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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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62b94a08da
Discourage drivers/modules to be creative with preemption. Sadly all is implemented in macros and inline so if they want to do evil they still can, but at least try and discourage some. Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith <bitbucket@online.de> Cc: hpa@zytor.com Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-fn7h6vu8wtgxk0ih402qcijx@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
111 lines
3.4 KiB
C
111 lines
3.4 KiB
C
#ifndef __LINUX_UACCESS_H__
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#define __LINUX_UACCESS_H__
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#include <linux/preempt.h>
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#include <asm/uaccess.h>
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/*
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* These routines enable/disable the pagefault handler in that
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* it will not take any locks and go straight to the fixup table.
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*
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* They have great resemblance to the preempt_disable/enable calls
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* and in fact they are identical; this is because currently there is
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* no other way to make the pagefault handlers do this. So we do
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* disable preemption but we don't necessarily care about that.
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*/
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static inline void pagefault_disable(void)
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{
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preempt_count_inc();
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/*
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* make sure to have issued the store before a pagefault
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* can hit.
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*/
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barrier();
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}
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static inline void pagefault_enable(void)
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{
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#ifndef CONFIG_PREEMPT
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/*
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* make sure to issue those last loads/stores before enabling
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* the pagefault handler again.
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*/
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barrier();
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preempt_count_dec();
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#else
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preempt_enable();
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#endif
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}
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#ifndef ARCH_HAS_NOCACHE_UACCESS
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static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
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const void __user *from, unsigned long n)
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{
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return __copy_from_user_inatomic(to, from, n);
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}
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static inline unsigned long __copy_from_user_nocache(void *to,
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const void __user *from, unsigned long n)
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{
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return __copy_from_user(to, from, n);
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}
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#endif /* ARCH_HAS_NOCACHE_UACCESS */
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/**
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* probe_kernel_address(): safely attempt to read from a location
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* @addr: address to read from - its type is type typeof(retval)*
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* @retval: read into this variable
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*
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* Safely read from address @addr into variable @revtal. If a kernel fault
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* happens, handle that and return -EFAULT.
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* We ensure that the __get_user() is executed in atomic context so that
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* do_page_fault() doesn't attempt to take mmap_sem. This makes
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* probe_kernel_address() suitable for use within regions where the caller
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* already holds mmap_sem, or other locks which nest inside mmap_sem.
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* This must be a macro because __get_user() needs to know the types of the
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* args.
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*
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* We don't include enough header files to be able to do the set_fs(). We
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* require that the probe_kernel_address() caller will do that.
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*/
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#define probe_kernel_address(addr, retval) \
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({ \
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long ret; \
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mm_segment_t old_fs = get_fs(); \
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\
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set_fs(KERNEL_DS); \
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pagefault_disable(); \
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ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \
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pagefault_enable(); \
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set_fs(old_fs); \
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ret; \
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})
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/*
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* probe_kernel_read(): safely attempt to read from a location
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* @dst: pointer to the buffer that shall take the data
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* @src: address to read from
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* @size: size of the data chunk
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*
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* Safely read from address @src to the buffer at @dst. If a kernel fault
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* happens, handle that and return -EFAULT.
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*/
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extern long probe_kernel_read(void *dst, const void *src, size_t size);
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extern long __probe_kernel_read(void *dst, const void *src, size_t size);
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/*
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* probe_kernel_write(): safely attempt to write to a location
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* @dst: address to write to
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* @src: pointer to the data that shall be written
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* @size: size of the data chunk
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*
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* Safely write to address @dst from the buffer at @src. If a kernel fault
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* happens, handle that and return -EFAULT.
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*/
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extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
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extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
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#endif /* __LINUX_UACCESS_H__ */
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