Commit-ID: 9bae3197e15dd5e03ce8e237db6fe4486b08a775
Gitweb: https://git.kernel.org/tip/9bae3197e15dd5e03ce8e237db6fe4486b08a775
Author: Joerg Roedel <jroedel@xxxxxxx>
AuthorDate: Wed, 18 Jul 2018 11:41:12 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 20 Jul 2018 01:11:47 +0200
x86/ldt: Split out sanity check in map_ldt_struct()
This splits out the mapping sanity check and the actual mapping of the LDT
to user-space from the map_ldt_struct() function in a way so that it is
re-usable for PAE paging.
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Pavel Machek <pavel@xxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Eduardo Valentin <eduval@xxxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: aliguori@xxxxxxxxxx
Cc: daniel.gruss@xxxxxxxxxxxxxx
Cc: hughd@xxxxxxxxxx
Cc: keescook@xxxxxxxxxx
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Waiman Long <llong@xxxxxxxxxx>
Cc: "David H . Gutteridge" <dhgutteridge@xxxxxxxxxxxx>
Cc: joro@xxxxxxxxxx
Link: https://lkml.kernel.org/r/1531906876-13451-36-git-send-email-joro@xxxxxxxxxx
---
arch/x86/kernel/ldt.c | 82 ++++++++++++++++++++++++++++++++++++---------------
1 file changed, 58 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index e921b3d494d5..69af9a0d57b7 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -100,6 +100,49 @@ static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries)
return new_ldt;
}
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+
+static void do_sanity_check(struct mm_struct *mm,
+ bool had_kernel_mapping,
+ bool had_user_mapping)
+{
+ if (mm->context.ldt) {
+ /*
+ * We already had an LDT. The top-level entry should already
+ * have been allocated and synchronized with the usermode
+ * tables.
+ */
+ WARN_ON(!had_kernel_mapping);
+ if (static_cpu_has(X86_FEATURE_PTI))
+ WARN_ON(!had_user_mapping);
+ } else {
+ /*
+ * This is the first time we're mapping an LDT for this process.
+ * Sync the pgd to the usermode tables.
+ */
+ WARN_ON(had_kernel_mapping);
+ if (static_cpu_has(X86_FEATURE_PTI))
+ WARN_ON(had_user_mapping);
+ }
+}
+
+static void map_ldt_struct_to_user(struct mm_struct *mm)
+{
+ pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR);
+
+ if (static_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt)
+ set_pgd(kernel_to_user_pgdp(pgd), *pgd);
+}
+
+static void sanity_check_ldt_mapping(struct mm_struct *mm)
+{
+ pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ bool had_kernel = (pgd->pgd != 0);
+ bool had_user = (kernel_to_user_pgdp(pgd)->pgd != 0);
+
+ do_sanity_check(mm, had_kernel, had_user);
+}
+
/*
* If PTI is enabled, this maps the LDT into the kernelmode and
* usermode tables for the given mm.
@@ -115,9 +158,8 @@ static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries)
static int
map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
{
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
- bool is_vmalloc, had_top_level_entry;
unsigned long va;
+ bool is_vmalloc;
spinlock_t *ptl;
pgd_t *pgd;
int i;
@@ -131,13 +173,15 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
*/
WARN_ON(ldt->slot != -1);
+ /* Check if the current mappings are sane */
+ sanity_check_ldt_mapping(mm);
+
/*
* Did we already have the top level entry allocated? We can't
* use pgd_none() for this because it doens't do anything on
* 4-level page table kernels.
*/
pgd = pgd_offset(mm, LDT_BASE_ADDR);
- had_top_level_entry = (pgd->pgd != 0);
is_vmalloc = is_vmalloc_addr(ldt->entries);
@@ -172,35 +216,25 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
pte_unmap_unlock(ptep, ptl);
}
- if (mm->context.ldt) {
- /*
- * We already had an LDT. The top-level entry should already
- * have been allocated and synchronized with the usermode
- * tables.
- */
- WARN_ON(!had_top_level_entry);
- if (static_cpu_has(X86_FEATURE_PTI))
- WARN_ON(!kernel_to_user_pgdp(pgd)->pgd);
- } else {
- /*
- * This is the first time we're mapping an LDT for this process.
- * Sync the pgd to the usermode tables.
- */
- WARN_ON(had_top_level_entry);
- if (static_cpu_has(X86_FEATURE_PTI)) {
- WARN_ON(kernel_to_user_pgdp(pgd)->pgd);
- set_pgd(kernel_to_user_pgdp(pgd), *pgd);
- }
- }
+ /* Propagate LDT mapping to the user page-table */
+ map_ldt_struct_to_user(mm);
va = (unsigned long)ldt_slot_va(slot);
flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, 0);
ldt->slot = slot;
-#endif
return 0;
}
+#else /* !CONFIG_PAGE_TABLE_ISOLATION */
+
+static int
+map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
+{
+ return 0;
+}
+#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+
static void free_ldt_pgtables(struct mm_struct *mm)
{
#ifdef CONFIG_PAGE_TABLE_ISOLATION
--
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