Re: [PATCH] makedumpfile: arm64: Fix page table walk of 1GB section

2017-08-14 Thread Pratyush Anand 



On Monday 14 August 2017 02:07 PM, Atsushi Kumagai wrote:

Hello Bradley,

Sorry for my late reply, I'll merge this patch into v1.6.3.


Sorry, I missed it as well. Patch looks fine to me.However, I think /* 1GB  
Section*/ comment can be improved. Infact, other existing /* 1GB Section*/  
comment for PMD type is wrong.



Thanks for your work.

Regards,
Atsushi Kumagai


makedumpfile was generating large (> 500MB) vmcore files for an arm64
board with 2GB of DRAM.  It was not excluding any pages because the
mem_map address was not being converted correctly.

readmem: Can't convert a virtual address(ffc07fff6000) to physical
address.
readmem: type_addr: 0, addr:ffc07fff6000, size:16
section_mem_map_addr: Can't get a struct mem_section(ffc07fff6000).
mem_map (0)
mem_map : 0

makedumpfile was not handling 1GB sections in the PGD and was trying to
drill down to a PTE in which it was trying to dereference invalid
memory.  This patch adds code to check the PGD for a section type and
handle it instead of treating it as a table entry.

Signed-off-by: Bradley Bolen 
---
arch/arm64.c | 13 +
1 file changed, 13 insertions(+)

diff --git a/arch/arm64.c b/arch/arm64.c
index 958f57f..cae4b70 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -57,6 +57,8 @@ static unsigned long kimage_voffset;
#define PGDIR_SHIFT ((PAGESHIFT() - 3) * pgtable_level + 3)
#define PTRS_PER_PGD(1 << (va_bits - PGDIR_SHIFT))
#define PUD_SHIFT   get_pud_shift_arm64()
+#define PUD_SIZE   (1UL << PUD_SHIFT)
+#define PUD_MASK   (~(PUD_SIZE - 1))
#define PTRS_PER_PTE(1 << (PAGESHIFT() - 3))
#define PTRS_PER_PUDPTRS_PER_PTE
#define PMD_SHIFT   ((PAGESHIFT() - 3) * 2 + 3)
@@ -79,6 +81,10 @@ static unsigned long kimage_voffset;
#define PMD_TYPE_SECT   1
#define PMD_TYPE_TABLE  3

+#define PUD_TYPE_MASK  3
+#define PUD_TYPE_SECT  1
+#define PUD_TYPE_TABLE 3
+
#define pgd_index(vaddr)(((vaddr) >> PGDIR_SHIFT) & 
(PTRS_PER_PGD - 1))
#define pgd_offset(pgdir, vaddr)((pgd_t *)(pgdir) + pgd_index(vaddr))

@@ -253,6 +259,13 @@ vaddr_to_paddr_arm64(unsigned long vaddr)
return NOT_PADDR;
}

+   if ((pud_val(pudv) & PUD_TYPE_MASK) == PUD_TYPE_SECT) {
+   /* 1GB section */


May be we can write above comment like:
/* 1GB section for Page Table level = 4 and Page Size = 4KB*/

I think the other existing /* 1GB section */ comment for PMD_TYPE should be
/* 512MB section for Page Table level = 3 and Page Size = 64KB*/


+   paddr = (pud_val(pudv) & (PUD_MASK & PMD_SECTION_MASK))
+   + (vaddr & (PUD_SIZE - 1));
+   return paddr;
+   }
+
pmda = pmd_offset(puda, , vaddr);
if (!readmem(PADDR, (unsigned long long)pmda, , sizeof(pmdv))) {
ERRMSG("Can't read pmd\n");
--
1.9.3


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--
Regards
Pratyush

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RE: [PATCH] makedumpfile: arm64: Fix page table walk of 1GB section

2017-08-14 Thread Atsushi Kumagai 
Hello Bradley,

Sorry for my late reply, I'll merge this patch into v1.6.3.
Thanks for your work.

