Messages in this thread |  | | Date | Fri, 28 May 2021 21:08:43 -0700 | From | Drew Fustini <> | Subject | Re: [PATCH v2] riscv: Map the kernel with correct permissions the first time |
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On Wed, May 26, 2021 at 03:41:10PM +0200, Alexandre Ghiti wrote: > For 64b kernels, we map all the kernel with write and execute permissions > and afterwards remove writability from text and executability from data. > > For 32b kernels, the kernel mapping resides in the linear mapping, so we > map all the linear mapping as writable and executable and afterwards we > remove those properties for unused memory and kernel mapping as > described above. > > Change this behavior to directly map the kernel with correct permissions > and avoid going through the whole mapping to fix the permissions. > > At the same time, this fixes an issue introduced by commit 2bfc6cd81bd1 > ("riscv: Move kernel mapping outside of linear mapping") as reported > here https://github.com/starfive-tech/linux/issues/17. > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > --- > > Changes in v2: > * Rebased on top of for-next (and "riscv: mm: fix build errors caused by > mk_pmd()") > * Get rid of protect_kernel_linear_mapping_text_rodata as suggested by > Jisheng > * Improve code in general compared to previous RFC > > Tested on: > > * kernel > - rv32: OK > - rv64: OK > > * kernel w/o CONFIG_STRICT_KERNEL_RWX: > - rv32: OK > - rv64: OK > > * xipkernel: > - rv32: build only > - rv64: OK > > * nommukernel: > - rv64: build only > > arch/riscv/include/asm/page.h | 9 +- > arch/riscv/include/asm/sections.h | 16 ++++ > arch/riscv/include/asm/set_memory.h | 8 -- > arch/riscv/kernel/setup.c | 5 -- > arch/riscv/mm/init.c | 123 +++++++++++++++------------- > 5 files changed, 89 insertions(+), 72 deletions(-) > > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h > index 6e004d8fda4d..7ff5e0d81e41 100644 > --- a/arch/riscv/include/asm/page.h > +++ b/arch/riscv/include/asm/page.h > @@ -95,6 +95,7 @@ extern unsigned long va_kernel_pa_offset; > #endif > extern unsigned long va_kernel_xip_pa_offset; > extern unsigned long pfn_base; > +extern uintptr_t load_sz; > #define ARCH_PFN_OFFSET (pfn_base) > #else > #define va_pa_offset 0 > @@ -108,6 +109,9 @@ extern unsigned long pfn_base; > 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)) > #define kernel_mapping_pa_to_va(y) ({ \ > unsigned long _y = y; \ > @@ -127,10 +131,13 @@ extern unsigned long kernel_virt_addr; > > #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 /* CONFIG_64BIT */ > diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h > index 8a303fb1ee3b..6b5affecca83 100644 > --- a/arch/riscv/include/asm/sections.h > +++ b/arch/riscv/include/asm/sections.h > @@ -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 +14,19 @@ 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) > +{ > + return (va >= (uintptr_t)_start && va < (uintptr_t)__init_text_begin); > +} > + > +static inline bool is_va_kernel_lm_alias_text(uintptr_t va) > +{ > + return (va >= (uintptr_t)lm_alias(_start) && va < (uintptr_t)lm_alias(__init_text_begin)); > +} > + > +static inline bool is_va_kernel_init_text(uintptr_t va) > +{ > + return (va >= (uintptr_t)__init_text_begin && va < (uintptr_t)__init_data_begin); > +} > + > #endif /* __ASM_SECTIONS_H */ > diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h > index 086f757e8ba3..ebb8516ec5bc 100644 > --- a/arch/riscv/include/asm/set_memory.h > +++ b/arch/riscv/include/asm/set_memory.h > @@ -16,22 +16,14 @@ 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); > #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 protect_kernel_linear_mapping_text_rodata(void); > -#else > -static inline void protect_kernel_linear_mapping_text_rodata(void) {} > -#endif > - > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_default_noflush(struct page *page); > bool kernel_page_present(struct page *page); > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index 4db4d0b5911f..96f483e7c279 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -290,11 +290,6 @@ 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_SWIOTLB > swiotlb_init(1); > #endif > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 2d80088f33d5..4b1bcbbd50aa 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -425,6 +425,63 @@ asmlinkage void __init __copy_data(void) > } > #endif > > +#ifdef CONFIG_STRICT_KERNEL_RWX > +static __init pgprot_t pgprot_from_va(uintptr_t va) > +{ > +#ifdef CONFIG_64BIT > + if (is_va_kernel_text(va) || is_va_kernel_init_text(va)) > + return PAGE_KERNEL_READ_EXEC; > + > + /* > + * We must mark only text as read-only as init text will get freed later > + * and rodata section is marked readonly in mark_rodata_ro. > + */ > + if (is_va_kernel_lm_alias_text(va)) > + return PAGE_KERNEL_READ; > + > + return PAGE_KERNEL; > +#else > + if (is_va_kernel_text(va)) > + return PAGE_KERNEL_READ_EXEC; > + > + if (is_va_kernel_init_text(va)) > + return PAGE_KERNEL_EXEC; > + > + return PAGE_KERNEL; > +#endif /* CONFIG_64BIT */ > +} > + > +void mark_rodata_ro(void) > +{ > + unsigned long rodata_start = (unsigned long)__start_rodata; > + unsigned long data_start = (unsigned long)_data; > + unsigned long __maybe_unused lm_rodata_start = (unsigned long)lm_alias(__start_rodata); > + unsigned long __maybe_unused lm_data_start = (unsigned long)lm_alias(_data); > + > + set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT); > +#ifdef CONFIG_64BIT > + set_memory_ro(lm_rodata_start, (lm_data_start - lm_rodata_start) >> PAGE_SHIFT); > +#endif > + > + debug_checkwx(); > +} > +#else /* CONFIG_STRICT_KERNEL_RWX */ > +static __init pgprot_t pgprot_from_va(uintptr_t va) > +{ > +#ifdef CONFIG_64BIT > + if (is_kernel_mapping(va)) > + return PAGE_KERNEL_EXEC; > + > + if (is_linear_mapping(va)) > + return PAGE_KERNEL; > + > + return PAGE_KERNEL; > +#else > + return PAGE_KERNEL_EXEC; > +#endif /* CONFIG_64BIT */ > +} > +#endif /* CONFIG_STRICT_KERNEL_RWX */ > + > /* > * setup_vm() is called from head.S with MMU-off. > * > @@ -454,7 +511,8 @@ uintptr_t xiprom, xiprom_sz; > #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; > > @@ -473,7 +531,7 @@ 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; > > @@ -481,7 +539,7 @@ 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 > > @@ -558,7 +616,7 @@ 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 */ > @@ -634,22 +692,6 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) > #endif > } > > -#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX) > -void 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; > @@ -682,21 +724,15 @@ 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 */ > @@ -727,35 +763,6 @@ 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 > -- > 2.30.2 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
I wanted to try testing this on the BeagleV Starlight but I could not apply it cleanly against 5.13-rc3:
$ git am /tmp/patch.am Applying: riscv: Map the kernel with correct permissions the first time error: patch failed: arch/riscv/include/asm/page.h:95 error: arch/riscv/include/asm/page.h: patch does not apply Patch failed at 0001 riscv: Map the kernel with correct permissions the first time hint: Use 'git am --show-current-patch=diff' to see the failed patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort".
Is there another branch I should be looking at?
thanks, drew
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