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sys/amd64/include/vmparam.h

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#define VM_MIN_KERNEL_ADDRESS KVADDR(KPML4BASE, 0, 0, 0) #define VM_MIN_KERNEL_ADDRESS KVADDR(KPML4BASE, 0, 0, 0)
#define VM_MAX_KERNEL_ADDRESS KVADDR(KPML4BASE + NKPML4E - 1, \ #define VM_MAX_KERNEL_ADDRESS KVADDR(KPML4BASE + NKPML4E - 1, \
NPDPEPG-1, NPDEPG-1, NPTEPG-1) NPDPEPG-1, NPDEPG-1, NPTEPG-1)
#define DMAP_MIN_ADDRESS KVADDR(DMPML4I, 0, 0, 0) #define DMAP_MIN_ADDRESS KVADDR(DMPML4I, 0, 0, 0)
#define DMAP_MAX_ADDRESS KVADDR(DMPML4I + NDMPML4E, 0, 0, 0) #define DMAP_MAX_ADDRESS KVADDR(DMPML4I + NDMPML4E, 0, 0, 0)
#define KERNBASE KVADDR(KPML4I, KPDPI, 0, 0) #define KERNBASE KVADDR(KPML4I, KPDPI, 0, 0)
opUnsubmitted
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Hi Robert!

  • Show quoted text -

The SHAREDPAGE - 4*PAGE_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…
#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 SHAREDPAGE_GUARD (4 * PAGE_SIZE)
#define USRSTACK (SHAREDPAGE - SHAREDPAGE_GUARD)
rwatsonUnsubmitted
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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
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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)
/* /*
* XXX Allowing dmaplimit == 0 is a temporary workaround for vt(4) efifb's * XXX Allowing dmaplimit == 0 is a temporary workaround for vt(4) efifb's
* early use of PHYS_TO_DMAP before the mapping is actually setup. This works * early use of PHYS_TO_DMAP before the mapping is actually setup. This works
* because the result is not actually accessed until later, but the early * because the result is not actually accessed until later, but the early
* vt fb startup needs to be reworked. * vt fb startup needs to be reworked.
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