Commit 2d37f94a authored by Rusty Russell's avatar Rusty Russell

generalize lgread_u32/lgwrite_u32.

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: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarJes Sorensen <jes@sgi.com>
parent 56ae43df
......@@ -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,
/* 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
......
......@@ -47,7 +47,7 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
char msg[128];
/* If the lgread fails, it will call kill_guest() itself; the
* kill_guest() with the message will be ignored. */
lgread(lg, msg, args->arg1, sizeof(msg));
__lgread(lg, msg, args->arg1, sizeof(msg));
msg[sizeof(msg)-1] = '\0';
kill_guest(lg, "CRASH: %s", msg);
break;
......
......@@ -45,7 +45,7 @@ static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
{
/* Stack grows upwards: move stack then write value. */
*gstack -= 4;
lgwrite_u32(lg, *gstack, val);
lgwrite(lg, *gstack, u32, val);
}
/*H:210 The set_guest_interrupt() routine actually delivers the interrupt or
......
......@@ -98,12 +98,27 @@ struct lguest
extern struct mutex lguest_lock;
/* core.c: */
u32 lgread_u32(struct lguest *lg, unsigned long addr);
void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val);
void lgread(struct lguest *lg, void *buf, unsigned long addr, unsigned len);
void lgwrite(struct lguest *lg, unsigned long, const void *buf, unsigned len);
int lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len);
void __lgread(struct lguest *, void *, unsigned long, unsigned);
void __lgwrite(struct lguest *, unsigned long, const void *, unsigned);
/*L:306 Using memory-copy operations like that is usually inconvient, so we
* have the following helper macros which read and write a specific type (often
* an unsigned long).
*
* This reads into a variable of the given type then returns that. */
#define lgread(lg, addr, type) \
({ type _v; __lgread((lg), &_v, (addr), sizeof(_v)); _v; })
/* This checks that the variable is of the given type, then writes it out. */
#define lgwrite(lg, addr, type, val) \
do { \
typecheck(type, val); \
__lgwrite((lg), (addr), &(val), sizeof(val)); \
} while(0)
/* (end of memory access helper routines) :*/
int run_guest(struct lguest *lg, unsigned long __user *user);
/* Helper macros to obtain the first 12 or the last 20 bits, this is only the
......
......@@ -209,7 +209,7 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
pte_t *spte;
/* First step: get the top-level Guest page table entry. */
gpgd = __pgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
return 0;
......@@ -235,7 +235,7 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
/* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later. */
gpte_ptr = gpte_addr(lg, gpgd, vaddr);
gpte = __pte(lgread_u32(lg, gpte_ptr));
gpte = lgread(lg, gpte_ptr, pte_t);
/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
......@@ -278,7 +278,7 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
/* Finally, we write the Guest PTE entry back: we've set the
* _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags. */
lgwrite_u32(lg, gpte_ptr, pte_val(gpte));
lgwrite(lg, gpte_ptr, pte_t, gpte);
/* We succeeded in mapping the page! */
return 1;
......@@ -366,12 +366,12 @@ unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
pte_t gpte;
/* First step: get the top-level Guest page table entry. */
gpgd = __pgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
kill_guest(lg, "Bad address %#lx", vaddr);
gpte = __pte(lgread_u32(lg, gpte_addr(lg, gpgd, vaddr)));
gpte = lgread(lg, gpte_addr(lg, gpgd, vaddr), pte_t);
if (!(pte_flags(gpte) & _PAGE_PRESENT))
kill_guest(lg, "Bad address %#lx", vaddr);
......
......@@ -150,7 +150,7 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
kill_guest(lg, "too many gdt entries %i", num);
/* We read the whole thing in, then fix it up. */
lgread(lg, lg->arch.gdt, table, num * sizeof(lg->arch.gdt[0]));
__lgread(lg, lg->arch.gdt, table, num * sizeof(lg->arch.gdt[0]));
fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->arch.gdt));
/* Mark that the GDT changed so the core knows it has to copy it again,
* even if the Guest is run on the same CPU. */
......@@ -161,7 +161,7 @@ void guest_load_tls(struct lguest *lg, unsigned long gtls)
{
struct desc_struct *tls = &lg->arch.gdt[GDT_ENTRY_TLS_MIN];
lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
__lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
fixup_gdt_table(lg, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
lg->changed |= CHANGED_GDT_TLS;
}
......
......@@ -222,7 +222,7 @@ static int emulate_insn(struct lguest *lg)
return 0;
/* Decoding x86 instructions is icky. */
lgread(lg, &insn, physaddr, 1);
insn = lgread(lg, physaddr, u8);
/* 0x66 is an "operand prefix". It means it's using the upper 16 bits
of the eax register. */
......@@ -230,7 +230,7 @@ static int emulate_insn(struct lguest *lg)
shift = 16;
/* The instruction is 1 byte so far, read the next byte. */
insnlen = 1;
lgread(lg, &insn, physaddr + insnlen, 1);
insn = lgread(lg, physaddr + insnlen, u8);
}
/* We can ignore the lower bit for the moment and decode the 4 opcodes
......
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