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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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1623963097
Impact: keep kernel text read only Because dynamic ftrace converts the calls to mcount into and out of nops at run time, we needed to always keep the kernel text writable. But this defeats the point of CONFIG_DEBUG_RODATA. This patch converts the kernel code to writable before ftrace modifies the text, and converts it back to read only afterward. The kernel text is converted to read/write, stop_machine is called to modify the code, then the kernel text is converted back to read only. The original version used SYSTEM_STATE to determine when it was OK or not to change the code to rw or ro. Andrew Morton pointed out that using SYSTEM_STATE is a bad idea since there is no guarantee to what its state will actually be. Instead, I moved the check into the set_kernel_text_* functions themselves, and use a local variable to determine when it is OK to change the kernel text RW permissions. [ Update: Ingo Molnar suggested moving the prototypes to cacheflush.h ] Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
124 lines
4.6 KiB
C
124 lines
4.6 KiB
C
#ifndef _ASM_X86_CACHEFLUSH_H
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#define _ASM_X86_CACHEFLUSH_H
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/* Keep includes the same across arches. */
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#include <linux/mm.h>
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/* Caches aren't brain-dead on the intel. */
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#define flush_cache_all() do { } while (0)
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#define flush_cache_mm(mm) do { } while (0)
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#define flush_cache_dup_mm(mm) do { } while (0)
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#define flush_cache_range(vma, start, end) do { } while (0)
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#define flush_cache_page(vma, vmaddr, pfn) do { } while (0)
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#define flush_dcache_page(page) do { } while (0)
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#define flush_dcache_mmap_lock(mapping) do { } while (0)
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#define flush_dcache_mmap_unlock(mapping) do { } while (0)
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#define flush_icache_range(start, end) do { } while (0)
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#define flush_icache_page(vma, pg) do { } while (0)
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#define flush_icache_user_range(vma, pg, adr, len) do { } while (0)
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#define flush_cache_vmap(start, end) do { } while (0)
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#define flush_cache_vunmap(start, end) do { } while (0)
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#define copy_to_user_page(vma, page, vaddr, dst, src, len) \
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memcpy((dst), (src), (len))
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#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
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memcpy((dst), (src), (len))
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#define PG_non_WB PG_arch_1
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PAGEFLAG(NonWB, non_WB)
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/*
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* The set_memory_* API can be used to change various attributes of a virtual
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* address range. The attributes include:
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* Cachability : UnCached, WriteCombining, WriteBack
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* Executability : eXeutable, NoteXecutable
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* Read/Write : ReadOnly, ReadWrite
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* Presence : NotPresent
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*
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* Within a catagory, the attributes are mutually exclusive.
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*
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* The implementation of this API will take care of various aspects that
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* are associated with changing such attributes, such as:
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* - Flushing TLBs
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* - Flushing CPU caches
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* - Making sure aliases of the memory behind the mapping don't violate
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* coherency rules as defined by the CPU in the system.
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*
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* What this API does not do:
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* - Provide exclusion between various callers - including callers that
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* operation on other mappings of the same physical page
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* - Restore default attributes when a page is freed
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* - Guarantee that mappings other than the requested one are
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* in any state, other than that these do not violate rules for
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* the CPU you have. Do not depend on any effects on other mappings,
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* CPUs other than the one you have may have more relaxed rules.
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* The caller is required to take care of these.
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*/
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int _set_memory_uc(unsigned long addr, int numpages);
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int _set_memory_wc(unsigned long addr, int numpages);
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int _set_memory_wb(unsigned long addr, int numpages);
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int set_memory_uc(unsigned long addr, int numpages);
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int set_memory_wc(unsigned long addr, int numpages);
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int set_memory_wb(unsigned long addr, int numpages);
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int set_memory_x(unsigned long addr, int numpages);
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int set_memory_nx(unsigned long addr, int numpages);
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int set_memory_ro(unsigned long addr, int numpages);
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int set_memory_rw(unsigned long addr, int numpages);
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int set_memory_np(unsigned long addr, int numpages);
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int set_memory_4k(unsigned long addr, int numpages);
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int set_memory_array_uc(unsigned long *addr, int addrinarray);
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int set_memory_array_wb(unsigned long *addr, int addrinarray);
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/*
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* For legacy compatibility with the old APIs, a few functions
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* are provided that work on a "struct page".
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* These functions operate ONLY on the 1:1 kernel mapping of the
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* memory that the struct page represents, and internally just
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* call the set_memory_* function. See the description of the
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* set_memory_* function for more details on conventions.
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*
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* These APIs should be considered *deprecated* and are likely going to
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* be removed in the future.
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* The reason for this is the implicit operation on the 1:1 mapping only,
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* making this not a generally useful API.
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*
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* Specifically, many users of the old APIs had a virtual address,
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* called virt_to_page() or vmalloc_to_page() on that address to
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* get a struct page* that the old API required.
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* To convert these cases, use set_memory_*() on the original
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* virtual address, do not use these functions.
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*/
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int set_pages_uc(struct page *page, int numpages);
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int set_pages_wb(struct page *page, int numpages);
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int set_pages_x(struct page *page, int numpages);
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int set_pages_nx(struct page *page, int numpages);
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int set_pages_ro(struct page *page, int numpages);
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int set_pages_rw(struct page *page, int numpages);
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void clflush_cache_range(void *addr, unsigned int size);
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#ifdef CONFIG_DEBUG_RODATA
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void mark_rodata_ro(void);
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extern const int rodata_test_data;
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void set_kernel_text_rw(void);
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void set_kernel_text_ro(void);
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#else
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static inline void set_kernel_text_rw(void) { }
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static inline void set_kernel_text_ro(void) { }
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#endif
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#ifdef CONFIG_DEBUG_RODATA_TEST
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int rodata_test(void);
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#else
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static inline int rodata_test(void)
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{
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return 0;
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}
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#endif
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#endif /* _ASM_X86_CACHEFLUSH_H */
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