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Merge branch 'riscv-wx-mappings' into for-next

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This contains both the short-term fix for the W+X boot mappings and the
larger cleanup.

* riscv-wx-mappings:
  riscv: Map the kernel with correct permissions the first time
  riscv: Introduce set_kernel_memory helper
  riscv: Simplify xip and !xip kernel address conversion macros
  riscv: Remove CONFIG_PHYS_RAM_BASE_FIXED
  riscv: mm: Fix W+X mappings at boot
This commit is contained in:
Palmer Dabbelt 2021-06-30 21:50:32 -07:00
commit 01112e5e20
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GPG Key ID: 2E1319F35FBB1889
7 changed files with 102 additions and 94 deletions
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6
arch/riscv/Kconfig
View File

@ -494,13 +494,8 @@ config STACKPROTECTOR_PER_TASK
def_bool y
depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
config PHYS_RAM_BASE_FIXED
bool "Explicitly specified physical RAM address"
default n
config PHYS_RAM_BASE
hex "Platform Physical RAM address"
depends on PHYS_RAM_BASE_FIXED
default "0x80000000"
help
This is the physical address of RAM in the system. It has to be
@ -513,7 +508,6 @@ config XIP_KERNEL
# This prevents XIP from being enabled by all{yes,mod}config, which
# fail to build since XIP doesn't support large kernels.
depends on !COMPILE_TEST
select PHYS_RAM_BASE_FIXED
help
Execute-In-Place allows the kernel to run from non-volatile storage
directly addressable by the CPU, such as NOR flash. This saves RAM

27
arch/riscv/include/asm/page.h
View File

@ -83,55 +83,58 @@ extern unsigned long va_pa_offset;
#ifdef CONFIG_64BIT
extern unsigned long va_kernel_pa_offset;
#endif
#ifdef CONFIG_XIP_KERNEL
extern unsigned long va_kernel_xip_pa_offset;
#endif
extern unsigned long pfn_base;
extern uintptr_t load_sz;
#define ARCH_PFN_OFFSET (pfn_base)
#else
#define va_pa_offset 0
#ifdef CONFIG_64BIT
#define va_kernel_pa_offset 0
#endif
#define va_kernel_xip_pa_offset 0
#define ARCH_PFN_OFFSET (PAGE_OFFSET >> PAGE_SHIFT)
#endif /* CONFIG_MMU */
extern unsigned long kernel_virt_addr;
#ifdef CONFIG_64BIT
#define is_kernel_mapping(x) \
((x) >= kernel_virt_addr && (x) < (kernel_virt_addr + load_sz))
#define is_linear_mapping(x) \
((x) >= PAGE_OFFSET && (x) < kernel_virt_addr)
#define linear_mapping_pa_to_va(x) ((void *)((unsigned long)(x) + va_pa_offset))
#ifdef CONFIG_XIP_KERNEL
#define kernel_mapping_pa_to_va(y) ({ \
unsigned long _y = y; \
(_y >= CONFIG_PHYS_RAM_BASE) ? \
(void *)((unsigned long)(_y) + va_kernel_pa_offset + XIP_OFFSET) : \
(void *)((unsigned long)(_y) + va_kernel_xip_pa_offset); \
})
#else
#define kernel_mapping_pa_to_va(x) ((void *)((unsigned long)(x) + va_kernel_pa_offset))
#endif
#define __pa_to_va_nodebug(x) linear_mapping_pa_to_va(x)
#define linear_mapping_va_to_pa(x) ((unsigned long)(x) - va_pa_offset)
#ifdef CONFIG_XIP_KERNEL
#define kernel_mapping_va_to_pa(y) ({ \
unsigned long _y = y; \
(_y < kernel_virt_addr + XIP_OFFSET) ? \
((unsigned long)(_y) - va_kernel_xip_pa_offset) : \
((unsigned long)(_y) - va_kernel_pa_offset - XIP_OFFSET); \
})
#else
#define kernel_mapping_va_to_pa(x) ((unsigned long)(x) - va_kernel_pa_offset)
#endif
#define __va_to_pa_nodebug(x) ({ \
unsigned long _x = x; \
(_x < kernel_virt_addr) ? \
is_linear_mapping(_x) ? \
linear_mapping_va_to_pa(_x) : kernel_mapping_va_to_pa(_x); \
})
#else
#define is_kernel_mapping(x) \
((x) >= kernel_virt_addr && (x) < (kernel_virt_addr + load_sz))
#define is_linear_mapping(x) \
((x) >= PAGE_OFFSET)
#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
#endif /* CONFIG_64BIT */
#ifdef CONFIG_DEBUG_VIRTUAL
extern phys_addr_t __virt_to_phys(unsigned long x);

