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authorRusty Russell <rusty@rustcorp.com.au>2007-10-22 11:03:26 +1000
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 15:49:50 +1000
commit3c6b5bfa3cf3b4057788e08482a468cc3bc00780 (patch)
treef0d67890f6f8c9d0840c9b19a483ec06cbf822ef /drivers/lguest/lguest_user.c
parent6649bb7af6a819b675bfcf22ab704737e905645a (diff)
Introduce guest mem offset, static link example launcher
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>
Diffstat (limited to 'drivers/lguest/lguest_user.c')
-rw-r--r--drivers/lguest/lguest_user.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 80d1b58c769..816d4d12a80 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -1,9 +1,9 @@
/*P:200 This contains all the /dev/lguest code, whereby the userspace launcher
* controls and communicates with the Guest. For example, the first write will
- * tell us the memory size, pagetable, entry point and kernel address offset.
- * A read will run the Guest until a signal is pending (-EINTR), or the Guest
- * does a DMA out to the Launcher. Writes are also used to get a DMA buffer
- * registered by the Guest and to send the Guest an interrupt. :*/
+ * tell us the Guest's memory layout, pagetable, entry point and kernel address
+ * offset. A read will run the Guest until something happens, such as a signal
+ * or the Guest doing a DMA out to the Launcher. Writes are also used to get a
+ * DMA buffer registered by the Guest and to send the Guest an interrupt. :*/
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
@@ -142,9 +142,11 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
return run_guest(lg, (unsigned long __user *)user);
}
-/*L:020 The initialization write supplies 4 32-bit values (in addition to the
+/*L:020 The initialization write supplies 5 32-bit values (in addition to the
* 32-bit LHREQ_INITIALIZE value). These are:
*
+ * base: The start of the Guest-physical memory inside the Launcher memory.
+ *
* pfnlimit: The highest (Guest-physical) page number the Guest should be
* allowed to access. The Launcher has to live in Guest memory, so it sets
* this to ensure the Guest can't reach it.
@@ -166,7 +168,7 @@ static int initialize(struct file *file, const u32 __user *input)
* Guest. */
struct lguest *lg;
int err, i;
- u32 args[4];
+ u32 args[5];
/* We grab the Big Lguest lock, which protects the global array
* "lguests" and multiple simultaneous initializations. */
@@ -194,8 +196,9 @@ static int initialize(struct file *file, const u32 __user *input)
/* Populate the easy fields of our "struct lguest" */
lg->guestid = i;
- lg->pfn_limit = args[0];
- lg->page_offset = args[3];
+ lg->mem_base = (void __user *)(long)args[0];
+ lg->pfn_limit = args[1];
+ lg->page_offset = args[4];
/* We need a complete page for the Guest registers: they are accessible
* to the Guest and we can only grant it access to whole pages. */
@@ -210,13 +213,13 @@ static int initialize(struct file *file, const u32 __user *input)
/* Initialize the Guest's shadow page tables, using the toplevel
* address the Launcher gave us. This allocates memory, so can
* fail. */
- err = init_guest_pagetable(lg, args[1]);
+ err = init_guest_pagetable(lg, args[2]);
if (err)
goto free_regs;
/* Now we initialize the Guest's registers, handing it the start
* address. */
- setup_regs(lg->regs, args[2]);
+ setup_regs(lg->regs, args[3]);
/* There are a couple of GDT entries the Guest expects when first
* booting. */