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Message-Id: <1520245563-8444-32-git-send-email-joro@8bytes.org>
Date: Mon, 5 Mar 2018 11:26:00 +0100
From: Joerg Roedel <joro@...tes.org>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
"H . Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...el.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Juergen Gross <jgross@...e.com>,
Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Brian Gerst <brgerst@...il.com>,
David Laight <David.Laight@...lab.com>,
Denys Vlasenko <dvlasenk@...hat.com>,
Eduardo Valentin <eduval@...zon.com>,
Greg KH <gregkh@...uxfoundation.org>,
Will Deacon <will.deacon@....com>, aliguori@...zon.com,
daniel.gruss@...k.tugraz.at, hughd@...gle.com, keescook@...gle.com,
Andrea Arcangeli <aarcange@...hat.com>,
Waiman Long <llong@...hat.com>, Pavel Machek <pavel@....cz>,
jroedel@...e.de, joro@...tes.org
Subject: [PATCH 31/34] x86/ldt: Split out sanity check in map_ldt_struct()
From: Joerg Roedel <jroedel@...e.de>
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@...e.de>
---
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 f3c2fbf..8ab7df9 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);
@@ -168,35 +212,25 @@ 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
--
2.7.4
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