2
arch/riscv/include/asm/pgtable.h
View File

@ -77,6 +77,8 @@
#ifdef CONFIG_XIP_KERNEL
#define XIP_OFFSET SZ_8M
#else
#define XIP_OFFSET 0
#endif
#ifndef __ASSEMBLY__

17
arch/riscv/include/asm/sections.h
View File

@ -6,6 +6,7 @@
#define __ASM_SECTIONS_H
#include <asm-generic/sections.h>
#include <linux/mm.h>
extern char _start[];
extern char _start_kernel[];
@ -13,4 +14,20 @@ extern char __init_data_begin[], __init_data_end[];
extern char __init_text_begin[], __init_text_end[];
extern char __alt_start[], __alt_end[];
static inline bool is_va_kernel_text(uintptr_t va)
{
uintptr_t start = (uintptr_t)_start;
uintptr_t end = (uintptr_t)__init_data_begin;
return va >= start && va < end;
}
static inline bool is_va_kernel_lm_alias_text(uintptr_t va)
{
uintptr_t start = (uintptr_t)lm_alias(_start);
uintptr_t end = (uintptr_t)lm_alias(__init_data_begin);
return va >= start && va < end;
}
#endif /* __ASM_SECTIONS_H */

24
arch/riscv/include/asm/set_memory.h
View File

@ -16,20 +16,28 @@ int set_memory_rw(unsigned long addr, int numpages);
int set_memory_x(unsigned long addr, int numpages);
int set_memory_nx(unsigned long addr, int numpages);
int set_memory_rw_nx(unsigned long addr, int numpages);
void protect_kernel_text_data(void);
static __always_inline int set_kernel_memory(char *startp, char *endp,
int (*set_memory)(unsigned long start,
int num_pages))
{
unsigned long start = (unsigned long)startp;
unsigned long end = (unsigned long)endp;
int num_pages = PAGE_ALIGN(end - start) >> PAGE_SHIFT;
return set_memory(start, num_pages);
}
#else
static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
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; }
static inline void protect_kernel_text_data(void) {}
static inline int set_memory_rw_nx(unsigned long addr, int numpages) { return 0; }
#endif
#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
void __init protect_kernel_linear_mapping_text_rodata(void);
#else
static inline void protect_kernel_linear_mapping_text_rodata(void) {}
static inline int set_kernel_memory(char *startp, char *endp,
int (*set_memory)(unsigned long start,
int num_pages))
{
return 0;
}
#endif
int set_direct_map_invalid_noflush(struct page *page);

12
arch/riscv/kernel/setup.c
View File

@ -289,11 +289,6 @@ void __init setup_arch(char **cmdline_p)
init_resources();
sbi_init();
if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
protect_kernel_text_data();
protect_kernel_linear_mapping_text_rodata();
}
#ifdef CONFIG_KASAN
kasan_init();
#endif
@ -328,11 +323,10 @@ subsys_initcall(topology_init);
void free_initmem(void)
{
unsigned long init_begin = (unsigned long)__init_begin;
unsigned long init_end = (unsigned long)__init_end;
if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
set_memory_rw_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end),
IS_ENABLED(CONFIG_64BIT) ?
set_memory_rw : set_memory_rw_nx);
free_initmem_default(POISON_FREE_INITMEM);
}

