On 06/05/2018 02:33 AM, Jun Yao wrote:
Introduce __pa_swapper_pg_dir to save physical address of
swapper_pg_dir. And pass it as an argument to __enable_mmu().

Signed-off-by: Jun Yao <yaojun8558...@gmail.com>
---
  arch/arm64/include/asm/mmu_context.h |  4 +---
  arch/arm64/include/asm/pgtable.h     |  1 +
  arch/arm64/kernel/cpufeature.c       |  2 +-
  arch/arm64/kernel/head.S             |  6 ++++--
  arch/arm64/kernel/hibernate.c        |  2 +-
  arch/arm64/kernel/sleep.S            |  1 +
  arch/arm64/mm/kasan_init.c           |  4 ++--
  arch/arm64/mm/mmu.c                  | 11 +++++++++--
  8 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/mmu_context.h 
b/arch/arm64/include/asm/mmu_context.h
index 39ec0b8a689e..3eddb871f251 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -141,14 +141,12 @@ static inline void cpu_install_idmap(void)
   * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
   * avoiding the possibility of conflicting TLB entries being allocated.
   */
-static inline void cpu_replace_ttbr1(pgd_t *pgdp)
+static inline void cpu_replace_ttbr1(phys_addr_t pgd_phys)
  {
        typedef void (ttbr_replace_func)(phys_addr_t);
        extern ttbr_replace_func idmap_cpu_replace_ttbr1;
        ttbr_replace_func *replace_phys;
- phys_addr_t pgd_phys = virt_to_phys(pgdp);
-
        replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
cpu_install_idmap();
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7c4c8f318ba9..519ab5581b08 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -722,6 +722,7 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
  extern pgd_t swapper_pg_end[];
  extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
  extern pgd_t tramp_pg_dir[PTRS_PER_PGD];
+extern volatile phys_addr_t __pa_swapper_pg_dir;
/*
   * Encode and decode a swap entry:
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d2856b129097..e3d76a9dd67a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -917,7 +917,7 @@ kpti_install_ng_mappings(const struct 
arm64_cpu_capabilities *__unused)
        remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);
cpu_install_idmap();
-       remap_fn(cpu, num_online_cpus(), __pa_symbol(swapper_pg_dir));
+       remap_fn(cpu, num_online_cpus(), __pa_swapper_pg_dir);
        cpu_uninstall_idmap();
if (!cpu)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index b0853069702f..2e871b1cb75f 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -706,6 +706,7 @@ secondary_startup:
         * Common entry point for secondary CPUs.
         */
        bl      __cpu_setup                     // initialise processor
+       ldr_l   x26, __pa_swapper_pg_dir
        bl      __enable_mmu
        ldr     x8, =__secondary_switched
        br      x8
@@ -748,6 +749,7 @@ ENDPROC(__secondary_switched)
   * Enable the MMU.
   *
   *  x0  = SCTLR_EL1 value for turning on the MMU.
+ *  x26 = TTBR1 value for turning on the MMU.
   *
   * Returns to the caller via x30/lr. This requires the caller to be covered
   * by the .idmap.text section.
@@ -762,9 +764,8 @@ ENTRY(__enable_mmu)
        b.ne    __no_granule_support
        update_early_cpu_boot_status 0, x1, x2
        adrp    x1, idmap_pg_dir
-       adrp    x2, swapper_pg_dir
        phys_to_ttbr x3, x1
-       phys_to_ttbr x4, x2
+       phys_to_ttbr x4, x26
        msr     ttbr0_el1, x3                   // load TTBR0
        msr     ttbr1_el1, x4                   // load TTBR1
        isb
@@ -823,6 +824,7 @@ __primary_switch:
        mrs     x20, sctlr_el1                  // preserve old SCTLR_EL1 value
  #endif
+ adrp x26, swapper_pg_dir
        bl      __enable_mmu
  #ifdef CONFIG_RELOCATABLE
        bl      __relocate_kernel
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 6b2686d54411..0a0a0ca19f9b 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -125,7 +125,7 @@ int arch_hibernation_header_save(void *addr, unsigned int 
max_size)
                return -EOVERFLOW;
arch_hdr_invariants(&hdr->invariants);
-       hdr->ttbr1_el1               = __pa_symbol(swapper_pg_dir);
+       hdr->ttbr1_el1          = __pa_swapper_pg_dir;
        hdr->reenter_kernel  = _cpu_resume;
/* We can't use __hyp_get_vectors() because kvm may still be loaded */
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index bebec8ef9372..03854c329449 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -101,6 +101,7 @@ ENTRY(cpu_resume)
        bl      el2_setup               // if in EL2 drop to EL1 cleanly
        bl      __cpu_setup
        /* enable the MMU early - so we can access sleep_save_stash by va */
+       ldr_l   x26, __pa_swapper_pg_dir
        bl      __enable_mmu
        ldr     x8, =_cpu_resume
        br      x8
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 12145874c02b..dd4f28c19165 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -199,7 +199,7 @@ void __init kasan_init(void)
         */
        memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
        dsb(ishst);
-       cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
+       cpu_replace_ttbr1(__pa_symbol(tmp_pg_dir));
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); @@ -236,7 +236,7 @@ void __init kasan_init(void)
                        pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
memset(kasan_zero_page, 0, PAGE_SIZE);
-       cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+       cpu_replace_ttbr1(__pa_swapper_pg_dir);
/* At this point kasan is fully initialized. Enable error messages */
        init_task.kasan_depth = 0;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9f1ec1..c7df2f0d2e85 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -55,6 +55,9 @@ u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
  u64 kimage_voffset __ro_after_init;
  EXPORT_SYMBOL(kimage_voffset);
+volatile phys_addr_t __section(".mmuoff.data.read")
+__pa_swapper_pg_dir;
+
  /*
   * Empty_zero_page is a special page that is used for zero-initialized data
   * and COW.
@@ -631,6 +634,10 @@ void __init paging_init(void)
        phys_addr_t pgd_phys = early_pgtable_alloc();
        pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
+ __pa_swapper_pg_dir = __pa_symbol(swapper_pg_dir);
+       __flush_dcache_area((void *)&__pa_swapper_pg_dir,
+                           sizeof(__pa_swapper_pg_dir));
+

Can you add a comment here explaining why the flush is needed and
also why the variable gets placed in the particular section?
A brief summary of https://www.spinics.net/lists/kernel/msg2819594.html
would be fine.

Thanks,
Laura

        map_kernel(pgdp);
        map_mem(pgdp);
@@ -642,9 +649,9 @@ void __init paging_init(void)
         *
         * To do this we need to go via a temporary pgd.
         */
-       cpu_replace_ttbr1(__va(pgd_phys));
+       cpu_replace_ttbr1(pgd_phys);
        memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
-       cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+       cpu_replace_ttbr1(__pa_swapper_pg_dir);
pgd_clear_fixmap();
        memblock_free(pgd_phys, PAGE_SIZE);


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