From: Arvind Sankar <nivedita@alum.mit.edu>
To: x86@kernel.org, Joerg Roedel <jroedel@suse.de>,
Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] x86/boot/64: Initialize 5-level paging variables earlier
Date: Sat, 10 Oct 2020 15:11:10 -0400 [thread overview]
Message-ID: <20201010191110.4060905-1-nivedita@alum.mit.edu> (raw)
In-Reply-To: <20201008191623.2881677-1-nivedita@alum.mit.edu>
Commit
ca0e22d4f011 ("x86/boot/compressed/64: Always switch to own page table")
started using a new set of pagetables even without KASLR.
After that commit, initialize_identity_maps() is called before the
5-level paging variables are setup in choose_random_location(), which
will not work if 5-level paging is actually enabled.
Fix this by moving the initialization of __pgtable_l5_enabled,
pgdir_shift and ptrs_per_p4d into cleanup_trampoline(), which is called
immediately after the finalization of whether the kernel is executing
with 4- or 5-level paging. This will be earlier than anything that might
require those variables, and keeps the 4- vs 5-level paging code all in
one place.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
arch/x86/boot/compressed/ident_map_64.c | 6 ------
arch/x86/boot/compressed/kaslr.c | 8 --------
arch/x86/boot/compressed/pgtable_64.c | 16 ++++++++++++++++
3 files changed, 16 insertions(+), 14 deletions(-)
diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index a3613857c532..505d6299b76e 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -34,12 +34,6 @@
#define __PAGE_OFFSET __PAGE_OFFSET_BASE
#include "../../mm/ident_map.c"
-#ifdef CONFIG_X86_5LEVEL
-unsigned int __pgtable_l5_enabled;
-unsigned int pgdir_shift = 39;
-unsigned int ptrs_per_p4d = 1;
-#endif
-
/* Used by PAGE_KERN* macros: */
pteval_t __default_kernel_pte_mask __read_mostly = ~0;
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 489fabc051d7..9eabd8bc7673 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -835,14 +835,6 @@ void choose_random_location(unsigned long input,
return;
}
-#ifdef CONFIG_X86_5LEVEL
- if (__read_cr4() & X86_CR4_LA57) {
- __pgtable_l5_enabled = 1;
- pgdir_shift = 48;
- ptrs_per_p4d = 512;
- }
-#endif
-
boot_params->hdr.loadflags |= KASLR_FLAG;
if (IS_ENABLED(CONFIG_X86_32))
diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index 46d761f7faa6..0976c2d2ab2f 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -9,6 +9,13 @@
#define BIOS_START_MIN 0x20000U /* 128K, less than this is insane */
#define BIOS_START_MAX 0x9f000U /* 640K, absolute maximum */
+#ifdef CONFIG_X86_5LEVEL
+/* __pgtable_l5_enabled needs to be in .data to avoid being cleared along with .bss */
+unsigned int __section(.data) __pgtable_l5_enabled;
+unsigned int __section(.data) pgdir_shift = 39;
+unsigned int __section(.data) ptrs_per_p4d = 1;
+#endif
+
struct paging_config {
unsigned long trampoline_start;
unsigned long l5_required;
@@ -195,4 +202,13 @@ void cleanup_trampoline(void *pgtable)
/* Restore trampoline memory */
memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);
+
+ /* Initialize variables for 5-level paging */
+#ifdef CONFIG_X86_5LEVEL
+ if (__read_cr4() & X86_CR4_LA57) {
+ __pgtable_l5_enabled = 1;
+ pgdir_shift = 48;
+ ptrs_per_p4d = 512;
+ }
+#endif
}
--
2.26.2
next prev parent reply other threads:[~2020-10-10 23:14 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 19:16 [PATCH v2 0/5] Couple of bugfixes to sev-es series Arvind Sankar
2020-10-08 19:16 ` [PATCH v2 1/5] x86/boot: Initialize boot_params in startup code Arvind Sankar
2020-10-08 19:16 ` [PATCH v2 2/5] x86/boot: Split out command-line related declarations Arvind Sankar
2020-10-08 19:16 ` [PATCH v2 3/5] x86/boot/64: Show original faulting address in case of error Arvind Sankar
2020-10-09 14:42 ` Joerg Roedel
2020-10-08 19:16 ` [PATCH v2 4/5] x86/boot/64: Explicitly map boot_params and command line Arvind Sankar
2020-10-09 14:49 ` Joerg Roedel
2020-10-16 16:27 ` Borislav Petkov
2020-10-16 16:47 ` Arvind Sankar
2020-10-16 17:07 ` Borislav Petkov
2020-10-16 17:20 ` Arvind Sankar
2020-10-16 17:32 ` Borislav Petkov
2020-10-16 20:04 ` [PATCH v3 1/4] " Arvind Sankar
2020-10-16 20:04 ` [PATCH v3 2/4] x86/boot: Initialize boot_params in startup code Arvind Sankar
2020-10-16 20:04 ` [PATCH v3 3/4] x86/boot: Split out command-line related declarations Arvind Sankar
2020-10-16 20:04 ` [PATCH v3 4/4] x86/boot/64: Show original faulting address in case of error Arvind Sankar
2020-10-19 14:51 ` [PATCH v3 1/4] x86/boot/64: Explicitly map boot_params and command line Borislav Petkov
2020-10-19 17:12 ` Arvind Sankar
2020-10-19 17:31 ` Borislav Petkov
2020-10-19 19:44 ` [tip: x86/seves] " tip-bot2 for Arvind Sankar
2020-10-16 21:18 ` [PATCH v2 4/5] " Arvind Sankar
2020-10-16 21:23 ` Borislav Petkov
2020-10-08 19:16 ` [PATCH v2 5/5] x86/head/64: Disable stack protection for head$(BITS).o Arvind Sankar
2020-10-09 14:49 ` Joerg Roedel
2020-10-16 11:17 ` Borislav Petkov
2020-10-16 12:43 ` Arvind Sankar
2020-10-16 13:15 ` Borislav Petkov
2020-10-16 14:16 ` Arvind Sankar
2020-10-19 19:44 ` [tip: x86/seves] " tip-bot2 for Arvind Sankar
2020-10-10 19:11 ` Arvind Sankar [this message]
2020-10-10 19:26 ` [PATCH] x86/boot/64: Initialize 5-level paging variables earlier Arvind Sankar
2020-10-12 14:08 ` Kirill A. Shutemov
2020-10-12 15:35 ` Arvind Sankar
2020-10-13 8:11 ` Borislav Petkov
2020-10-13 8:20 ` Kirill A. Shutemov
2020-10-13 8:33 ` Borislav Petkov
2020-10-13 9:12 ` Kirill A. Shutemov
2020-10-13 9:46 ` Borislav Petkov
2020-10-15 13:52 ` Kirill A. Shutemov
2020-10-16 10:21 ` Borislav Petkov
2020-10-13 8:59 ` Joerg Roedel
2020-10-19 19:44 ` [tip: x86/seves] " tip-bot2 for Arvind Sankar
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