ARM: suspend: use hash of cpu_logical_map value to index into save array

Currently we hash the MPIDR of the CPU being suspended to determine which
entry in the sleep_save_sp array to use. In some situations, such as when
we want to resume on another physical CPU, the MPIDR of another CPU should
be used instead.

So let's use the value of cpu_logical_map(smp_processor_id()) in place
of the MPIDR in the suspend path.  This will result in the same index
being used as with the previous code unless the caller has modified
cpu_logical_map() beforehand with the MPIDR of the physical CPU the
suspending logical CPU will resume on.

Consequently, if doing a physical CPU migration, cpu_logical_map() must
be updated appropriately somewhere between cpu_pm_enter() and
cpu_suspend().

The register allocation in __cpu_suspend is reworked in order to better
accommodate the additional argument.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>

1 files changed, 11 insertions, 15 deletions

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index db1536b8b30b..622460201911 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -55,6 +55,7 @@
  * specific registers and some other data for resume.
  *  r0 = suspend function arg0
  *  r1 = suspend function
+ *  r2 = MPIDR value the resuming CPU will use
  */
 ENTRY(__cpu_suspend)
         stmfd   sp!, {r4 - r11, lr}
@@ -67,23 +68,18 @@ ENTRY(__cpu_suspend)
         mov     r5, sp                  @ current virtual SP
         add     r4, r4, #12             @ Space for pgd, virt sp, phys resume fn
         sub     sp, sp, r4              @ allocate CPU state on stack
-        stmfd   sp!, {r0, r1}           @ save suspend func arg and pointer
-        add     r0, sp, #8              @ save pointer to save block
-        mov     r1, r4                  @ size of save block
-        mov     r2, r5                  @ virtual SP
         ldr     r3, =sleep_save_sp
+        stmfd   sp!, {r0, r1}           @ save suspend func arg and pointer
         ldr     r3, [r3, #SLEEP_SAVE_SP_VIRT]
-        ALT_SMP(mrc p15, 0, r9, c0, c0, 5)
-        ALT_UP_B(1f)
-        ldr     r8, =mpidr_hash
-        /*
-         * This ldmia relies on the memory layout of the mpidr_hash
-         * struct mpidr_hash.
-         */
-        ldmia   r8, {r4-r7}     @ r4 = mpidr mask (r5,r6,r7) = l[0,1,2] shifts
-        compute_mpidr_hash      lr, r5, r6, r7, r9, r4
-        add     r3, r3, lr, lsl #2
-1:
+        ALT_SMP(ldr r0, =mpidr_hash)
+        ALT_UP_B(1f)
+        /* This ldmia relies on the memory layout of the mpidr_hash struct */
+        ldmia   r0, {r1, r6-r8} @ r1 = mpidr mask (r6,r7,r8) = l[0,1,2] shifts
+        compute_mpidr_hash      r0, r6, r7, r8, r2, r1
+        add     r3, r3, r0, lsl #2
+1:      mov     r2, r5                  @ virtual SP
+        mov     r1, r4                  @ size of save block
+        add     r0, sp, #8              @ pointer to save block
         bl      __cpu_suspend_save
         adr     lr, BSYM(cpu_suspend_abort)
         ldmfd   sp!, {r0, pc}           @ call suspend fn