Re: [Crash-utility] [PATH v4 2/2] arm64: add 4-level translation
----- Original Message -----
On Tue, May 31, 2016 at 03:30:44PM -0400, Dave Anderson wrote:
>
> This patch looks good -- if it wasn't layered on top of the KASLR patch,
> I would check it into github.
This patch is almost independent from KASLR support, except that
adding new flags, VM_L4_4K and NEW_VMEMMAP, is conflicting.
When you merge it, please make a change.
-Takahiro AKASHI
OK, I see that now. But upon further inspection, I've got another question
about this piece:
+ * 4-levels / 4K pages
+ * 48-bit VA
+ */
+#define PTRS_PER_PGD_L4_4K ((1UL) << (48 - 39))
+#define PTRS_PER_PUD_L4_4K (512)
+#define PTRS_PER_PMD_L4_4K (512)
+#define PTRS_PER_PTE_L4_4K (512)
+#define PGDIR_SHIFT_L4_4K (39)
+#define PGDIR_SIZE_L4_4K ((1UL) << PGDIR_SHIFT_L4_4K)
+#define PGDIR_MASK_L4_4K (~(PGDIR_SIZE_L4_4K-1))
+#define PUD_SHIFT_L4_4K (30)
+#define PUD_SIZE_L4_4K ((1UL) << PUD_SHIFT_L4_4K)
+#define PUD_MASK_L4_4K (~(PUD_SIZE_L4_4K-1))
+#define PMD_SHIFT_L4_4K (21)
+#define PMD_SIZE_L4_4K (1UL << PMD_SHIFT_L4_4K)
+#define PMD_MASK_L4_4K (~(PMD_SIZE_L4_4K-1))
+
+#define PGDIR_SIZE (1UL << ((48 - 39) + 3))
+#define PGDIR_MASK (~(PGDIR_SIZE - 1))
+#define PGDIR_OFFSET(X) (((ulong)(X)) & (PGDIR_SIZE - 1))
+
You have defined PGDIR_SIZE_L4_4K and PGDIR_MASK_L4_4K, but they
are not used in arm64.c:
$ grep -e PGDIR_SIZE_L4_4K -e PGDIR_MASK_L4_4K arm64.c
$
Instead you define PGDIR_SIZE and PGDIR_MASK without the _L4_4K qualifiers,
and use them and PGDIR_OFFSET() in arm64.c.
Preferably convention should be followed such that the _L4_4K versions would
be used, but I see that PGDIR_SIZE_L4_4K is not equal to PGDIR_SIZE, and that
PGDIR_MASK_L4_4K is not equal to PGDIR_MASK. What's going on there?
Dave