@@ -81,7 +81,6 @@
* x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
* x22 create_idmap() .. start_kernel() ID map VA of the DT blob
* x23 __primary_switch() physical misalignment/KASLR offset
- * x24 __primary_switch() linear map KASLR seed
* x25 primary_entry() .. start_kernel() supported VA size
* x28 create_idmap() callee preserved temp register
*/
@@ -431,11 +430,6 @@ SYM_FUNC_START_LOCAL(__primary_switched)
str x25, [x8] // ... observes the correct value
dc civac, x8 // Make visible to booting secondaries
#endif
-
-#ifdef CONFIG_RANDOMIZE_BASE
- adrp x5, memstart_offset_seed // Save KASLR linear map seed
- strh w24, [x5, :lo12:memstart_offset_seed]
-#endif
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
bl kasan_early_init
#endif
@@ -705,7 +699,6 @@ SYM_FUNC_START_LOCAL(__primary_switch)
#ifdef CONFIG_RANDOMIZE_BASE
mov x0, x22
bl __pi_kaslr_early_init
- and x24, x0, #SZ_2M - 1 // capture memstart offset seed
bic x0, x0, #SZ_2M - 1
orr x23, x23, x0 // record kernel offset
#endif
@@ -41,6 +41,8 @@ PROVIDE(__pi___memcpy = __pi_memcpy);
PROVIDE(__pi___memmove = __pi_memmove);
PROVIDE(__pi___memset = __pi_memset);
+PROVIDE(__pi_memstart_offset_seed = memstart_offset_seed);
+
PROVIDE(__pi_id_aa64isar1_override = id_aa64isar1_override);
PROVIDE(__pi_id_aa64isar2_override = id_aa64isar2_override);
PROVIDE(__pi_id_aa64mmfr1_override = id_aa64mmfr1_override);
@@ -21,7 +21,7 @@
#include <asm/setup.h>
u64 __ro_after_init module_alloc_base;
-u16 __initdata memstart_offset_seed;
+u16 memstart_offset_seed;
static int __init kaslr_init(void)
{
@@ -15,6 +15,8 @@
#include <asm/archrandom.h>
#include <asm/memory.h>
+extern u16 memstart_offset_seed;
+
static u64 __init get_kaslr_seed(void *fdt)
{
static char const chosen_str[] __initconst = "chosen";
@@ -51,6 +53,8 @@ asmlinkage u64 __init kaslr_early_init(void *fdt)
return 0;
}
+ memstart_offset_seed = seed & U16_MAX;
+
/*
* OK, so we are proceeding with KASLR enabled. Calculate a suitable
* kernel image offset from the seed. Let's place the kernel in the
@@ -58,5 +62,5 @@ asmlinkage u64 __init kaslr_early_init(void *fdt)
* the lower and upper quarters to avoid colliding with other
* allocations.
*/
- return BIT(VA_BITS_MIN - 3) + (seed & GENMASK(VA_BITS_MIN - 3, 0));
+ return BIT(VA_BITS_MIN - 3) + (seed & GENMASK(VA_BITS_MIN - 3, 16));
}
Now that we can set BSS variables from the early code running from the ID map, we can set memstart_offset_seed directly from the C code that derives the value instead of passing it back and forth between C and asm code. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/kernel/head.S | 7 ------- arch/arm64/kernel/image-vars.h | 2 ++ arch/arm64/kernel/kaslr.c | 2 +- arch/arm64/kernel/pi/kaslr_early.c | 6 +++++- 4 files changed, 8 insertions(+), 9 deletions(-)