On 2014/2/11 18:40, Ben Dooks wrote:

On 11/02/14 09:20, Jianguo Wu wrote:

quoted

When enable LPAE and big-endian in a hisilicon board, while specify
mem=384M mem=512M@7680M, will get bad page state:

Freeing unused kernel memory: 180K (c0466000 - c0493000)
BUG: Bad page state in process init  pfn:fa442
page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
page flags: 0x40000400(reserved)
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
[<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
[<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
[<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
[<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
[<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
[<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
[<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
[<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
[<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)

The bad pfn:fa442 is not system memory(mem=384M mem=512M@7680M), after debugging,
I find in page fault handler, will get wrong pfn from pte just after set pte,
as follow:
do_anonymous_page()
{
    ...
    set_pte_at(mm, address, page_table, entry);
    
    //debug code
    pfn = pte_pfn(entry);
    pr_info("pfn:0x%lx, pte:0x%llx\n", pfn, pte_val(entry));

    //read out the pte just set
    new_pte = pte_offset_map(pmd, address);
    new_pfn = pte_pfn(*new_pte);
    pr_info("new pfn:0x%lx, new pte:0x%llx\n", pfn, pte_val(entry));
    ...
}

Thanks, must have missed tickling this one.

quoted

pfn:   0x1fa4f5,     pte:0xc00001fa4f575f
new_pfn:0xfa4f5, new_pte:0xc00000fa4f5f5f    //new pfn/pte is wrong.

The bug is happened in cpu_v7_set_pte_ext(ptep, pte):
when pte is 64-bit, for little-endian, will store low 32-bit in r2,
high 32-bit in r3; for big-endian, will store low 32-bit in r3,
high 32-bit in r2, this will cause wrong pfn stored in pte,
so we should exchange r2 and r3 for big-endian.

Signed-off-by: Jianguo Wu <redacted>
---
  arch/arm/mm/proc-v7-3level.S |   10 ++++++++++
  1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index 6ba4bd9..71b3892 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S

@@ -65,6 +65,15 @@ ENDPROC(cpu_v7_switch_mm)
   */
  ENTRY(cpu_v7_set_pte_ext)
  #ifdef CONFIG_MMU
+#ifdef CONFIG_CPU_ENDIAN_BE8
+    tst    r3, #L_PTE_VALID
+    beq    1f
+    tst    r2, #1 << (57 - 32)        @ L_PTE_NONE
+    bicne    r3, #L_PTE_VALID
+    bne    1f
+    tst    r2, #1 << (55 - 32)        @ L_PTE_DIRTY
+    orreq    r3, #L_PTE_RDONLY
+#else
      tst    r2, #L_PTE_VALID
      beq    1f
      tst    r3, #1 << (57 - 32)        @ L_PTE_NONE

@@ -72,6 +81,7 @@ ENTRY(cpu_v7_set_pte_ext)
      bne    1f
      tst    r3, #1 << (55 - 32)        @ L_PTE_DIRTY
      orreq    r2, #L_PTE_RDONLY
+#endif
  1:    strd    r2, r3, [r0]
      ALT_SMP(W(nop))
      ALT_UP (mcr    p15, 0, r0, c7, c10, 1)        @ flush_pte
-- 1.7.1

If possible can we avoid large #ifdef blocks here?

Two ideas are

ARM_LE(tst r2, #L_PTE_VALID)
ARM_BE(tst r3, #L_PTE_VALID)

or change r2, r3 pair to say rlow, rhi and

#ifdef  CONFIG_CPU_ENDIAN_BE8
#define rlow r3
#define rhi r2
#else
#define rlow r2
#define rhi r3
#endif

Hi Ben,
Thanks for your suggestion, how about this?

Signed-off-by: Jianguo Wu <redacted>
---
 arch/arm/mm/proc-v7-3level.S |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index 01a719e..22e3ad6 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S

@@ -64,6 +64,14 @@ ENTRY(cpu_v7_switch_mm)
 	mov	pc, lr
 ENDPROC(cpu_v7_switch_mm)
 
+#ifdef __ARMEB__
+#define rl r3
+#define rh r2
+#else
+#define rl r2
+#define rh r3
+#endif
+
 /*
  * cpu_v7_set_pte_ext(ptep, pte)
  *

@@ -73,13 +81,13 @@ ENDPROC(cpu_v7_switch_mm)
  */
 ENTRY(cpu_v7_set_pte_ext)
 #ifdef CONFIG_MMU
-	tst	r2, #L_PTE_VALID
+	tst	rl, #L_PTE_VALID
 	beq	1f
-	tst	r3, #1 << (57 - 32)		@ L_PTE_NONE
-	bicne	r2, #L_PTE_VALID
+	tst	rh, #1 << (57 - 32)		@ L_PTE_NONE
+	bicne	rl, #L_PTE_VALID
 	bne	1f
-	tst	r3, #1 << (55 - 32)		@ L_PTE_DIRTY
-	orreq	r2, #L_PTE_RDONLY
+	tst	rh, #1 << (55 - 32)		@ L_PTE_DIRTY
+	orreq	rl, #L_PTE_RDONLY
 1:	strd	r2, r3, [r0]
 	ALT_SMP(W(nop))
 	ALT_UP (mcr	p15, 0, r0, c7, c10, 1)		@ flush_pte

-- 
1.7.1

Thanks,
Jianguo Wu

> 
> 



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