diff options
| -rw-r--r-- | drivers/lguest/page_tables.c | 37 |
1 files changed, 16 insertions, 21 deletions
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index 3b62be160a6e..a2454a24a10c 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -95,13 +95,6 @@ static pgd_t *spgd_addr(struct lg_cpu *cpu, u32 i, unsigned long vaddr) { unsigned int index = pgd_index(vaddr); -#ifndef CONFIG_X86_PAE - /* We kill any Guest trying to touch the Switcher addresses. */ - if (index >= SWITCHER_PGD_INDEX) { - kill_guest(cpu, "attempt to access switcher pages"); - index = 0; - } -#endif /* Return a pointer index'th pgd entry for the i'th page table. */ return &cpu->lg->pgdirs[i].pgdir[index]; } @@ -117,13 +110,6 @@ static pmd_t *spmd_addr(struct lg_cpu *cpu, pgd_t spgd, unsigned long vaddr) unsigned int index = pmd_index(vaddr); pmd_t *page; - /* We kill any Guest trying to touch the Switcher addresses. */ - if (pgd_index(vaddr) == SWITCHER_PGD_INDEX && - index >= SWITCHER_PMD_INDEX) { - kill_guest(cpu, "attempt to access switcher pages"); - index = 0; - } - /* You should never call this if the PGD entry wasn't valid */ BUG_ON(!(pgd_flags(spgd) & _PAGE_PRESENT)); page = __va(pgd_pfn(spgd) << PAGE_SHIFT); @@ -323,6 +309,10 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) pmd_t gpmd; #endif + /* We never demand page the Switcher, so trying is a mistake. */ + if (vaddr >= switcher_addr) + return false; + /* First step: get the top-level Guest page table entry. */ if (unlikely(cpu->linear_pages)) { /* Faking up a linear mapping. */ @@ -495,10 +485,14 @@ static bool page_writable(struct lg_cpu *cpu, unsigned long vaddr) { pgd_t *spgd; unsigned long flags; - #ifdef CONFIG_X86_PAE pmd_t *spmd; #endif + + /* You can't put your stack in the Switcher! */ + if (vaddr >= switcher_addr) + return false; + /* Look at the current top level entry: is it present? */ spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr); if (!(pgd_flags(*spgd) & _PAGE_PRESENT)) @@ -897,6 +891,12 @@ static void do_set_pte(struct lg_cpu *cpu, int idx, void guest_set_pte(struct lg_cpu *cpu, unsigned long gpgdir, unsigned long vaddr, pte_t gpte) { + /* We don't let you remap the Switcher; we need it to get back! */ + if (vaddr >= switcher_addr) { + kill_guest(cpu, "attempt to set pte into Switcher pages"); + return; + } + /* * Kernel mappings must be changed on all top levels. Slow, but doesn't * happen often. @@ -995,12 +995,7 @@ void page_table_guest_data_init(struct lg_cpu *cpu) * "pgd_index(lg->kernel_address)". This assumes it won't hit the * Switcher mappings, so check that now. */ -#ifdef CONFIG_X86_PAE - if (pgd_index(cpu->lg->kernel_address) == SWITCHER_PGD_INDEX && - pmd_index(cpu->lg->kernel_address) == SWITCHER_PMD_INDEX) -#else - if (pgd_index(cpu->lg->kernel_address) >= SWITCHER_PGD_INDEX) -#endif + if (cpu->lg->kernel_address >= switcher_addr) kill_guest(cpu, "bad kernel address %#lx", cpu->lg->kernel_address); } |