108
arch/riscv/mm/init.c
View File

@ -455,6 +455,43 @@ asmlinkage void __init __copy_data(void)
}
#endif
#ifdef CONFIG_STRICT_KERNEL_RWX
static __init pgprot_t pgprot_from_va(uintptr_t va)
{
if (is_va_kernel_text(va))
return PAGE_KERNEL_READ_EXEC;
/*
* In 64-bit kernel, the kernel mapping is outside the linear mapping so
* we must protect its linear mapping alias from being executed and
* written.
* And rodata section is marked readonly in mark_rodata_ro.
*/
if (IS_ENABLED(CONFIG_64BIT) && is_va_kernel_lm_alias_text(va))
return PAGE_KERNEL_READ;
return PAGE_KERNEL;
}
void mark_rodata_ro(void)
{
set_kernel_memory(__start_rodata, _data, set_memory_ro);
if (IS_ENABLED(CONFIG_64BIT))
set_kernel_memory(lm_alias(__start_rodata), lm_alias(_data),
set_memory_ro);
debug_checkwx();
}
#else
static __init pgprot_t pgprot_from_va(uintptr_t va)
{
if (IS_ENABLED(CONFIG_64BIT) && !is_kernel_mapping(va))
return PAGE_KERNEL;
return PAGE_KERNEL_EXEC;
}
#endif /* CONFIG_STRICT_KERNEL_RWX */
/*
* setup_vm() is called from head.S with MMU-off.
*
@ -474,7 +511,7 @@ asmlinkage void __init __copy_data(void)
#endif
static uintptr_t load_pa __initdata;
static uintptr_t load_sz __initdata;
uintptr_t load_sz;
#ifdef CONFIG_XIP_KERNEL
#define load_pa (*((uintptr_t *)XIP_FIXUP(&load_pa)))
#define load_sz (*((uintptr_t *)XIP_FIXUP(&load_sz)))
@ -486,7 +523,8 @@ static uintptr_t xiprom_sz __initdata;
#define xiprom_sz (*((uintptr_t *)XIP_FIXUP(&xiprom_sz)))
#define xiprom (*((uintptr_t *)XIP_FIXUP(&xiprom)))
static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size,
__always_unused bool early)
{
uintptr_t va, end_va;
@ -505,7 +543,8 @@ static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
map_size, PAGE_KERNEL);
}
#else
static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size,
bool early)
{
uintptr_t va, end_va;
@ -513,7 +552,9 @@ static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
for (va = kernel_virt_addr; va < end_va; va += map_size)
create_pgd_mapping(pgdir, va,
load_pa + (va - kernel_virt_addr),
map_size, PAGE_KERNEL_EXEC);
map_size,
early ?
PAGE_KERNEL_EXEC : pgprot_from_va(va));
}
#endif
@ -590,7 +631,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
* us to reach paging_init(). We map all memory banks later
* in setup_vm_final() below.
*/
create_kernel_page_table(early_pg_dir, map_size);
create_kernel_page_table(early_pg_dir, map_size, true);
#ifndef __PAGETABLE_PMD_FOLDED
/* Setup early PMD for DTB */
@ -666,22 +707,6 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
#endif
}
#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
void __init protect_kernel_linear_mapping_text_rodata(void)
{
unsigned long text_start = (unsigned long)lm_alias(_start);
unsigned long init_text_start = (unsigned long)lm_alias(__init_text_begin);
unsigned long rodata_start = (unsigned long)lm_alias(__start_rodata);
unsigned long data_start = (unsigned long)lm_alias(_data);
set_memory_ro(text_start, (init_text_start - text_start) >> PAGE_SHIFT);
set_memory_nx(text_start, (init_text_start - 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);
}
#endif
static void __init setup_vm_final(void)
{
uintptr_t va, map_size;
@ -714,21 +739,15 @@ 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);
create_pgd_mapping(swapper_pg_dir, va, pa,
map_size,
#ifdef CONFIG_64BIT
PAGE_KERNEL
#else
PAGE_KERNEL_EXEC
#endif
);
create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
pgprot_from_va(va));
}
}
#ifdef CONFIG_64BIT
/* Map the kernel */
create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
create_kernel_page_table(swapper_pg_dir, PMD_SIZE, false);
#endif
/* Clear fixmap PTE and PMD mappings */
@ -759,35 +778,6 @@ static inline void setup_vm_final(void)
}
#endif /* CONFIG_MMU */
#ifdef CONFIG_STRICT_KERNEL_RWX
void __init protect_kernel_text_data(void)
{
unsigned long text_start = (unsigned long)_start;
unsigned long init_text_start = (unsigned long)__init_text_begin;
unsigned long init_data_start = (unsigned long)__init_data_begin;
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, (init_text_start - text_start) >> PAGE_SHIFT);
set_memory_ro(init_text_start, (init_data_start - init_text_start) >> PAGE_SHIFT);
set_memory_nx(init_data_start, (rodata_start - init_data_start) >> PAGE_SHIFT);
/* rodata section is marked readonly in mark_rodata_ro */
set_memory_nx(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
set_memory_nx(data_start, (max_low - data_start) >> PAGE_SHIFT);
}
void mark_rodata_ro(void)
{
unsigned long rodata_start = (unsigned long)__start_rodata;
unsigned long data_start = (unsigned long)_data;
set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
debug_checkwx();
}
#endif
#ifdef CONFIG_KEXEC_CORE
/*
* reserve_crashkernel() - reserves memory for crash kernel