Re: [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value
From: Anshuman Khandual <hidden>
Date: 2020-09-01 03:15:58
Also in:
linux-arm-kernel, linux-mm, linux-s390, linuxppc-dev
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote:
quoted hunk ↗ jump to hunk
ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting that bit in random value. Signed-off-by: Aneesh Kumar K.V <redacted> --- mm/debug_vm_pgtable.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 086309fb9b6f..bbf9df0e64c6 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c@@ -44,10 +44,17 @@ * entry type. But these bits might affect the ability to clear entries with * pxx_clear() because of how dynamic page table folding works on s390. So * while loading up the entries do not change the lower 4 bits. It does not - * have affect any other platform. + * have affect any other platform. Also avoid the 62nd bit on ppc64 that is + * used to mark a pte entry. */ -#define S390_MASK_BITS 4 -#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS) +#define S390_SKIP_MASK GENMASK(3, 0) +#ifdef CONFIG_PPC_BOOK3S_64 +#define PPC64_SKIP_MASK GENMASK(62, 62) +#else +#define PPC64_SKIP_MASK 0x0 +#endif
Please drop the #ifdef CONFIG_PPC_BOOK3S_64 here. We already accommodate skip bits for a s390 platform requirement and can also do so for ppc64 as well. As mentioned before, please avoid adding any platform specific constructs in the test.
+#define ARCH_SKIP_MASK (S390_SKIP_MASK | PPC64_SKIP_MASK) +#define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) #define RANDOM_NZVALUE GENMASK(7, 0)
Please fix the alignments here. Feel free to consider following changes after this patch.
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 122416464e0f..f969031152bb 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c@@ -48,14 +48,11 @@ * have affect any other platform. Also avoid the 62nd bit on ppc64 that is * used to mark a pte entry. */ -#define S390_SKIP_MASK GENMASK(3, 0) -#ifdef CONFIG_PPC_BOOK3S_64 -#define PPC64_SKIP_MASK GENMASK(62, 62) -#else -#define PPC64_SKIP_MASK 0x0 -#endif -#define ARCH_SKIP_MASK (S390_SKIP_MASK | PPC64_SKIP_MASK) -#define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) +#define S390_SKIP_MASK GENMASK(3, 0) +#define PPC64_SKIP_MASK GENMASK(62, 62) +#define ARCH_SKIP_MASK (S390_SKIP_MASK | PPC64_SKIP_MASK) +#define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) + #define RANDOM_NZVALUE GENMASK(7, 0)
static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
Besides, there is also one checkpatch.pl warning here. WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line) #7: ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting that bit in total: 0 errors, 1 warnings, 20 lines checked