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authorHelge Deller <deller@gmx.de>2019-05-10 18:00:01 +0300
committerHelge Deller <deller@gmx.de>2019-05-10 22:00:44 +0300
commit8d0e051cc75e2b1a7e2fd51fc56af332c9619618 (patch)
treeccf08363081a35a3cd8fb4ada4b62cc5fefb1840 /arch/parisc/mm/init.c
parente6eb5fe9123f05dcbf339ae5c0b6d32fcc0685d5 (diff)
downloadlinux-8d0e051cc75e2b1a7e2fd51fc56af332c9619618.tar.xz
parisc: Enable the ro_after_init feature
This patch modifies the initial page mapping functions in the following way: During bootup the init, text and data pages will be mapped RWX and if supported, with huge pages. At final stage of the bootup, the kernel calls free_initmem() and then all pages will be remapped either R-X (for text and read-only data) or RW- (for data). The __init pages will be dropped. This reflects the behaviour of the x86 platform. Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/mm/init.c')
-rw-r--r--arch/parisc/mm/init.c67
1 files changed, 35 insertions, 32 deletions
diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index 3b0f9eab7f2c..b99bcbf1ecdb 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -345,16 +345,7 @@ static void __init setup_bootmem(void)
memblock_dump_all();
}
-static int __init parisc_text_address(unsigned long vaddr)
-{
- static unsigned long head_ptr __initdata;
-
- if (!head_ptr)
- head_ptr = PAGE_MASK & (unsigned long)
- dereference_function_descriptor(&parisc_kernel_start);
-
- return core_kernel_text(vaddr) || vaddr == head_ptr;
-}
+static bool kernel_set_to_readonly;
static void __init map_pages(unsigned long start_vaddr,
unsigned long start_paddr, unsigned long size,
@@ -372,10 +363,11 @@ static void __init map_pages(unsigned long start_vaddr,
unsigned long vaddr;
unsigned long ro_start;
unsigned long ro_end;
- unsigned long kernel_end;
+ unsigned long kernel_start, kernel_end;
ro_start = __pa((unsigned long)_text);
ro_end = __pa((unsigned long)&data_start);
+ kernel_start = __pa((unsigned long)&__init_begin);
kernel_end = __pa((unsigned long)&_end);
end_paddr = start_paddr + size;
@@ -438,26 +430,30 @@ static void __init map_pages(unsigned long start_vaddr,
pg_table = (pte_t *) __va(pg_table) + start_pte;
for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++, pg_table++) {
pte_t pte;
-
- if (force)
- pte = __mk_pte(address, pgprot);
- else if (parisc_text_address(vaddr)) {
- pte = __mk_pte(address, PAGE_KERNEL_EXEC);
- if (address >= ro_start && address < kernel_end)
- pte = pte_mkhuge(pte);
+ pgprot_t prot;
+ bool huge = false;
+
+ if (force) {
+ prot = pgprot;
+ } else if (address < kernel_start || address >= kernel_end) {
+ /* outside kernel memory */
+ prot = PAGE_KERNEL;
+ } else if (!kernel_set_to_readonly) {
+ /* still initializing, allow writing to RO memory */
+ prot = PAGE_KERNEL_RWX;
+ huge = true;
+ } else if (address >= ro_start) {
+ /* Code (ro) and Data areas */
+ prot = (address < ro_end) ?
+ PAGE_KERNEL_EXEC : PAGE_KERNEL;
+ huge = true;
+ } else {
+ prot = PAGE_KERNEL;
}
- else
-#if defined(CONFIG_PARISC_PAGE_SIZE_4KB)
- if (address >= ro_start && address < ro_end) {
- pte = __mk_pte(address, PAGE_KERNEL_EXEC);
+
+ pte = __mk_pte(address, prot);
+ if (huge)
pte = pte_mkhuge(pte);
- } else
-#endif
- {
- pte = __mk_pte(address, pgprot);
- if (address >= ro_start && address < kernel_end)
- pte = pte_mkhuge(pte);
- }
if (address >= end_paddr)
break;
@@ -493,6 +489,12 @@ void __ref free_initmem(void)
{
unsigned long init_begin = (unsigned long)__init_begin;
unsigned long init_end = (unsigned long)__init_end;
+ unsigned long kernel_end = (unsigned long)&_end;
+
+ /* Remap kernel text and data, but do not touch init section yet. */
+ kernel_set_to_readonly = true;
+ map_pages(init_end, __pa(init_end), kernel_end - init_end,
+ PAGE_KERNEL, 0);
/* The init text pages are marked R-X. We have to
* flush the icache and mark them RW-
@@ -509,7 +511,7 @@ void __ref free_initmem(void)
PAGE_KERNEL, 1);
/* force the kernel to see the new TLB entries */
- __flush_tlb_range(0, init_begin, init_end);
+ __flush_tlb_range(0, init_begin, kernel_end);
/* finally dump all the instructions which were cached, since the
* pages are no-longer executable */
@@ -527,8 +529,9 @@ void mark_rodata_ro(void)
{
/* rodata memory was already mapped with KERNEL_RO access rights by
pagetable_init() and map_pages(). No need to do additional stuff here */
- printk (KERN_INFO "Write protecting the kernel read-only data: %luk\n",
- (unsigned long)(__end_rodata - __start_rodata) >> 10);
+ unsigned long roai_size = __end_ro_after_init - __start_ro_after_init;
+
+ pr_info("Write protected read-only-after-init data: %luk\n", roai_size >> 10);
}
#endif