Now that linear and IMMR dedicated TLB handling is gone, kernel boundary address comparison is similar in ITLB miss handler and in DTLB miss handler.
Create a macro named compare_to_kernel_boundary. When TASK_SIZE is strictly below 0x80000000 and PAGE_OFFSET is above 0x80000000, it is enough to compare to 0x8000000, and this can be done with a single instruction. Using not. instruction, we get to use 'blt' conditional branch as when doing a regular comparison: 0x00000000 <= addr <= 0x7fffffff ==> 0xffffffff >= NOT(addr) >= 0x80000000 The above test corresponds to a 'blt' Otherwise, do a regular comparison using two instructions. Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu> --- arch/powerpc/kernel/head_8xx.S | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 9f3f7f3d03a7..9a117b9f0998 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -32,10 +32,15 @@ #include "head_32.h" +.macro compare_to_kernel_boundary scratch, addr #if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000 /* By simply checking Address >= 0x80000000, we know if its a kernel address */ -#define SIMPLE_KERNEL_ADDRESS 1 + not. \scratch, \addr +#else + rlwinm \scratch, \addr, 16, 0xfff8 + cmpli cr0, \scratch, PAGE_OFFSET@h #endif +.endm /* * We need an ITLB miss handler for kernel addresses if: @@ -209,20 +214,11 @@ InstructionTLBMiss: mtspr SPRN_MD_EPN, r10 #ifdef ITLB_MISS_KERNEL mfcr r11 -#if defined(SIMPLE_KERNEL_ADDRESS) - cmpi cr0, r10, 0 /* Address >= 0x80000000 */ -#else - rlwinm r10, r10, 16, 0xfff8 - cmpli cr0, r10, PAGE_OFFSET@h -#endif + compare_to_kernel_boundary r10, r10 #endif mfspr r10, SPRN_M_TWB /* Get level 1 table */ #ifdef ITLB_MISS_KERNEL -#if defined(SIMPLE_KERNEL_ADDRESS) - bge+ 3f -#else blt+ 3f -#endif rlwinm r10, r10, 0, 20, 31 oris r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha 3: @@ -288,9 +284,7 @@ DataStoreTLBMiss: * kernel page tables. */ mfspr r10, SPRN_MD_EPN - rlwinm r10, r10, 16, 0xfff8 - cmpli cr0, r10, PAGE_OFFSET@h - + compare_to_kernel_boundary r10, r10 mfspr r10, SPRN_M_TWB /* Get level 1 table */ blt+ 3f rlwinm r10, r10, 0, 20, 31 -- 2.25.0