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Date: Tue, 30 Mar 2021 14:35:56 -0700
From: Anthony Yznaga <anthony.yznaga@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: willy@...radead.org, corbet@....net, 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, hughd@...gle.com,
ebiederm@...ssion.com, keescook@...omium.org, ardb@...nel.org,
nivedita@...m.mit.edu, jroedel@...e.de, masahiroy@...nel.org,
nathan@...nel.org, terrelln@...com, vincenzo.frascino@....com,
martin.b.radev@...il.com, andreyknvl@...gle.com,
daniel.kiper@...cle.com, rafael.j.wysocki@...el.com,
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vdavydov.dev@...il.com, graf@...zon.com, jason.zeng@...el.com,
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steven.sistare@...cle.com, linux-fsdevel@...r.kernel.org,
linux-doc@...r.kernel.org, kexec@...ts.infradead.org
Subject: [RFC v2 21/43] 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 | 109 ++++++++++++++++++++++++++++++++++++++
4 files changed, 130 insertions(+), 2 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 e0bc3988c3fa..ef27d411b641 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -93,6 +93,9 @@ ifdef CONFIG_X86_64
vmlinux-objs-y += $(obj)/mem_encrypt.o
vmlinux-objs-y += $(obj)/pgtable_64.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev-es.o
+ifdef CONFIG_RANDOMIZE_BASE
+ vmlinux-objs-$(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 b92fffbe761f..a007363a7698 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -440,6 +440,7 @@ 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]) &&
@@ -453,8 +454,6 @@ 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;
@@ -479,6 +478,12 @@ 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;
}
@@ -840,6 +845,7 @@ 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 901ea5ebec22..f8232ffd8141 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -116,6 +116,16 @@ 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
+
void set_sev_encryption_mask(void);
#ifdef CONFIG_AMD_MEM_ENCRYPT
diff --git a/arch/x86/boot/compressed/pkram.c b/arch/x86/boot/compressed/pkram.c
new file mode 100644
index 000000000000..60380f074c3f
--- /dev/null
+++ b/arch/x86/boot/compressed/pkram.c
@@ -0,0 +1,109 @@
+// 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;
+}
--
1.8.3.1
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