diff options
Diffstat (limited to 'arch/x86/kernel/ldt.c')
| -rw-r--r-- | arch/x86/kernel/ldt.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index 69af9a0d57b7..733e6ace0fa4 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -126,6 +126,57 @@ static void do_sanity_check(struct mm_struct *mm, } } +#ifdef CONFIG_X86_PAE + +static pmd_t *pgd_to_pmd_walk(pgd_t *pgd, unsigned long va) +{ + p4d_t *p4d; + pud_t *pud; + + if (pgd->pgd == 0) + return NULL; + + p4d = p4d_offset(pgd, va); + if (p4d_none(*p4d)) + return NULL; + + pud = pud_offset(p4d, va); + if (pud_none(*pud)) + return NULL; + + return pmd_offset(pud, va); +} + +static void map_ldt_struct_to_user(struct mm_struct *mm) +{ + pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR); + pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd); + pmd_t *k_pmd, *u_pmd; + + k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR); + u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR); + + if (static_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt) + set_pmd(u_pmd, *k_pmd); +} + +static void sanity_check_ldt_mapping(struct mm_struct *mm) +{ + pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR); + pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd); + bool had_kernel, had_user; + pmd_t *k_pmd, *u_pmd; + + k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR); + u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR); + had_kernel = (k_pmd->pmd != 0); + had_user = (u_pmd->pmd != 0); + + do_sanity_check(mm, had_kernel, had_user); +} + +#else /* !CONFIG_X86_PAE */ + static void map_ldt_struct_to_user(struct mm_struct *mm) { pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR); @@ -143,6 +194,8 @@ static void sanity_check_ldt_mapping(struct mm_struct *mm) do_sanity_check(mm, had_kernel, had_user); } +#endif /* CONFIG_X86_PAE */ + /* * If PTI is enabled, this maps the LDT into the kernelmode and * usermode tables for the given mm. |