forked from mirrors/linux
736706bee3
Every in-kernel use of this function defined it to KERNEL_DS (either as an actual define, or as an inline function). It's an entirely historical artifact, and long long long ago used to actually read the segment selector valueof '%ds' on x86. Which in the kernel is always KERNEL_DS. Inspired by a patch from Jann Horn that just did this for a very small subset of users (the ones in fs/), along with Al who suggested a script. I then just took it to the logical extreme and removed all the remaining gunk. Roughly scripted with git grep -l '(get_ds())' -- :^tools/ | xargs sed -i 's/(get_ds())/(KERNEL_DS)/' git grep -lw 'get_ds' -- :^tools/ | xargs sed -i '/^#define get_ds()/d' plus manual fixups to remove a few unusual usage patterns, the couple of inline function cases and to fix up a comment that had become stale. The 'get_ds()' function remains in an x86 kvm selftest, since in user space it actually does something relevant. Inspired-by: Jann Horn <jannh@google.com> Inspired-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
226 lines
6.5 KiB
C
226 lines
6.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __PARISC_UACCESS_H
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#define __PARISC_UACCESS_H
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/*
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* User space memory access functions
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*/
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#include <asm/page.h>
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#include <asm/cache.h>
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#include <linux/bug.h>
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#include <linux/string.h>
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#define KERNEL_DS ((mm_segment_t){0})
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#define USER_DS ((mm_segment_t){1})
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#define segment_eq(a, b) ((a).seg == (b).seg)
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#define get_fs() (current_thread_info()->addr_limit)
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#define set_fs(x) (current_thread_info()->addr_limit = (x))
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/*
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* Note that since kernel addresses are in a separate address space on
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* parisc, we don't need to do anything for access_ok().
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* We just let the page fault handler do the right thing. This also means
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* that put_user is the same as __put_user, etc.
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*/
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#define access_ok(uaddr, size) \
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( (uaddr) == (uaddr) )
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#define put_user __put_user
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#define get_user __get_user
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#if !defined(CONFIG_64BIT)
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#define LDD_USER(val, ptr) __get_user_asm64(val, ptr)
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#define STD_USER(x, ptr) __put_user_asm64(x, ptr)
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#else
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#define LDD_USER(val, ptr) __get_user_asm(val, "ldd", ptr)
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#define STD_USER(x, ptr) __put_user_asm("std", x, ptr)
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#endif
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/*
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* The exception table contains two values: the first is the relative offset to
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* the address of the instruction that is allowed to fault, and the second is
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* the relative offset to the address of the fixup routine. Since relative
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* addresses are used, 32bit values are sufficient even on 64bit kernel.
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*/
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#define ARCH_HAS_RELATIVE_EXTABLE
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struct exception_table_entry {
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int insn; /* relative address of insn that is allowed to fault. */
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int fixup; /* relative address of fixup routine */
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};
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#define ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr )\
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".section __ex_table,\"aw\"\n" \
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".word (" #fault_addr " - .), (" #except_addr " - .)\n\t" \
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".previous\n"
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/*
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* ASM_EXCEPTIONTABLE_ENTRY_EFAULT() creates a special exception table entry
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* (with lowest bit set) for which the fault handler in fixup_exception() will
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* load -EFAULT into %r8 for a read or write fault, and zeroes the target
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* register in case of a read fault in get_user().
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*/
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#define ASM_EXCEPTIONTABLE_ENTRY_EFAULT( fault_addr, except_addr )\
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ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr + 1)
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/*
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* load_sr2() preloads the space register %%sr2 - based on the value of
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* get_fs() - with either a value of 0 to access kernel space (KERNEL_DS which
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* is 0), or with the current value of %%sr3 to access user space (USER_DS)
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* memory. The following __get_user_asm() and __put_user_asm() functions have
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* %%sr2 hard-coded to access the requested memory.
