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generalize lgread_u32/lgwrite_u32.

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Jes complains that page table code still uses lgread_u32 even though
it now uses general kernel pte types.  The best thing to do is to
generalize lgread_u32 and lgwrite_u32.

This means we lose the efficiency of getuser().  We could potentially
regain it if we used __copy_from_user instead of copy_from_user, but
I'm not certain that our range check is equivalent to access_ok() on
all platforms.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Jes Sorensen <jes@sgi.com>
This commit is contained in:
Rusty Russell
2007-10-22 11:24:24 +10:00
parent 56ae43dfe2
commit 2d37f94a28
7 changed files with 38 additions and 46 deletions
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39
drivers/lguest/core.c
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@@ -145,33 +145,10 @@ int lguest_address_ok(const struct lguest *lg,
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
/* This is a convenient routine to get a 32-bit value from the Guest (a very
* common operation). Here we can see how useful the kill_lguest() routine we
* met in the Launcher can be: we return a random value (0) instead of needing
* to return an error. */
u32 lgread_u32(struct lguest *lg, unsigned long addr)
{
u32 val = 0;
/* Don't let them access lguest binary. */
if (!lguest_address_ok(lg, addr, sizeof(val))
|| get_user(val, (u32 *)(lg->mem_base + addr)) != 0)
kill_guest(lg, "bad read address %#lx: pfn_limit=%u membase=%p", addr, lg->pfn_limit, lg->mem_base);
return val;
}
/* Same thing for writing a value. */
void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val)
{
if (!lguest_address_ok(lg, addr, sizeof(val))
|| put_user(val, (u32 *)(lg->mem_base + addr)) != 0)
kill_guest(lg, "bad write address %#lx", addr);
}
/* This routine is more generic, and copies a range of Guest bytes into a
* buffer. If the copy_from_user() fails, we fill the buffer with zeroes, so
* the caller doesn't end up using uninitialized kernel memory. */
void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
/* This routine copies memory from the Guest. Here we can see how useful the
* kill_lguest() routine we met in the Launcher can be: we return a random
* value (all zeroes) instead of needing to return an error. */
void __lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_from_user(b, lg->mem_base + addr, bytes) != 0) {
@@ -181,15 +158,15 @@ void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
}
}
/* Similarly, our generic routine to copy into a range of Guest bytes. */
void lgwrite(struct lguest *lg, unsigned long addr, const void *b,
unsigned bytes)
/* This is the write (copy into guest) version. */
void __lgwrite(struct lguest *lg, unsigned long addr, const void *b,
unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_to_user(lg->mem_base + addr, b, bytes) != 0)
kill_guest(lg, "bad write address %#lx len %u", addr, bytes);
}
/* (end of memory access helper routines) :*/
/*:*/
/*H:030 Let's jump straight to the the main loop which runs the Guest.
* Remember, this is called by the Launcher reading /dev/lguest, and we keep