The kernel is now mapped at the end of the address space and it should
be accessed through this mapping only: so map the whole kernel in the
linear mapping as read only.
Signed-off-by: Alexandre Ghiti <a...@ghiti.fr>
---
arch/riscv/include/asm/page.h | 9 ++++++++-
arch/riscv/mm/init.c | 29 +++++++++++++++++++++--------
2 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 98188e315e8d..a93e35aaa717 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -102,8 +102,15 @@ extern unsigned long pfn_base;
extern unsigned long max_low_pfn;
extern unsigned long min_low_pfn;
extern unsigned long kernel_virt_addr;
+extern uintptr_t load_pa, load_sz;
+
+#define linear_mapping_pa_to_va(x) ((void *)((unsigned long)(x) +
va_pa_offset))
+#define kernel_mapping_pa_to_va(x) \
+ ((void *)((unsigned long) (x) + va_kernel_pa_offset))
+#define __pa_to_va_nodebug(x) \
+ ((x >= load_pa && x < load_pa + load_sz) ? \
+ kernel_mapping_pa_to_va(x): linear_mapping_pa_to_va(x))
-#define __pa_to_va_nodebug(x) ((void *)((unsigned long) (x) + va_pa_offset))
#define linear_mapping_va_to_pa(x) ((unsigned long)(x) - va_pa_offset)
#define kernel_mapping_va_to_pa(x) \
((unsigned long)(x) - va_kernel_pa_offset)
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 9d06ff0e015a..7b87c14f1d24 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -159,8 +159,6 @@ void __init setup_bootmem(void)
{
phys_addr_t mem_start = 0;
phys_addr_t start, end = 0;
- phys_addr_t vmlinux_end = __pa_symbol(&_end);
- phys_addr_t vmlinux_start = __pa_symbol(&_start);
u64 i;
/* Find the memory region containing the kernel */
@@ -168,7 +166,7 @@ void __init setup_bootmem(void)
phys_addr_t size = end - start;
if (!mem_start)
mem_start = start;
- if (start <= vmlinux_start && vmlinux_end <= end)
+ if (start <= load_pa && (load_pa + load_sz) <= end)
BUG_ON(size == 0);
}
@@ -179,8 +177,13 @@ void __init setup_bootmem(void)
*/
memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
- /* Reserve from the start of the kernel to the end of the kernel */
- memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
+ /*
+ * Reserve from the start of the kernel to the end of the kernel
+ * and make sure we align the reservation on PMD_SIZE since we will
+ * map the kernel in the linear mapping as read-only: we do not want
+ * any allocation to happen between _end and the next pmd aligned page.
+ */
+ memblock_reserve(load_pa, (load_sz + PMD_SIZE - 1) & ~(PMD_SIZE - 1));
max_pfn = PFN_DOWN(memblock_end_of_DRAM());
max_low_pfn = max_pfn;
@@ -438,7 +441,9 @@ static uintptr_t __init best_map_size(phys_addr_t base,
phys_addr_t size)
#error "setup_vm() is called from head.S before relocate so it should not use
absolute addressing."
#endif
-static uintptr_t load_pa, load_sz;
+uintptr_t load_pa, load_sz;
+EXPORT_SYMBOL(load_pa);
+EXPORT_SYMBOL(load_sz);
static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
{
@@ -596,9 +601,17 @@ static void __init setup_vm_final(void)
map_size = best_map_size(start, end - start);
for (pa = start; pa < end; pa += map_size) {
- va = (uintptr_t)__va(pa);
+ pgprot_t prot = PAGE_KERNEL;
+
+ /* Protect the kernel mapping that lies in the linear
mapping */
+ if (pa >= __pa(_start) && pa < __pa(_end))
+ prot = PAGE_KERNEL_READ;
+
+ /* Make sure we get virtual addresses in the linear
mapping */
+ va = (uintptr_t)linear_mapping_pa_to_va(pa);
+
create_pgd_mapping(swapper_pg_dir, va, pa,
- map_size, PAGE_KERNEL);
+ map_size, prot);
}
}
--
2.20.1