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*/
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#define load_sr2() \
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__asm__(" or,= %0,%%r0,%%r0\n\t" \
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" mfsp %%sr3,%0\n\t" \
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" mtsp %0,%%sr2\n\t" \
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: : "r"(get_fs()) : )
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#define __get_user_internal(val, ptr) \
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({ \
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register long __gu_err __asm__ ("r8") = 0; \
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\
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switch (sizeof(*(ptr))) { \
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case 1: __get_user_asm(val, "ldb", ptr); break; \
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case 2: __get_user_asm(val, "ldh", ptr); break; \
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case 4: __get_user_asm(val, "ldw", ptr); break; \
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case 8: LDD_USER(val, ptr); break; \
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default: BUILD_BUG(); \
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} \
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\
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__gu_err; \
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})
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#define __get_user(val, ptr) \
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({ \
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load_sr2(); \
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__get_user_internal(val, ptr); \
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})
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#define __get_user_asm(val, ldx, ptr) \
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{ \
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register long __gu_val; \
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\
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__asm__("1: " ldx " 0(%%sr2,%2),%0\n" \
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"9:\n" \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
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: "=r"(__gu_val), "=r"(__gu_err) \
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: "r"(ptr), "1"(__gu_err)); \
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\
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(val) = (__force __typeof__(*(ptr))) __gu_val; \
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}
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#if !defined(CONFIG_64BIT)
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#define __get_user_asm64(val, ptr) \
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{ \
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union { \
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unsigned long long l; \
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__typeof__(*(ptr)) t; \
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} __gu_tmp; \
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\
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__asm__(" copy %%r0,%R0\n" \
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"1: ldw 0(%%sr2,%2),%0\n" \
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"2: ldw 4(%%sr2,%2),%R0\n" \
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"9:\n" \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
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: "=&r"(__gu_tmp.l), "=r"(__gu_err) \
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: "r"(ptr), "1"(__gu_err)); \
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\
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(val) = __gu_tmp.t; \
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}
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#endif /* !defined(CONFIG_64BIT) */
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#define __put_user_internal(x, ptr) \
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({ \
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register long __pu_err __asm__ ("r8") = 0; \
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__typeof__(*(ptr)) __x = (__typeof__(*(ptr)))(x); \
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\
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switch (sizeof(*(ptr))) { \
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case 1: __put_user_asm("stb", __x, ptr); break; \
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case 2: __put_user_asm("sth", __x, ptr); break; \
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case 4: __put_user_asm("stw", __x, ptr); break; \
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case 8: STD_USER(__x, ptr); break; \
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default: BUILD_BUG(); \
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} \
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\
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__pu_err; \
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})
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#define __put_user(x, ptr) \
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({ \
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load_sr2(); \
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__put_user_internal(x, ptr); \
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})
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/*
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* The "__put_user/kernel_asm()" macros tell gcc they read from memory
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* instead of writing. This is because they do not write to any memory
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* gcc knows about, so there are no aliasing issues. These macros must
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* also be aware that fixups are executed in the context of the fault,
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* and any registers used there must be listed as clobbers.
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* r8 is already listed as err.
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*/
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#define __put_user_asm(stx, x, ptr) \
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__asm__ __volatile__ ( \
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"1: " stx " %2,0(%%sr2,%1)\n" \
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"9:\n" \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
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: "=r"(__pu_err) \
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: "r"(ptr), "r"(x), "0"(__pu_err))
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#if !defined(CONFIG_64BIT)
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#define __put_user_asm64(__val, ptr) do { \
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__asm__ __volatile__ ( \
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"1: stw %2,0(%%sr2,%1)\n" \
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"2: stw %R2,4(%%sr2,%1)\n" \
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"9:\n" \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
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ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
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: "=r"(__pu_err) \
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: "r"(ptr), "r"(__val), "0"(__pu_err)); \
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} while (0)
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#endif /* !defined(CONFIG_64BIT) */
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/*
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* Complex access routines -- external declarations
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*/
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extern long strncpy_from_user(char *, const char __user *, long);
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extern unsigned lclear_user(void __user *, unsigned long);
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extern long lstrnlen_user(const char __user *, long);
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/*
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* Complex access routines -- macros
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*/
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#define user_addr_max() (~0UL)
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#define strnlen_user lstrnlen_user
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#define clear_user lclear_user
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#define __clear_user lclear_user
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unsigned long __must_check raw_copy_to_user(void __user *dst, const void *src,
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unsigned long len);
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unsigned long __must_check raw_copy_from_user(void *dst, const void __user *src,
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unsigned long len);
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unsigned long __must_check raw_copy_in_user(void __user *dst, const void __user *src,
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unsigned long len);
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#define INLINE_COPY_TO_USER
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#define INLINE_COPY_FROM_USER
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struct pt_regs;
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int fixup_exception(struct pt_regs *regs);
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#endif /* __PARISC_UACCESS_H */
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