Re: [PATCH] riscv: Fix 32b kernel caused by 64b kernel mapping moving outside linear mapping

Alex Ghiti <alex@xxxxxxxx> · Fri, 23 Apr 2021 04:34:02 -0400

Le 4/20/21 à 12:18 AM, Anup Patel a écrit :
On Sat, Apr 17, 2021 at 10:52 PM Alexandre Ghiti <alex@xxxxxxxx> wrote:

Fix multiple leftovers when moving the kernel mapping outside the linear
mapping for 64b kernel that left the 32b kernel unusable.

Fixes: 4b67f48da707 ("riscv: Move kernel mapping outside of linear mapping")
Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>

Quite a few #ifdef but I don't see any better way at the moment. Maybe we can
clean this later. Otherwise looks good to me.

Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>

Thanks Anup!

@Palmer: This is not on for-next yet and then rv32 is broken. This does 
not apply immediately on top of for-next though, so if you need a new 
version, I can do that. But this squashes nicely with the patch it fixes 
if you prefer.

Let me know, I can do that very quickly.

Alex


Regards,
Anup

---
  arch/riscv/include/asm/page.h    |  9 +++++++++
  arch/riscv/include/asm/pgtable.h | 16 ++++++++++++----
  arch/riscv/mm/init.c             | 25 ++++++++++++++++++++++++-
  3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 22cfb2be60dc..f64b61296c0c 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -90,15 +90,20 @@ typedef struct page *pgtable_t;

  #ifdef CONFIG_MMU
  extern unsigned long va_pa_offset;
+#ifdef CONFIG_64BIT
  extern unsigned long va_kernel_pa_offset;
+#endif
  extern unsigned long pfn_base;
  #define ARCH_PFN_OFFSET                (pfn_base)
  #else
  #define va_pa_offset           0
+#ifdef CONFIG_64BIT
  #define va_kernel_pa_offset    0
+#endif
  #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
  #endif /* CONFIG_MMU */

+#ifdef CONFIG_64BIT
  extern unsigned long kernel_virt_addr;

  #define linear_mapping_pa_to_va(x)     ((void *)((unsigned long)(x) + va_pa_offset))
@@ -112,6 +117,10 @@ extern unsigned long kernel_virt_addr;
         (_x < kernel_virt_addr) ?                                               \
                 linear_mapping_va_to_pa(_x) : kernel_mapping_va_to_pa(_x);      \
         })
+#else
+#define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
+#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
+#endif

  #ifdef CONFIG_DEBUG_VIRTUAL
  extern phys_addr_t __virt_to_phys(unsigned long x);
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 80e63a93e903..5afda75cc2c3 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -16,19 +16,27 @@
  #else

  #define ADDRESS_SPACE_END      (UL(-1))
-/*
- * Leave 2GB for kernel and BPF at the end of the address space
- */
+
+#ifdef CONFIG_64BIT
+/* Leave 2GB for kernel and BPF at the end of the address space */
  #define KERNEL_LINK_ADDR       (ADDRESS_SPACE_END - SZ_2G + 1)
+#else
+#define KERNEL_LINK_ADDR       PAGE_OFFSET
+#endif

  #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
  #define VMALLOC_END      (PAGE_OFFSET - 1)
  #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)

-/* KASLR should leave at least 128MB for BPF after the kernel */
  #define BPF_JIT_REGION_SIZE    (SZ_128M)
+#ifdef CONFIG_64BIT
+/* KASLR should leave at least 128MB for BPF after the kernel */
  #define BPF_JIT_REGION_START   PFN_ALIGN((unsigned long)&_end)
  #define BPF_JIT_REGION_END     (BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE)
+#else
+#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
+#define BPF_JIT_REGION_END     (VMALLOC_END)
+#endif

  /* Modules always live before the kernel */
  #ifdef CONFIG_64BIT
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 093f3a96ecfc..dc9b988e0778 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -91,8 +91,10 @@ static void print_vm_layout(void)
                   (unsigned long)VMALLOC_END);
         print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
                   (unsigned long)high_memory);
+#ifdef CONFIG_64BIT
         print_mlm("kernel", (unsigned long)KERNEL_LINK_ADDR,
                   (unsigned long)ADDRESS_SPACE_END);
+#endif
  }
  #else
  static void print_vm_layout(void) { }
@@ -165,9 +167,11 @@ static struct pt_alloc_ops pt_ops;
  /* Offset between linear mapping virtual address and kernel load address */
  unsigned long va_pa_offset;
  EXPORT_SYMBOL(va_pa_offset);
+#ifdef CONFIG_64BIT
  /* Offset between kernel mapping virtual address and kernel load address */
  unsigned long va_kernel_pa_offset;
  EXPORT_SYMBOL(va_kernel_pa_offset);
+#endif
  unsigned long pfn_base;
  EXPORT_SYMBOL(pfn_base);

@@ -410,7 +414,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
         load_sz = (uintptr_t)(&_end) - load_pa;

         va_pa_offset = PAGE_OFFSET - load_pa;
+#ifdef CONFIG_64BIT
         va_kernel_pa_offset = kernel_virt_addr - load_pa;
+#endif

         pfn_base = PFN_DOWN(load_pa);

@@ -469,12 +475,16 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
                            pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
         dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
  #else /* CONFIG_BUILTIN_DTB */
+#ifdef CONFIG_64BIT
         /*
          * __va can't be used since it would return a linear mapping address
          * whereas dtb_early_va will be used before setup_vm_final installs
          * the linear mapping.
          */
         dtb_early_va = kernel_mapping_pa_to_va(dtb_pa);
+#else
+       dtb_early_va = __va(dtb_pa);
+#endif /* CONFIG_64BIT */
  #endif /* CONFIG_BUILTIN_DTB */
  #else
  #ifndef CONFIG_BUILTIN_DTB
@@ -486,7 +496,11 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
                            pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
         dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1));
  #else /* CONFIG_BUILTIN_DTB */
+#ifdef CONFIG_64BIT
         dtb_early_va = kernel_mapping_pa_to_va(dtb_pa);
+#else
+       dtb_early_va = __va(dtb_pa);
+#endif /* CONFIG_64BIT */
  #endif /* CONFIG_BUILTIN_DTB */
  #endif
         dtb_early_pa = dtb_pa;
@@ -571,12 +585,21 @@ static void __init setup_vm_final(void)
                 for (pa = start; pa < end; pa += map_size) {
                         va = (uintptr_t)__va(pa);
                         create_pgd_mapping(swapper_pg_dir, va, pa,
-                                          map_size, PAGE_KERNEL);
+                                          map_size,
+#ifdef CONFIG_64BIT
+                                          PAGE_KERNEL
+#else
+                                          PAGE_KERNEL_EXEC
+#endif
+                                       );
+
                 }
         }

+#ifdef CONFIG_64BIT
         /* Map the kernel */
         create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
+#endif

         /* Clear fixmap PTE and PMD mappings */
         clear_fixmap(FIX_PTE);
--
2.20.1







