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Introduce guest mem offset, static link example launcher

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In order to avoid problematic special linking of the Launcher, we give
the Host an offset: this means we can use any memory region in the
Launcher as Guest memory rather than insisting on mmap() at 0.

The result is quite pleasing: a number of casts are replaced with
simple additions.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2007-10-22 11:03:26 +10:00
parent 6649bb7af6
commit 3c6b5bfa3c
8 changed files with 162 additions and 139 deletions
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7
drivers/lguest/page_tables.c
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@@ -152,7 +152,7 @@ static unsigned long get_pfn(unsigned long virtpfn, int write)
static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
{
spte_t spte;
unsigned long pfn;
unsigned long pfn, base;
/* The Guest sets the global flag, because it thinks that it is using
* PGE. We only told it to use PGE so it would tell us whether it was
@@ -160,11 +160,14 @@ static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
* use the global bit, so throw it away. */
spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
/* The Guest's pages are offset inside the Launcher. */
base = (unsigned long)lg->mem_base / PAGE_SIZE;
/* We need a temporary "unsigned long" variable to hold the answer from
* get_pfn(), because it returns 0xFFFFFFFF on failure, which wouldn't
* fit in spte.pfn. get_pfn() finds the real physical number of the
* page, given the virtual number. */
pfn = get_pfn(gpte.pfn, write);
pfn = get_pfn(base + gpte.pfn, write);
if (pfn == -1UL) {
kill_guest(lg, "failed to get page %u", gpte.pfn);
/* When we destroy the Guest, we'll go through the shadow page