[PATCH 1/5] arm64: mm: Add slow_virt_to_phys()
From: Michael Kelley <hidden>
Date: 2018-06-19 21:25:00
Also in:
lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
Add slow_virt_to_phys() function for ARM64 that parallels the same function on x86/x64. This is needed by the architecture independent Hyper-V VMbus driver at drivers/hv/channel.c. The implementation directly translates the virtual address using the ARM64 'at' instruction. Signed-off-by: Michael Kelley <redacted> Reviewed-by: James Morris <redacted> --- arch/arm64/include/asm/memory.h | 6 ++++++ arch/arm64/mm/pageattr.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 49d9921..3f68dcf 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h@@ -265,6 +265,12 @@ static inline void *phys_to_virt(phys_addr_t x) } /* + * For memory where the underlying physical pages may not + * be contiguous. + */ +extern phys_addr_t slow_virt_to_phys(void *vaddr); + +/* * Drivers should NOT use these either. */ #define __pa(x) __virt_to_phys((unsigned long)(x))
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index a563593..8a42cac 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c@@ -19,6 +19,8 @@ #include <asm/pgtable.h> #include <asm/set_memory.h> #include <asm/tlbflush.h> +#include <asm/sysreg.h> +#include <asm/barrier.h> struct page_change_data { pgprot_t set_mask;
@@ -185,3 +187,38 @@ bool kernel_page_present(struct page *page) } #endif /* CONFIG_HIBERNATION */ #endif /* CONFIG_DEBUG_PAGEALLOC */ + +/* + * For virtual addresses where the underlyine physical memory may not be + * contiguous and the normal virt_to_phys gives the wrong result. This + * function does an actual translation using the 'at' instruction. + */ +phys_addr_t slow_virt_to_phys(void *virt_addr) +{ + phys_addr_t result; + unsigned long input = (unsigned long)virt_addr; + char touch; + int i; + + /* Try up to 3 times (an arbitrary number) */ + for (i = 0; i < 3; i++) { + /* Do the translation and check that it worked */ + asm volatile("at s1e1r, %0" : : "r" (input)); + isb(); + result = read_sysreg(par_el1); + if (likely(!(result & 0x1))) + return (result & GENMASK_ULL(51, 12)) | + (input & GENMASK_ULL(11, 0)); + /* + * Something failed. Read the page to fault in anything + * that isn't resident, then try again. "Anything" + * could include the page itself or hypervisor page tables. + */ + touch = READ_ONCE(*(char *)input); + dmb(sy); + } + + /* Let the caller sort it out. */ + return -1; +} +EXPORT_SYMBOL_GPL(slow_virt_to_phys);
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1.8.3.1