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>

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index db1536b..6224602 100644 (file)
--- 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

diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
index 41cf3cb..2835d35 100644 (file)
--- a/arch/arm/kernel/suspend.c
+++ b/arch/arm/kernel/suspend.c
@@ -10,7 +10,7 @@
 #include <asm/suspend.h>
 #include <asm/tlbflush.h>
 
-extern int __cpu_suspend(unsigned long, int (*)(unsigned long));
+extern int __cpu_suspend(unsigned long, int (*)(unsigned long), u32 cpuid);
 extern void cpu_resume_mmu(void);
 
 #ifdef CONFIG_MMU
@@ -21,6 +21,7 @@ extern void cpu_resume_mmu(void);
 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
 {
        struct mm_struct *mm = current->active_mm;
+       u32 __mpidr = cpu_logical_map(smp_processor_id());
        int ret;
 
        if (!idmap_pgd)
@@ -32,7 +33,7 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
         * resume (indicated by a zero return code), we need to switch
         * back to the correct page tables.
         */
-       ret = __cpu_suspend(arg, fn);
+       ret = __cpu_suspend(arg, fn, __mpidr);
        if (ret == 0) {
                cpu_switch_mm(mm->pgd, mm);
                local_flush_bp_all();
@@ -44,7 +45,8 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
 #else
 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
 {
-       return __cpu_suspend(arg, fn);
+       u32 __mpidr = cpu_logical_map(smp_processor_id());
+       return __cpu_suspend(arg, fn, __mpidr);
 }
 #define        idmap_pgd       NULL
 #endif