From 8c0ef7fad676827125ad91060361d05ab4b16f44 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Sun, 19 Jun 2016 12:38:37 +0800 Subject: ARM: PSCI: Allocate PSCI stack in secure stack section Now that we have a secure stack section that guarantees usable memory, allocate the PSCI stacks in that section. Also add a diagram detailing how the stacks are placed in memory. Reserved space for the target PC remains unchanged. This should be moved to global variables within a secure data section in the future. Signed-off-by: Chen-Yu Tsai Signed-off-by: Hans de Goede diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S index 46fcf77..bfc4475 100644 --- a/arch/arm/cpu/armv7/psci.S +++ b/arch/arm/cpu/armv7/psci.S @@ -196,18 +196,28 @@ ENTRY(psci_cpu_off_common) bx lr ENDPROC(psci_cpu_off_common) -@ expects CPU ID in r0 and returns stack top in r0 +@ The stacks are allocated in reverse order, i.e. +@ the stack for CPU0 has the highest memory address. +@ +@ -------------------- __secure_stack_end +@ | CPU0 target PC | +@ |------------------| +@ | | +@ | CPU0 stack | +@ | | +@ |------------------| __secure_stack_end - 1KB +@ | . | +@ | . | +@ | . | +@ | . | +@ -------------------- __secure_stack_start +@ +@ This expects CPU ID in r0 and returns stack top in r0 ENTRY(psci_get_cpu_stack_top) - mov r3, #0x400 @ 1kB of stack per CPU - mul r0, r0, r3 - - ldr r3, =psci_text_end @ end of monitor text - add r3, r3, #0x2000 @ Skip two pages - lsr r3, r3, #12 @ Align to start of page - lsl r3, r3, #12 - sub r3, r3, #4 @ reserve 1 word for target PC - sub r0, r3, r0 @ here's our stack! - + @ stack top = __secure_stack_end - (cpuid << ARM_PSCI_STACK_SHIFT) + ldr r3, =__secure_stack_end + sub r0, r3, r0, LSL #ARM_PSCI_STACK_SHIFT + sub r0, r0, #4 @ Save space for target PC bx lr ENDPROC(psci_get_cpu_stack_top) -- cgit v0.10.2