Re: [PATCH 01/13] arm64: mm: Add p?d_large() definitions
From: Steven Price <steven.price@arm.com>
Date: 2019-02-18 14:11:50
Also in:
linux-mm, lkml
On 18/02/2019 11:29, Peter Zijlstra wrote:
On Fri, Feb 15, 2019 at 05:02:22PM +0000, Steven Price wrote:quoted
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index de70c1eabf33..09d308921625 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h@@ -428,6 +428,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, PMD_TYPE_TABLE) #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ PMD_TYPE_SECT) +#define pmd_large(x) pmd_sect(x) #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3 #define pud_sect(pud) (0)@@ -435,6 +436,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, #else #define pud_sect(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \ PUD_TYPE_SECT) +#define pud_large(x) pud_sect(x) #define pud_table(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \ PUD_TYPE_TABLE) #endifSo on x86 p*d_large() also matches p*d_huge() and thp, But it is not clear to me this p*d_sect() thing does so, given your definitions. See here why I care: http://lkml.kernel.org/r/20190201124741.GE31552@hirez.programming.kicks-ass.net
pmd_huge()/pud_huge() unfortunately are currently defined as '0' if !CONFIG_HUGETLB_PAGE and for this reason I was avoiding using them. While most code would reasonably not care about huge pages in that build configuration, the likes of the debugfs page table dump code needs to be able to recognise them in all build configurations. I believe the situation is the same on arm64 and x86. The other quirk is that higher levels are not supported for HUGETLB on some arch implementations. For example arm64 provides no definition for pgd_huge() so falls back to the generic defined as '0' implementation. The only architecture I can see that defines this is powerpc. Keeping this as '0' ensures that the otherwise dead code in other places is compiled out. Where p?d_huge is defined by the arch code the intention is that p?d_large(x)==p?d_huge(x). Thanks, Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel