + i) << TARGET_PAGE_BITS;
> +            pd[i].region_offset = (first_index + i) << TARGET_PAGE_BITS;
>          }
>      }

The patch looks correct, but it is missing a Signed-off-by: entry. Also
please provide a description in the patch itself.

Patch

From 8935358ddf9bf5b80c8b8ac7014b650a519a3ebf Mon Sep 17 00:00:00 2001
From: Alex Rozenman <rozenman@gmail.com>
Date: Thu, 27 Jan 2011 12:47:57 +0200
Subject: [PATCH] phys_page_find_alloc: use correct initial region_offset

---
 exec.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/exec.c b/exec.c
index db9ff55..00667d7 100644
--- a/exec.c
+++ b/exec.c
@@ -416,6 +416,7 @@  static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
     pd = *lp;
     if (pd == NULL) {
         int i;
+        int first_index = index & ~(L2_SIZE - 1);
 
         if (!alloc) {
             return NULL;
@@ -425,7 +426,7 @@  static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
 
         for (i = 0; i < L2_SIZE; i++) {
             pd[i].phys_offset = IO_MEM_UNASSIGNED;
-            pd[i].region_offset = (index + i) << TARGET_PAGE_BITS;
+            pd[i].region_offset = (first_index + i) << TARGET_PAGE_BITS;
         }
     }
 
-- 
1.7.0.4