| Message ID | 20220613144550.3760857-9-ardb@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: refactor boot flow and add support for WXN | expand |
On 6/13/22 20:15, Ard Biesheuvel wrote: > Some early boot code runs before the virtual placement of the kernel is > finalized, and we used to go back to the very start and recreate the ID > map along with the page tables describing the virtual kernel mapping, > and this involved setting some global variables with the caches off. > > In order to ensure that global state created by the KASLR code is not > corrupted by the cache invalidation that occurs in that case, we needed > to clean those global variables to the PoC explicitly. > > This is no longer needed now that the ID map is created only once (and > the associated global variable updates are no longer repeated). So drop > the cache maintenance that is no longer necessary. > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/kernel/kaslr.c | 11 ----------- > 1 file changed, 11 deletions(-) > > diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c > index 418b2bba1521..d5542666182f 100644 > --- a/arch/arm64/kernel/kaslr.c > +++ b/arch/arm64/kernel/kaslr.c > @@ -13,7 +13,6 @@ > #include <linux/pgtable.h> > #include <linux/random.h> > > -#include <asm/cacheflush.h> > #include <asm/fixmap.h> > #include <asm/kernel-pgtable.h> > #include <asm/memory.h> > @@ -72,9 +71,6 @@ u64 __init kaslr_early_init(void) > * we end up running with module randomization disabled. > */ > module_alloc_base = (u64)_etext - MODULES_VSIZE; > - dcache_clean_inval_poc((unsigned long)&module_alloc_base, > - (unsigned long)&module_alloc_base + > - sizeof(module_alloc_base)); > > /* > * Try to map the FDT early. If this fails, we simply bail, > @@ -174,13 +170,6 @@ u64 __init kaslr_early_init(void) > module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21; > module_alloc_base &= PAGE_MASK; > > - dcache_clean_inval_poc((unsigned long)&module_alloc_base, > - (unsigned long)&module_alloc_base + > - sizeof(module_alloc_base)); > - dcache_clean_inval_poc((unsigned long)&memstart_offset_seed, > - (unsigned long)&memstart_offset_seed + > - sizeof(memstart_offset_seed)); > - > return offset; > } > Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c index 418b2bba1521..d5542666182f 100644 --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -13,7 +13,6 @@ #include <linux/pgtable.h> #include <linux/random.h> -#include <asm/cacheflush.h> #include <asm/fixmap.h> #include <asm/kernel-pgtable.h> #include <asm/memory.h> @@ -72,9 +71,6 @@ u64 __init kaslr_early_init(void) * we end up running with module randomization disabled. */ module_alloc_base = (u64)_etext - MODULES_VSIZE; - dcache_clean_inval_poc((unsigned long)&module_alloc_base, - (unsigned long)&module_alloc_base + - sizeof(module_alloc_base)); /* * Try to map the FDT early. If this fails, we simply bail, @@ -174,13 +170,6 @@ u64 __init kaslr_early_init(void) module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21; module_alloc_base &= PAGE_MASK; - dcache_clean_inval_poc((unsigned long)&module_alloc_base, - (unsigned long)&module_alloc_base + - sizeof(module_alloc_base)); - dcache_clean_inval_poc((unsigned long)&memstart_offset_seed, - (unsigned long)&memstart_offset_seed + - sizeof(memstart_offset_seed)); - return offset; }
Some early boot code runs before the virtual placement of the kernel is finalized, and we used to go back to the very start and recreate the ID map along with the page tables describing the virtual kernel mapping, and this involved setting some global variables with the caches off. In order to ensure that global state created by the KASLR code is not corrupted by the cache invalidation that occurs in that case, we needed to clean those global variables to the PoC explicitly. This is no longer needed now that the ID map is created only once (and the associated global variable updates are no longer repeated). So drop the cache maintenance that is no longer necessary. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/kernel/kaslr.c | 11 ----------- 1 file changed, 11 deletions(-)