[PATCH v05 54/72] include/uapi/xen/privcmd.h: fix compilation in userspace
From: sstabellini@kernel.org (Stefano Stabellini)
Date: 2016-08-23 18:13:58
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lkml
On Tue, 23 Aug 2016, Russell King - ARM Linux wrote:
On Mon, Aug 22, 2016 at 08:33:11PM +0200, Mikko Rapeli wrote:quoted
xen/interface/xen.h is not exported from kernel headers so remove the dependency and provide needed defines for domid_t and xen_pfn_t if they are not already defined by some other e.g. Xen specific headers.I'm confused. How did we end up with a 64-bit PFN number on ARM? It's insane - especially as the kernel uses "unsigned long" almost everywhere for PFNs - we can't have physical addresses more than 44 bits (32 bit pfn + 4k page size).
That's because xen_pfn_t is the type used to store pfns in structures passed to Xen via hypercalls. The Xen hypercall ABI is shared between ARM and ARM64. On x86_32 and x86_64 we have different sizes for pfn types in the hypercall ABI and it caused quite a bit of trouble in the past as it is possible to run 32bit domains on a 64bit hypervisor. Having a common type for pfns on ARM and ARM64 helped a lot in that respect.
quoted
Suggested by Andrew Cooper [off-list ref] on lkml message [off-list ref]. The ifdef for ARM is ugly but did not find better solutions for it.#ifdef __arm__ maybe? Even if not, the unsightly parens are not necessary.
Yes, I think it should be: #if defined(__arm__) || defined(__aarch64__)
quoted hunk ↗ jump to hunk
diff --git a/arch/arm/include/asm/xen/interface.h b/arch/arm/include/asm/xen/interface.h index 75d5968..6898ee1 100644 --- a/arch/arm/include/asm/xen/interface.h +++ b/arch/arm/include/asm/xen/interface.h@@ -38,7 +38,7 @@ * fine since it simply wouldn't be able to create any sure pfns in * the first place. */ -typedef uint64_t xen_pfn_t; +typedef __u64 xen_pfn_t; #define PRI_xen_pfn "llx" typedef uint64_t xen_ulong_t; #define PRI_xen_ulong "llx"
Why this change?