From 6cdf9c7ca687e01840d0215437620a20263012fc Mon Sep 17 00:00:00 2001 From: Jungseok Lee Date: Fri, 4 Dec 2015 11:02:25 +0000 Subject: arm64: Store struct thread_info in sp_el0 There is need for figuring out how to manage struct thread_info data when IRQ stack is introduced. struct thread_info information should be copied to IRQ stack under the current thread_info calculation logic whenever context switching is invoked. This is too expensive to keep supporting the approach. Instead, this patch pays attention to sp_el0 which is an unused scratch register in EL1 context. sp_el0 utilization not only simplifies the management, but also prevents text section size from being increased largely due to static allocated IRQ stack as removing masking operation using THREAD_SIZE in many places. Reviewed-by: Catalin Marinas Signed-off-by: Jungseok Lee Signed-off-by: James Morse Signed-off-by: Will Deacon --- arch/arm64/kernel/head.S | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/arm64/kernel/head.S') diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 23cfc08fc8ba..b363f340f2c7 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -424,6 +424,9 @@ __mmap_switched: b 1b 2: adr_l sp, initial_sp, x4 + mov x4, sp + and x4, x4, #~(THREAD_SIZE - 1) + msr sp_el0, x4 // Save thread_info str_l x21, __fdt_pointer, x5 // Save FDT pointer str_l x24, memstart_addr, x6 // Save PHYS_OFFSET mov x29, #0 @@ -606,6 +609,8 @@ ENDPROC(secondary_startup) ENTRY(__secondary_switched) ldr x0, [x21] // get secondary_data.stack mov sp, x0 + and x0, x0, #~(THREAD_SIZE - 1) + msr sp_el0, x0 // save thread_info mov x29, #0 b secondary_start_kernel ENDPROC(__secondary_switched) -- cgit v1.2.3