Unverified Commit d27c3c90 authored by Zong Li's avatar Zong Li Committed by Palmer Dabbelt
Browse files

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: default avatarZong Li <zong.li@sifive.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 00cb41d5

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/riscv/include/asm/set_memory.h

+8 −0
Original line number Diff line number Diff line
@@ -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);

arch/riscv/mm/init.c

+44 −0
Original line number Diff line number Diff line
@@ -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();