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Message-Id: <1682554137-13938-21-git-send-email-anthony.yznaga@oracle.com>
Date: Wed, 26 Apr 2023 17:08:56 -0700
From: Anthony Yznaga <anthony.yznaga@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
hpa@...or.com, dave.hansen@...ux.intel.com, luto@...nel.org,
peterz@...radead.org, rppt@...nel.org, akpm@...ux-foundation.org,
ebiederm@...ssion.com, keescook@...omium.org, graf@...zon.com,
jason.zeng@...el.com, lei.l.li@...el.com,
steven.sistare@...cle.com, fam.zheng@...edance.com,
mgalaxy@...mai.com, kexec@...ts.infradead.org
Subject: [RFC v3 20/21] x86/KASLR: PKRAM: support physical kaslr
Avoid regions of memory that contain preserved pages when computing
slots used to select where to put the decompressed kernel.
Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com>
---
arch/x86/boot/compressed/Makefile | 3 ++
arch/x86/boot/compressed/kaslr.c | 10 +++-
arch/x86/boot/compressed/misc.h | 10 ++++
arch/x86/boot/compressed/pkram.c | 110 ++++++++++++++++++++++++++++++++++++++
mm/pkram.c | 2 +-
5 files changed, 132 insertions(+), 3 deletions(-)
create mode 100644 arch/x86/boot/compressed/pkram.c
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 6b6cfe607bdb..d9a5af94a797 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -103,6 +103,9 @@ ifdef CONFIG_X86_64
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/mem_encrypt.o
vmlinux-objs-y += $(obj)/pgtable_64.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o
+ifdef CONFIG_RANDOMIZE_BASE
+ vmlinux-objs-$(CONFIG_PKRAM) += $(obj)/pkram.o
+endif
endif
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 454757fbdfe5..047b8b9a0799 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -436,6 +436,7 @@ static bool mem_avoid_overlap(struct mem_vector *img,
struct setup_data *ptr;
u64 earliest = img->start + img->size;
bool is_overlapping = false;
+ struct mem_vector avoid;
for (i = 0; i < MEM_AVOID_MAX; i++) {
if (mem_overlaps(img, &mem_avoid[i]) &&
@@ -449,8 +450,6 @@ static bool mem_avoid_overlap(struct mem_vector *img,
/* Avoid all entries in the setup_data linked list. */
ptr = (struct setup_data *)(unsigned long)boot_params->hdr.setup_data;
while (ptr) {
- struct mem_vector avoid;
-
avoid.start = (unsigned long)ptr;
avoid.size = sizeof(*ptr) + ptr->len;
@@ -475,6 +474,12 @@ static bool mem_avoid_overlap(struct mem_vector *img,
ptr = (struct setup_data *)(unsigned long)ptr->next;
}
+ if (pkram_has_overlap(img, &avoid) && (avoid.start < earliest)) {
+ *overlap = avoid;
+ earliest = overlap->start;
+ is_overlapping = true;
+ }
+
return is_overlapping;
}
@@ -836,6 +841,7 @@ void choose_random_location(unsigned long input,
return;
}
+ pkram_init();
boot_params->hdr.loadflags |= KASLR_FLAG;
if (IS_ENABLED(CONFIG_X86_32))
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 20118fb7c53b..01ff5e507064 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -124,6 +124,16 @@ static inline void console_init(void)
{ }
#endif
+#ifdef CONFIG_PKRAM
+void pkram_init(void);
+int pkram_has_overlap(struct mem_vector *entry, struct mem_vector *overlap);
+#else
+static inline void pkram_init(void) { }
+static inline int pkram_has_overlap(struct mem_vector *entry,
+ struct mem_vector *overlap)
+{ return 0; }
+#endif
+
#ifdef CONFIG_AMD_MEM_ENCRYPT
void sev_enable(struct boot_params *bp);
void snp_check_features(void);
diff --git a/arch/x86/boot/compressed/pkram.c b/arch/x86/boot/compressed/pkram.c
new file mode 100644
index 000000000000..19267ca2ce8e
--- /dev/null
+++ b/arch/x86/boot/compressed/pkram.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "misc.h"
+
+#define PKRAM_MAGIC 0x706B726D
+
+struct pkram_super_block {
+ __u32 magic;
+
+ __u64 node_pfn;
+ __u64 region_list_pfn;
+ __u64 nr_regions;
+};
+
+struct pkram_region {
+ phys_addr_t base;
+ phys_addr_t size;
+};
+
+struct pkram_region_list {
+ __u64 prev_pfn;
+ __u64 next_pfn;
+
+ struct pkram_region regions[0];
+};
+
+#define PKRAM_REGIONS_LIST_MAX \
+ ((PAGE_SIZE-sizeof(struct pkram_region_list))/sizeof(struct pkram_region))
+
+static u64 pkram_sb_pfn;
+static struct pkram_super_block *pkram_sb;
+
+void pkram_init(void)
+{
+ struct pkram_super_block *sb;
+ char arg[32];
+
+ if (cmdline_find_option("pkram", arg, sizeof(arg)) > 0) {
+ if (kstrtoull(arg, 16, &pkram_sb_pfn) != 0)
+ return;
+ } else
+ return;
+
+ sb = (struct pkram_super_block *)(pkram_sb_pfn << PAGE_SHIFT);
+ if (sb->magic != PKRAM_MAGIC) {
+ debug_putstr("PKRAM: invalid super block\n");
+ return;
+ }
+
+ pkram_sb = sb;
+}
+
+static struct pkram_region *pkram_first_region(struct pkram_super_block *sb,
+ struct pkram_region_list **rlp, int *idx)
+{
+ if (!sb || !sb->region_list_pfn)
+ return NULL;
+
+ *rlp = (struct pkram_region_list *)(sb->region_list_pfn << PAGE_SHIFT);
+ *idx = 0;
+
+ return &(*rlp)->regions[0];
+}
+
+static struct pkram_region *pkram_next_region(struct pkram_region_list **rlp, int *idx)
+{
+ struct pkram_region_list *rl = *rlp;
+ int i = *idx;
+
+ i++;
+ if (i >= PKRAM_REGIONS_LIST_MAX) {
+ if (!rl->next_pfn) {
+ debug_putstr("PKRAM: no more pkram_region_list pages\n");
+ return NULL;
+ }
+ rl = (struct pkram_region_list *)(rl->next_pfn << PAGE_SHIFT);
+ *rlp = rl;
+ i = 0;
+ }
+ *idx = i;
+
+ if (rl->regions[i].size == 0)
+ return NULL;
+
+ return &rl->regions[i];
+}
+
+int pkram_has_overlap(struct mem_vector *entry, struct mem_vector *overlap)
+{
+ struct pkram_region_list *rl;
+ struct pkram_region *r;
+ int idx;
+
+ r = pkram_first_region(pkram_sb, &rl, &idx);
+
+ while (r) {
+ if (r->base + r->size <= entry->start) {
+ r = pkram_next_region(&rl, &idx);
+ continue;
+ }
+ if (r->base >= entry->start + entry->size)
+ return 0;
+
+ overlap->start = r->base;
+ overlap->size = r->size;
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/mm/pkram.c b/mm/pkram.c
index f38236e5d836..a3e045b8dfe4 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -96,7 +96,7 @@ struct pkram_region_list {
__u64 prev_pfn;
__u64 next_pfn;
- struct pkram_region regions[0];
+ struct pkram_region regions[];
};
#define PKRAM_REGIONS_LIST_MAX \
--
1.9.4
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