From: Dave Hansen <dave.han...@linux.intel.com>
A few PGDs come out of the kernel binary instead of being
allocated dynamically. Before this patch, they are all
8k-aligned, but they must also be 8k in *size*.
The original KAISER patch did not do this. It probably just
lucked out that it did not trample over data after the last PGD.
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
Cc: Moritz Lipp <moritz.l...@iaik.tugraz.at>
Cc: Daniel Gruss <daniel.gr...@iaik.tugraz.at>
Cc: Michael Schwarz <michael.schw...@iaik.tugraz.at>
Cc: Richard Fellner <richard.fell...@student.tugraz.at>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Kees Cook <keesc...@google.com>
Cc: Hugh Dickins <hu...@google.com>
Cc: x...@kernel.org
---
b/arch/x86/kernel/head_64.S | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff -puN arch/x86/kernel/head_64.S~kaiser-head_S-pgds-need-8k-too
arch/x86/kernel/head_64.S
--- a/arch/x86/kernel/head_64.S~kaiser-head_S-pgds-need-8k-too 2017-11-22
15:45:47.913619742 -0800
+++ b/arch/x86/kernel/head_64.S 2017-11-22 15:45:47.916619742 -0800
@@ -342,11 +342,24 @@ GLOBAL(early_recursion_flag)
GLOBAL(name)
#ifdef CONFIG_KAISER
+/*
+ * Each PGD needs to be 8k long and 8k aligned. We do not
+ * ever go out to userspace with these, so we do not
+ * strictly *need* the second page, but this allows us to
+ * have a single set_pgd() implementation that does not
+ * need to worry about whether it has 4k or 8k to work
+ * with.
+ *
+ * This ensures PGDs are 8k long:
+ */
+#define KAISER_USER_PGD_FILL 512
+/* This ensures they are 8k-aligned: */
#define NEXT_PGD_PAGE(name) \
.balign 2 * PAGE_SIZE; \
GLOBAL(name)
#else
#define NEXT_PGD_PAGE(name) NEXT_PAGE(name)
+#define KAISER_USER_PGD_FILL 0
#endif
/* Automate the creation of 1 to 1 mapping pmd entries */
@@ -365,6 +378,7 @@ NEXT_PGD_PAGE(early_top_pgt)
#else
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
#endif
+ .fill KAISER_USER_PGD_FILL,8,0
NEXT_PAGE(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
@@ -379,6 +393,7 @@ NEXT_PGD_PAGE(init_top_pgt)
.org init_top_pgt + PGD_START_KERNEL*8, 0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
+ .fill KAISER_USER_PGD_FILL,8,0
NEXT_PAGE(level3_ident_pgt)
.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
@@ -391,6 +406,7 @@ NEXT_PAGE(level2_ident_pgt)
#else
NEXT_PGD_PAGE(init_top_pgt)
.fill 512,8,0
+ .fill KAISER_USER_PGD_FILL,8,0
#endif
#ifdef CONFIG_X86_5LEVEL
_
