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arm64: smp: unify task and sp setup

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Once we enable the MMU, we have to initialize:

* SP_EL0 to point at the active task
* SP to point at the active task's stack
* SCS_SP to point at the active task's shadow stack

For all tasks (including init_task), this information can be derived
from the task's task_struct.

Let's unify __primary_switched and __secondary_switched to consistently
acquire this information from the relevant task_struct. At the same
time, let's fold this together with initializing a task's final frame.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210520115031.18509-6-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland
2021-05-20 12:50:30 +01:00
committed by Will Deacon
parent 3305e7f74a
commit 8e334d729b
1 changed files with 15 additions and 18 deletions
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33
arch/arm64/kernel/head.S
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@@ -395,15 +395,24 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
SYM_FUNC_END(__create_page_tables)
/*
* Initialize CPU registers with task-specific and cpu-specific context.
*
* Create a final frame record at task_pt_regs(current)->stackframe, so
* that the unwinder can identify the final frame record of any task by
* its location in the task stack. We reserve the entire pt_regs space
* for consistency with user tasks and kthreads.
*/
.macro setup_final_frame
.macro init_cpu_task tsk, tmp
msr sp_el0, \tsk
ldr \tmp, [\tsk, #TSK_STACK]
add sp, \tmp, #THREAD_SIZE
sub sp, sp, #PT_REGS_SIZE
stp xzr, xzr, [sp, #S_STACKFRAME]
add x29, sp, #S_STACKFRAME
scs_load \tsk, \tmp
.endm
/*
@@ -412,22 +421,16 @@ SYM_FUNC_END(__create_page_tables)
* x0 = __PHYS_OFFSET
*/
SYM_FUNC_START_LOCAL(__primary_switched)
adrp x4, init_thread_union
add sp, x4, #THREAD_SIZE
adr_l x5, init_task
msr sp_el0, x5 // Save thread_info
adr_l x4, init_task
init_cpu_task x4, x5
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
isb
stp xzr, x30, [sp, #-16]!
stp x29, x30, [sp, #-16]!
mov x29, sp
#ifdef CONFIG_SHADOW_CALL_STACK
adr_l scs_sp, init_shadow_call_stack // Set shadow call stack
#endif
str_l x21, __fdt_pointer, x5 // Save FDT pointer
ldr_l x4, kimage_vaddr // Save the offset between
@@ -459,8 +462,7 @@ SYM_FUNC_START_LOCAL(__primary_switched)
0:
#endif
bl switch_to_vhe // Prefer VHE if possible
add sp, sp, #16
setup_final_frame
ldp x29, x30, [sp], #16
bl start_kernel
ASM_BUG()
SYM_FUNC_END(__primary_switched)
@@ -648,12 +650,7 @@ SYM_FUNC_START_LOCAL(__secondary_switched)
ldr x2, [x0, #CPU_BOOT_TASK]
cbz x2, __secondary_too_slow
ldr x1, [x2, #TSK_STACK]
add sp, x1, #THREAD_SIZE
msr sp_el0, x2
scs_load x2, x3
setup_final_frame
init_cpu_task x2, x1
#ifdef CONFIG_ARM64_PTR_AUTH
ptrauth_keys_init_cpu x2, x3, x4, x5