We recently modified how mmu_enabled works in order to speed spinlocks up (see c33efcf3 and b141dbac). Unfortunately c33efcf3 was a bit hasty in removing mmu_set_enabled. I had forgotten one of the reasons I introduced it was because secondaries don't go through mmu_enable(), they go straight to asm_mmu_enable from secondary_entry. This patch brings it back, albeit renamed to mmu_mark_enabled to match mmu_mark_disabled.
The patch also moves mmu_mark_disabled from psci code to smp code, as psci code shouldn't need to care about mmu stuff, and because we now have a nice balance in the smp code - we mark the mmu disabled for the secondary before we kick it, and then mark it enabled on the init. Finally, a bit unrelated, I've added a lengthy comment to __mmu_enabled in order to warn about what can't be called from there. We need to be cautious there because mmu_enabled() gets scattered around easily, being in basic functions, and thus there's risk of recursion. Signed-off-by: Andrew Jones <[email protected]> Reported-by: Levente Kurusa <[email protected]> --- Couldn't test on arm32, as I usually do, since my board is out to lunch. The issue was found on arm64, a mustang. Testing there shows this patch resolves the issue. It works on tcg too, but it didn't have a problem there in the first place... lib/arm/asm/mmu-api.h | 3 ++- lib/arm/mmu.c | 26 +++++++++++++++++++------- lib/arm/psci.c | 2 -- lib/arm/smp.c | 3 +++ 4 files changed, 24 insertions(+), 10 deletions(-) diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h index f41738be7f9ec..bf0e6a0961416 100644 --- a/lib/arm/asm/mmu-api.h +++ b/lib/arm/asm/mmu-api.h @@ -7,8 +7,9 @@ static inline bool mmu_enabled(void) { return mmu_disabled_cpu_count == 0 || __mmu_enabled(); } -extern void mmu_enable(pgd_t *pgtable); +extern void mmu_mark_enabled(int cpu); extern void mmu_mark_disabled(int cpu); +extern void mmu_enable(pgd_t *pgtable); extern void mmu_disable(void); extern void mmu_enable_idmap(void); extern void mmu_init_io_sect(pgd_t *pgtable, unsigned long virt_offset); diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c index a74d70cb56908..1b7e4fb3cd47e 100644 --- a/lib/arm/mmu.c +++ b/lib/arm/mmu.c @@ -22,17 +22,18 @@ bool __mmu_enabled(void) { int cpu = current_thread_info()->cpu; + /* + * mmu_enabled is called from places that are guarding the + * use of exclusive ops (which require the mmu to be enabled). + * That means we CANNOT call anything from here that may use a + * spinlock, atomic bitop, etc., otherwise we'll recurse. + * [cpumask_]test_bit is safe though. + */ return !cpumask_test_cpu(cpu, &mmu_disabled_cpumask); } -extern void asm_mmu_enable(phys_addr_t pgtable); -void mmu_enable(pgd_t *pgtable) +void mmu_mark_enabled(int cpu) { - int cpu = current_thread_info()->cpu; - - asm_mmu_enable(__pa(pgtable)); - flush_tlb_all(); - if (cpumask_test_and_clear_cpu(cpu, &mmu_disabled_cpumask)) --mmu_disabled_cpu_count; } @@ -43,6 +44,17 @@ void mmu_mark_disabled(int cpu) ++mmu_disabled_cpu_count; } +extern void asm_mmu_enable(phys_addr_t pgtable); +void mmu_enable(pgd_t *pgtable) +{ + int cpu = current_thread_info()->cpu; + + asm_mmu_enable(__pa(pgtable)); + flush_tlb_all(); + + mmu_mark_enabled(cpu); +} + extern void asm_mmu_disable(void); void mmu_disable(void) { diff --git a/lib/arm/psci.c b/lib/arm/psci.c index c4469c9ea1baa..aca88851171f5 100644 --- a/lib/arm/psci.c +++ b/lib/arm/psci.c @@ -9,7 +9,6 @@ #include <asm/psci.h> #include <asm/setup.h> #include <asm/page.h> -#include <asm/mmu-api.h> #define T PSCI_INVOKE_ARG_TYPE __attribute__((noinline)) @@ -30,7 +29,6 @@ int psci_cpu_on(unsigned long cpuid, unsigned long entry_point) extern void secondary_entry(void); int cpu_psci_cpu_boot(unsigned int cpu) { - mmu_mark_disabled(cpu); int err = psci_cpu_on(cpus[cpu], __pa(secondary_entry)); if (err) printf("failed to boot CPU%d (%d)\n", cpu, err); diff --git a/lib/arm/smp.c b/lib/arm/smp.c index ca435dcd5f4a2..3cfc6d5ddedd0 100644 --- a/lib/arm/smp.c +++ b/lib/arm/smp.c @@ -9,6 +9,7 @@ #include <alloc.h> #include <asm/thread_info.h> #include <asm/cpumask.h> +#include <asm/barrier.h> #include <asm/mmu.h> #include <asm/psci.h> #include <asm/smp.h> @@ -23,6 +24,7 @@ secondary_entry_fn secondary_cinit(void) secondary_entry_fn entry; thread_info_init(ti, 0); + mmu_mark_enabled(ti->cpu); /* * Save secondary_data.entry locally to avoid opening a race @@ -45,6 +47,7 @@ void smp_boot_secondary(int cpu, secondary_entry_fn entry) secondary_data.stack = stack_base + THREAD_START_SP; secondary_data.entry = entry; + mmu_mark_disabled(cpu); assert(cpu_psci_cpu_boot(cpu) == 0); while (!cpu_online(cpu)) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