Regards,
Atsushi Kumagai

>makedumpfile was generating large (> 500MB) vmcore files for an arm64
>board with 2GB of DRAM.  It was not excluding any pages because the
>mem_map address was not being converted correctly.
>
>readmem: Can't convert a virtual address(ffc07fff6000) to physical
>address.
>readmem: type_addr: 0, addr:ffc07fff6000, size:16
>section_mem_map_addr: Can't get a struct mem_section(ffc07fff6000).
>mem_map (0)
>mem_map : 0
>
>makedumpfile was not handling 1GB sections in the PGD and was trying to
>drill down to a PTE in which it was trying to dereference invalid
>memory.  This patch adds code to check the PGD for a section type and
>handle it instead of treating it as a table entry.
>
>Signed-off-by: Bradley Bolen 
>---
> arch/arm64.c | 13 +
> 1 file changed, 13 insertions(+)
>
>diff --git a/arch/arm64.c b/arch/arm64.c
>index 958f57f..cae4b70 100644
>--- a/arch/arm64.c
>+++ b/arch/arm64.c
>@@ -57,6 +57,8 @@ static unsigned long kimage_voffset;
> #define PGDIR_SHIFT   ((PAGESHIFT() - 3) * pgtable_level + 3)
> #define PTRS_PER_PGD  (1 << (va_bits - PGDIR_SHIFT))
> #define PUD_SHIFT get_pud_shift_arm64()
>+#define PUD_SIZE  (1UL << PUD_SHIFT)
>+#define PUD_MASK  (~(PUD_SIZE - 1))
> #define PTRS_PER_PTE  (1 << (PAGESHIFT() - 3))
> #define PTRS_PER_PUD  PTRS_PER_PTE
> #define PMD_SHIFT ((PAGESHIFT() - 3) * 2 + 3)
>@@ -79,6 +81,10 @@ static unsigned long kimage_voffset;
> #define PMD_TYPE_SECT 1
> #define PMD_TYPE_TABLE3
>
>+#define PUD_TYPE_MASK 3
>+#define PUD_TYPE_SECT 1
>+#define PUD_TYPE_TABLE3
>+
> #define pgd_index(vaddr)  (((vaddr) >> PGDIR_SHIFT) & 
> (PTRS_PER_PGD - 1))
> #define pgd_offset(pgdir, vaddr)  ((pgd_t *)(pgdir) + pgd_index(vaddr))
>
>@@ -253,6 +259,13 @@ vaddr_to_paddr_arm64(unsigned long vaddr)
>   return NOT_PADDR;
>   }
>
>+  if ((pud_val(pudv) & PUD_TYPE_MASK) == PUD_TYPE_SECT) {
>+  /* 1GB section */
>+  paddr = (pud_val(pudv) & (PUD_MASK & PMD_SECTION_MASK))
>+  + (vaddr & (PUD_SIZE - 1));
>+  return paddr;
>+  }
>+
>   pmda = pmd_offset(puda, , vaddr);
>   if (!readmem(PADDR, (unsigned long long)pmda, , sizeof(pmdv))) {
>   ERRMSG("Can't read pmd\n");
>--
>1.9.3
>
>
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[PATCH] makedumpfile: arm64: Fix page table walk of 1GB section

2017-08-05 Thread Bradley Bolen 

Using an arm64 board, 2GB of memory, makedumpfile 1.6.2, and the v4.11 kernel,
I ran into an issue where the dumpfile was not excluding any pages thus
creating a huge vmcore.

I found that my board had a 1GB mapping in the PGD of 0xffc04000. This
isn't my area of expertise but I think I've pieced together how the kernel
handles page tables.

cat /proc/kallsyms |grep swapper_pg
ff8008a66000 B swapper_pg_dir

00a66800: 7fff9003 // pgd for virtual addr 0xffc0
00a66804: 
00a66808: 4711 // pgd for virtual addr 0xffc04000
00a6680c: 00e8

If I understand everything correctly then the pgd at 0xa66808 is a section and
not a pointer to a PMD, thus it should have been handled as a section instead
of trying to drill down to a PTE by the code in arch/arm64.c

Please find debug below and a proposed (probably not optimal) fix attached.

Thank you.

/usr/sbin/makedumpfile -F -c -d 31 --message-level=31 /proc/vmcore > /dev/null
sadump: unsupported architecture
LOAD (0)
phys_start : 8
phys_end : a58000
virt_start : ff800808
virt_end : ff8008a58000
LOAD (1)
phys_start : 0
phys_end : 600
virt_start : ffc0
virt_end : ffc00600
LOAD (2)
phys_start : 680
phys_end : 800
virt_start : ffc00680
virt_end : ffc00800
LOAD (3)
phys_start : a00
phys_end : 8000
virt_start : ffc00a00
virt_end : ffc08000
Linux kdump
page_size : 4096
phys_base : 0

max_mapnr : 8
There is enough free memory to be done in one cycle.

