Firmware is responsible for accepting memory where compressed kernel
image and initrd land. But kernel has to accept memory for decompression
buffer: accept memory just before decompression starts
KASLR allowed to use unaccepted memory for output buffer.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/bitmap.c | 62 ++++++++++++++++++++
arch/x86/boot/compressed/kaslr.c | 14 ++++-
arch/x86/boot/compressed/misc.c | 9 +++
arch/x86/boot/compressed/unaccepted_memory.c | 13 ++++
arch/x86/include/asm/unaccepted_memory.h | 2 +
5 files changed, 98 insertions(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/bitmap.c b/arch/x86/boot/compressed/bitmap.c
index bf58b259380a..ba2de61c0823 100644
--- a/arch/x86/boot/compressed/bitmap.c
+++ b/arch/x86/boot/compressed/bitmap.c
@@ -2,6 +2,48 @@
/* Taken from lib/string.c */
#include <linux/bitmap.h>
+#include <linux/math.h>
+#include <linux/minmax.h>
+
+unsigned long _find_next_bit(const unsigned long *addr1,
+ const unsigned long *addr2, unsigned long nbits,
+ unsigned long start, unsigned long invert, unsigned long le)
+{
+ unsigned long tmp, mask;
+
+ if (unlikely(start >= nbits))
+ return nbits;
+
+ tmp = addr1[start / BITS_PER_LONG];
+ if (addr2)
+ tmp &= addr2[start / BITS_PER_LONG];
+ tmp ^= invert;
+
+ /* Handle 1st word. */
+ mask = BITMAP_FIRST_WORD_MASK(start);
+ if (le)
+ mask = swab(mask);
+
+ tmp &= mask;
+
+ start = round_down(start, BITS_PER_LONG);
+
+ while (!tmp) {
+ start += BITS_PER_LONG;
+ if (start >= nbits)
+ return nbits;
+
+ tmp = addr1[start / BITS_PER_LONG];
+ if (addr2)
+ tmp &= addr2[start / BITS_PER_LONG];
+ tmp ^= invert;
+ }
+
+ if (le)
+ tmp = swab(tmp);
+
+ return min(start + __ffs(tmp), nbits);
+}
void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
@@ -22,3 +64,23 @@ void __bitmap_set(unsigned long *map, unsigned int start, int len)
*p |= mask_to_set;
}
}
+
+void __bitmap_clear(unsigned long *map, unsigned int start, int len)
+{
+ unsigned long *p = map + BIT_WORD(start);
+ const unsigned int size = start + len;
+ int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+ unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+ while (len - bits_to_clear >= 0) {
+ *p &= ~mask_to_clear;
+ len -= bits_to_clear;
+ bits_to_clear = BITS_PER_LONG;
+ mask_to_clear = ~0UL;
+ p++;
+ }
+ if (len) {
+ mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+ *p &= ~mask_to_clear;
+ }
+}
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index e36690778497..89cdc17dcbf1 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -729,10 +729,20 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
* but in practice there's firmware where using that memory leads
* to crashes.
*
- * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free.
+ * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if
+ * supported) are guaranteed to be free.
*/
- if (md->type != EFI_CONVENTIONAL_MEMORY)
+
+ switch (md->type) {
+ case EFI_CONVENTIONAL_MEMORY:
+ break;
+ case EFI_UNACCEPTED_MEMORY:
+ if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
+ break;
continue;
+ default:
+ continue;
+ }
if (efi_soft_reserve_enabled() &&
(md->attribute & EFI_MEMORY_SP))
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 743f13ea25c1..eeefcde8394d 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -18,6 +18,7 @@
#include "../string.h"
#include "../voffset.h"
#include <asm/bootparam_utils.h>
+#include <asm/unaccepted_memory.h>
/*
* WARNING!!
@@ -435,6 +436,14 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
#endif
debug_putstr("\nDecompressing Linux... ");
+
+ if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) &&
+ boot_params->unaccepted_memory) {
+ debug_putstr("Accepting memory... ");
+ accept_memory((phys_addr_t)output,
+ (phys_addr_t)output + needed_size);
+ }
+
__decompress(input_data, input_len, NULL, NULL, output, output_len,
NULL, error);
parse_elf(output);
diff --git a/arch/x86/boot/compressed/unaccepted_memory.c b/arch/x86/boot/compressed/unaccepted_memory.c
index c2eca85b5073..17b70627b0cd 100644
--- a/arch/x86/boot/compressed/unaccepted_memory.c
+++ b/arch/x86/boot/compressed/unaccepted_memory.c
@@ -34,3 +34,16 @@ void mark_unaccepted(struct boot_params *params, u64 start, u64 num)
bitmap_set((unsigned long *)params->unaccepted_memory,
start / PMD_SIZE, npages);
}
+
+void accept_memory(phys_addr_t start, phys_addr_t end)
+{
+ unsigned long *unaccepted_memory;
+ unsigned int rs, re;
+
+ unaccepted_memory = (unsigned long *)boot_params->unaccepted_memory;
+ bitmap_for_each_set_region(unaccepted_memory, rs, re,
+ start / PMD_SIZE, end / PMD_SIZE) {
+ __accept_memory(rs * PMD_SIZE, re * PMD_SIZE);
+ bitmap_clear(unaccepted_memory, rs, re - rs);
+ }
+}
diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/asm/unaccepted_memory.h
index cbc24040b853..f1f835d3cd78 100644
--- a/arch/x86/include/asm/unaccepted_memory.h
+++ b/arch/x86/include/asm/unaccepted_memory.h
@@ -9,4 +9,6 @@ struct boot_params;
void mark_unaccepted(struct boot_params *params, u64 start, u64 num);
+void accept_memory(phys_addr_t start, phys_addr_t end);
+
#endif
--
2.31.1
