@@ -13,11 +13,11 @@
*/
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
.macro __uaccess_ttbr0_disable, tmp1
- mrs \tmp1, ttbr1_el1 // swapper_pg_dir
- add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir
- msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
+ mrs \tmp1, ttbr1_el1 // swapper_pg_dir
+ sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir
+ msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
isb
- sub \tmp1, \tmp1, #SWAPPER_DIR_SIZE
+ add \tmp1, \tmp1, #RESERVED_TTBR0_SIZE
bic \tmp1, \tmp1, #TTBR_ASID_MASK
msr ttbr1_el1, \tmp1 // set reserved ASID
isb
@@ -108,8 +108,8 @@ static inline void __uaccess_ttbr0_disable(void)
unsigned long ttbr;
ttbr = read_sysreg(ttbr1_el1);
- /* reserved_ttbr0 placed at the end of swapper_pg_dir */
- write_sysreg(ttbr + SWAPPER_DIR_SIZE, ttbr0_el1);
+ /* reserved_ttbr0 placed before swapper_pg_dir */
+ write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
isb();
/* Set reserved ASID */
ttbr &= ~TTBR_ASID_MASK;
@@ -218,13 +218,12 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
- swapper_pg_dir = .;
- . += SWAPPER_DIR_SIZE;
-
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
reserved_ttbr0 = .;
. += RESERVED_TTBR0_SIZE;
#endif
+ swapper_pg_dir = .;
+ . += SWAPPER_DIR_SIZE;
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_pg_dir = .;
Currently one resolves the location of the reserved_ttbr0 for PAN by taking a positive offset from swapper_pg_dir. In a future patch we wish to extend the swapper s.t. its size is determined at link time rather than comile time, rendering SWAPPER_DIR_SIZE unsuitable for such a low level calculation. In this patch we re-arrange the order of the linker script s.t. instead one computes reserved_ttbr0 by subtracting RESERVED_TTBR0_SIZE from swapper_pg_dir. Signed-off-by: Steve Capper <steve.capper@arm.com> --- Changed in V3: corrected comment, added Ard's reviewed-by, Rebased on top of kpti Ard, Mark, I removed your tags because I had to add a change for asm-uaccess.h. Please let me know if it's okay for me to put your tags back? Cheers, -- Steve --- arch/arm64/include/asm/asm-uaccess.h | 8 ++++---- arch/arm64/include/asm/uaccess.h | 4 ++-- arch/arm64/kernel/vmlinux.lds.S | 5 ++--- 3 files changed, 8 insertions(+), 9 deletions(-)