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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 <wens@csie.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Chen-Yu Tsai 2016-06-19 12:38:37 +08:00 committed by Hans de Goede
parent 980d6a5511
commit 8c0ef7fad6
1 changed files with 21 additions and 11 deletions
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32
arch/arm/cpu/armv7/psci.S
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@ -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)