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linux-sg2042
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riscv: add STRICT_KERNEL_RWX support 

The commit contains that make text section as non-writable, rodata
section as read-only, and data section as non-executable.

The init section should be changed to non-executable.

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Zong Li 2020-03-10 00:55:41 +08:00 committed by Palmer Dabbelt
parent 00cb41d5ad
commit d27c3c9081
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GPG Key ID: 2E1319F35FBB1889
3 changed files with 53 additions and 0 deletions
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1
arch/riscv/Kconfig
View File

@ -61,6 +61,7 @@ config RISCV
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
select SPARSEMEM_STATIC if 32BIT
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU

8
arch/riscv/include/asm/set_memory.h
View File

@ -22,6 +22,14 @@ static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
#endif
#ifdef CONFIG_STRICT_KERNEL_RWX
void set_kernel_text_ro(void);
void set_kernel_text_rw(void);
#else
static inline void set_kernel_text_ro(void) { }
static inline void set_kernel_text_rw(void) { }
#endif
int set_direct_map_invalid_noflush(struct page *page);
int set_direct_map_default_noflush(struct page *page);

44
arch/riscv/mm/init.c
View File

@ -12,6 +12,7 @@
#include <linux/sizes.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
#include <linux/set_memory.h>
#include <asm/fixmap.h>
#include <asm/tlbflush.h>
@ -477,6 +478,17 @@ static void __init setup_vm_final(void)
csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
local_flush_tlb_all();
}
void free_initmem(void)
{
unsigned long init_begin = (unsigned long)__init_begin;
unsigned long init_end = (unsigned long)__init_end;
/* Make the region as non-execuatble. */
set_memory_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
free_initmem_default(POISON_FREE_INITMEM);
}
#else
asmlinkage void __init setup_vm(uintptr_t dtb_pa)
{
@ -488,6 +500,38 @@ static inline void setup_vm_final(void)
}
#endif /* CONFIG_MMU */
#ifdef CONFIG_STRICT_KERNEL_RWX
void set_kernel_text_rw(void)
{
unsigned long text_start = (unsigned long)_text;
unsigned long text_end = (unsigned long)_etext;
set_memory_rw(text_start, (text_end - text_start) >> PAGE_SHIFT);
}
void set_kernel_text_ro(void)
{
unsigned long text_start = (unsigned long)_text;
unsigned long text_end = (unsigned long)_etext;
set_memory_ro(text_start, (text_end - text_start) >> PAGE_SHIFT);
}
void mark_rodata_ro(void)
{
unsigned long text_start = (unsigned long)_text;
unsigned long text_end = (unsigned long)_etext;
unsigned long rodata_start = (unsigned long)__start_rodata;
unsigned long data_start = (unsigned long)_data;
unsigned long max_low = (unsigned long)(__va(PFN_PHYS(max_low_pfn)));
set_memory_ro(text_start, (text_end - text_start) >> PAGE_SHIFT);
set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
set_memory_nx(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
set_memory_nx(data_start, (max_low - data_start) >> PAGE_SHIFT);
}
#endif
void __init paging_init(void)
{
setup_vm_final();