Differential D473 Diff 1782 sys/amd64/include/vmparam.h

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sys/amd64/include/vmparam.h

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	#define KERNBASE KVADDR(KPML4I, KPDPI, 0, 0)			#define KERNBASE KVADDR(KPML4I, KPDPI, 0, 0)

	#define UPT_MAX_ADDRESS KVADDR(PML4PML4I, PML4PML4I, PML4PML4I, PML4PML4I)			#define UPT_MAX_ADDRESS KVADDR(PML4PML4I, PML4PML4I, PML4PML4I, PML4PML4I)
	#define UPT_MIN_ADDRESS KVADDR(PML4PML4I, 0, 0, 0)			#define UPT_MIN_ADDRESS KVADDR(PML4PML4I, 0, 0, 0)

	#define VM_MAXUSER_ADDRESS UVADDR(NUPML4E, 0, 0, 0)			#define VM_MAXUSER_ADDRESS UVADDR(NUPML4E, 0, 0, 0)

	#define SHAREDPAGE (VM_MAXUSER_ADDRESS - PAGE_SIZE)			#define SHAREDPAGE (VM_MAXUSER_ADDRESS - PAGE_SIZE)
	#define USRSTACK SHAREDPAGE			#define USRSTACK (SHAREDPAGE - 4*PAGE_SIZE)
				opUnsubmitted Not Done Inline Actions Hi Robert! Show quoted text - The SHAREDPAGE - 4PAGE_SIZE constant is for separate the stack and the shared page, because the shared-page are double mapped with kernel and user-space, and the shared-page and stack are overlapped. This means, when stack become read-write-executable (in firefox case it's RWX), then the shared-page became too. To avoid this case, I separated it from stack with 4 page. op:* Hi Robert! - Show quoted text - The SHAREDPAGE - 4*PAGE_SIZE constant is for separate the stack…
				rwatsonUnsubmitted Not Done Inline Actions Please add a comment explaining the magic number '4', and ideally use a #define that makes the choice obvious as well. A bare number is almost never the right thing. rwatson: Please add a comment explaining the magic number '4', and ideally use a #define that makes the…

				rwatsonUnsubmitted Not Done Inline Actions Is the comment explaining (4) now elsewhere? I've not spotted it yet. rwatson: Is the comment explaining (4) now elsewhere? I've not spotted it yet.
	#define VM_MAX_ADDRESS UPT_MAX_ADDRESS			#define VM_MAX_ADDRESS UPT_MAX_ADDRESS
	#define VM_MIN_ADDRESS (0)			#define VM_MIN_ADDRESS (0)

	#define PHYS_TO_DMAP(x) ((x) \| DMAP_MIN_ADDRESS)			#define PHYS_TO_DMAP(x) ((x) \| DMAP_MIN_ADDRESS)
	#define DMAP_TO_PHYS(x) ((x) & ~DMAP_MIN_ADDRESS)			#define DMAP_TO_PHYS(x) ((x) & ~DMAP_MIN_ADDRESS)

	/*			/*
	* How many physical pages per kmem arena virtual page.			* How many physical pages per kmem arena virtual page.
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