Buffer size for the cyclic mode: 131072
kimage_voffset : ff800800
max_physmem_bits : 30
section_size_bits: 1e
page_offset : ffc0

num of NODEs : 1

Memory type : SPARSEMEM_EX

readmem: Can't convert a virtual address(ffc07fff6000) to physical address.
readmem: type_addr: 0, addr:ffc07fff6000, size:16
section_mem_map_addr: Can't get a struct mem_section(ffc07fff6000).
mem_map (0)
mem_map : 0
pfn_start : 0
pfn_end : 4
readmem: Can't convert a virtual address(ffc07fff6010) to physical address.
readmem: type_addr: 0, addr:ffc07fff6010, size:16
section_mem_map_addr: Can't get a struct mem_section(ffc07fff6010).
mem_map (1)
mem_map : 0
pfn_start : 4
pfn_end : 8
mmap() is available on the kernel.
Checking for memory holes : [100.0 %] | STEP [Checking for memory holes ] :
0.017147 seconds
Excluding unnecessary pages : [100.0 %] \ STEP [Excluding unnecessary pages] :
0.34 seconds

Bradley Bolen (1):
  makedumpfile: arm64: Fix page table walk of 1GB section

 arch/arm64.c | 13 +
 1 file changed, 13 insertions(+)

-- 
1.9.3


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[PATCH] makedumpfile: arm64: Fix page table walk of 1GB section

2017-08-05 Thread Bradley Bolen 
makedumpfile was generating large (> 500MB) vmcore files for an arm64
board with 2GB of DRAM.  It was not excluding any pages because the
mem_map address was not being converted correctly.

readmem: Can't convert a virtual address(ffc07fff6000) to physical
address.
readmem: type_addr: 0, addr:ffc07fff6000, size:16
section_mem_map_addr: Can't get a struct mem_section(ffc07fff6000).
mem_map (0)
mem_map : 0

makedumpfile was not handling 1GB sections in the PGD and was trying to
drill down to a PTE in which it was trying to dereference invalid
memory.  This patch adds code to check the PGD for a section type and
handle it instead of treating it as a table entry.

Signed-off-by: Bradley Bolen 
---
 arch/arm64.c | 13 +
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64.c b/arch/arm64.c
index 958f57f..cae4b70 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -57,6 +57,8 @@ static unsigned long kimage_voffset;
 #define PGDIR_SHIFT((PAGESHIFT() - 3) * pgtable_level + 3)
 #define PTRS_PER_PGD   (1 << (va_bits - PGDIR_SHIFT))
 #define PUD_SHIFT  get_pud_shift_arm64()
+#define PUD_SIZE   (1UL << PUD_SHIFT)
+#define PUD_MASK   (~(PUD_SIZE - 1))
 #define PTRS_PER_PTE   (1 << (PAGESHIFT() - 3))
 #define PTRS_PER_PUD   PTRS_PER_PTE
 #define PMD_SHIFT  ((PAGESHIFT() - 3) * 2 + 3)
@@ -79,6 +81,10 @@ static unsigned long kimage_voffset;
 #define PMD_TYPE_SECT  1
 #define PMD_TYPE_TABLE 3
 
+#define PUD_TYPE_MASK  3
+#define PUD_TYPE_SECT  1
+#define PUD_TYPE_TABLE 3
+
 #define pgd_index(vaddr)   (((vaddr) >> PGDIR_SHIFT) & 
(PTRS_PER_PGD - 1))
 #define pgd_offset(pgdir, vaddr)   ((pgd_t *)(pgdir) + pgd_index(vaddr))
 
@@ -253,6 +259,13 @@ vaddr_to_paddr_arm64(unsigned long vaddr)
return NOT_PADDR;
}
 
+   if ((pud_val(pudv) & PUD_TYPE_MASK) == PUD_TYPE_SECT) {
+   /* 1GB section */
+   paddr = (pud_val(pudv) & (PUD_MASK & PMD_SECTION_MASK))
+   + (vaddr & (PUD_SIZE - 1));
+   return paddr;
+   }
+
pmda = pmd_offset(puda, , vaddr);
if (!readmem(PADDR, (unsigned long long)pmda, , sizeof(pmdv))) {
ERRMSG("Can't read pmd\n");
-- 
1.9.3


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