diff options
Diffstat (limited to 'arch/cris/arch-v32/lib/usercopy.c')
| -rw-r--r-- | arch/cris/arch-v32/lib/usercopy.c | 470 |
1 files changed, 470 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/lib/usercopy.c b/arch/cris/arch-v32/lib/usercopy.c new file mode 100644 index 000000000000..f0b08460c1be --- /dev/null +++ b/arch/cris/arch-v32/lib/usercopy.c @@ -0,0 +1,470 @@ +/* + * User address space access functions. + * The non-inlined parts of asm-cris/uaccess.h are here. + * + * Copyright (C) 2000, 2003 Axis Communications AB. + * + * Written by Hans-Peter Nilsson. + * Pieces used from memcpy, originally by Kenny Ranerup long time ago. + */ + +#include <asm/uaccess.h> + +/* Asm:s have been tweaked (within the domain of correctness) to give + satisfactory results for "gcc version 3.2.1 Axis release R53/1.53-v32". + + Check regularly... + + Note that for CRISv32, the PC saved at a bus-fault is the address + *at* the faulting instruction, with a special case for instructions + in delay slots: then it's the address of the branch. Note also that + in contrast to v10, a postincrement in the instruction is *not* + performed at a bus-fault; the register is seen having the original + value in fault handlers. */ + + +/* Copy to userspace. This is based on the memcpy used for + kernel-to-kernel copying; see "string.c". */ + +unsigned long +__copy_user (void __user *pdst, const void *psrc, unsigned long pn) +{ + /* We want the parameters put in special registers. + Make sure the compiler is able to make something useful of this. + As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop). + + FIXME: Comment for old gcc version. Check. + If gcc was allright, it really would need no temporaries, and no + stack space to save stuff on. */ + + register char *dst __asm__ ("r13") = pdst; + register const char *src __asm__ ("r11") = psrc; + register int n __asm__ ("r12") = pn; + register int retn __asm__ ("r10") = 0; + + + /* When src is aligned but not dst, this makes a few extra needless + cycles. I believe it would take as many to check that the + re-alignment was unnecessary. */ + if (((unsigned long) dst & 3) != 0 + /* Don't align if we wouldn't copy more than a few bytes; so we + don't have to check further for overflows. */ + && n >= 3) + { + if ((unsigned long) dst & 1) + { + __asm_copy_to_user_1 (dst, src, retn); + n--; + } + + if ((unsigned long) dst & 2) + { + __asm_copy_to_user_2 (dst, src, retn); + n -= 2; + } + } + + /* Movem is dirt cheap. The overheap is low enough to always use the + minimum possible block size as the threshold. */ + if (n >= 44) + { + /* For large copies we use 'movem'. */ + + /* It is not optimal to tell the compiler about clobbering any + registers; that will move the saving/restoring of those registers + to the function prologue/epilogue, and make non-movem sizes + suboptimal. */ + __asm__ volatile ("\ + ;; Check that the register asm declaration got right. \n\ + ;; The GCC manual explicitly says TRT will happen. \n\ + .ifnc %0%1%2%3,$r13$r11$r12$r10 \n\ + .err \n\ + .endif \n\ + \n\ + ;; Save the registers we'll use in the movem process \n\ + ;; on the stack. \n\ + subq 11*4,$sp \n\ + movem $r10,[$sp] \n\ + \n\ + ;; Now we've got this: \n\ + ;; r11 - src \n\ + ;; r13 - dst \n\ + ;; r12 - n \n\ + \n\ + ;; Update n for the first loop \n\ + subq 44,$r12 \n\ +0: \n\ + movem [$r11+],$r10 \n\ + subq 44,$r12 \n\ +1: bge 0b \n\ + movem $r10,[$r13+] \n\ +3: \n\ + addq 44,$r12 ;; compensate for last loop underflowing n \n\ + \n\ + ;; Restore registers from stack \n\ + movem [$sp+],$r10 \n\ +2: \n\ + .section .fixup,\"ax\" \n\ +4: \n\ +; When failing on any of the 1..44 bytes in a chunk, we adjust back the \n\ +; source pointer and just drop through to the by-16 and by-4 loops to \n\ +; get the correct number of failing bytes. This necessarily means a \n\ +; few extra exceptions, but invalid user pointers shouldn't happen in \n\ +; time-critical code anyway. \n\ + jump 3b \n\ + subq 44,$r11 \n\ + \n\ + .previous \n\ + .section __ex_table,\"a\" \n\ + .dword 1b,4b \n\ + .previous" + + /* Outputs */ : "=r" (dst), "=r" (src), "=r" (n), "=r" (retn) + /* Inputs */ : "0" (dst), "1" (src), "2" (n), "3" (retn)); + + } + + while (n >= 16) + { + __asm_copy_to_user_16 (dst, src, retn); + n -= 16; + } + + /* Having a separate by-four loops cuts down on cache footprint. + FIXME: Test with and without; increasing switch to be 0..15. */ + while (n >= 4) + { + __asm_copy_to_user_4 (dst, src, retn); + n -= 4; + } + + switch (n) + { + case 0: + break; + case 1: + __asm_copy_to_user_1 (dst, src, retn); + break; + case 2: + __asm_copy_to_user_2 (dst, src, retn); + break; + case 3: + __asm_copy_to_user_3 (dst, src, retn); + break; + } + + return retn; +} + +/* Copy from user to kernel, zeroing the bytes that were inaccessible in + userland. The return-value is the number of bytes that were + inaccessible. */ + +unsigned long +__copy_user_zeroing (void __user *pdst, const void *psrc, unsigned long pn) +{ + /* We want the parameters put in special registers. + Make sure the compiler is able to make something useful of this. + As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop). + + FIXME: Comment for old gcc version. Check. + If gcc was allright, it really would need no temporaries, and no + stack space to save stuff on. */ + + register char *dst __asm__ ("r13") = pdst; + register const char *src __asm__ ("r11") = psrc; + register int n __asm__ ("r12") = pn; + register int retn __asm__ ("r10") = 0; + + /* The best reason to align src is that we then know that a read-fault + was for aligned bytes; there's no 1..3 remaining good bytes to + pickle. */ + if (((unsigned long) src & 3) != 0) + { + if (((unsigned long) src & 1) && n != 0) + { + __asm_copy_from_user_1 (dst, src, retn); + n--; + } + + if (((unsigned long) src & 2) && n >= 2) + { + __asm_copy_from_user_2 (dst, src, retn); + n -= 2; + } + + /* We only need one check after the unalignment-adjustments, because + if both adjustments were done, either both or neither reference + had an exception. */ + if (retn != 0) + goto copy_exception_bytes; + } + + /* Movem is dirt cheap. The overheap is low enough to always use the + minimum possible block size as the threshold. */ + if (n >= 44) + { + /* It is not optimal to tell the compiler about clobbering any + registers; that will move the saving/restoring of those registers + to the function prologue/epilogue, and make non-movem sizes + suboptimal. */ + __asm__ volatile ("\ + .ifnc %0%1%2%3,$r13$r11$r12$r10 \n\ + .err \n\ + .endif \n\ + \n\ + ;; Save the registers we'll use in the movem process \n\ + ;; on the stack. \n\ + subq 11*4,$sp \n\ + movem $r10,[$sp] \n\ + \n\ + ;; Now we've got this: \n\ + ;; r11 - src \n\ + ;; r13 - dst \n\ + ;; r12 - n \n\ + \n\ + ;; Update n for the first loop \n\ + subq 44,$r12 \n\ +0: \n\ + movem [$r11+],$r10 \n\ + \n\ + subq 44,$r12 \n\ + bge 0b \n\ + movem $r10,[$r13+] \n\ + \n\ +4: \n\ + addq 44,$r12 ;; compensate for last loop underflowing n \n\ + \n\ + ;; Restore registers from stack \n\ + movem [$sp+],$r10 \n\ + .section .fixup,\"ax\" \n\ + \n\ +;; Do not jump back into the loop if we fail. For some uses, we get a \n\ +;; page fault somewhere on the line. Without checking for page limits, \n\ +;; we don't know where, but we need to copy accurately and keep an \n\ +;; accurate count; not just clear the whole line. To do that, we fall \n\ +;; down in the code below, proceeding with smaller amounts. It should \n\ +;; be kept in mind that we have to cater to code like what at one time \n\ +;; was in fs/super.c: \n\ +;; i = size - copy_from_user((void *)page, data, size); \n\ +;; which would cause repeated faults while clearing the remainder of \n\ +;; the SIZE bytes at PAGE after the first fault. \n\ +;; A caveat here is that we must not fall through from a failing page \n\ +;; to a valid page. \n\ + \n\ +3: \n\ + jump 4b ;; Fall through, pretending the fault didn't happen. \n\ + nop \n\ + \n\ + .previous \n\ + .section __ex_table,\"a\" \n\ + .dword 0b,3b \n\ + .previous" + + /* Outputs */ : "=r" (dst), "=r" (src), "=r" (n), "=r" (retn) + /* Inputs */ : "0" (dst), "1" (src), "2" (n), "3" (retn)); + } + + /* Either we directly start copying here, using dword copying in a loop, + or we copy as much as possible with 'movem' and then the last block + (<44 bytes) is copied here. This will work since 'movem' will have + updated src, dst and n. (Except with failing src.) + + Since we want to keep src accurate, we can't use + __asm_copy_from_user_N with N != (1, 2, 4); it updates dst and + retn, but not src (by design; it's value is ignored elsewhere). */ + + while (n >= 4) + { + __asm_copy_from_user_4 (dst, src, retn); + n -= 4; + + if (retn) + goto copy_exception_bytes; + } + + /* If we get here, there were no memory read faults. */ + switch (n) + { + /* These copies are at least "naturally aligned" (so we don't have + to check each byte), due to the src alignment code before the + movem loop. The *_3 case *will* get the correct count for retn. */ + case 0: + /* This case deliberately left in (if you have doubts check the + generated assembly code). */ + break; + case 1: + __asm_copy_from_user_1 (dst, src, retn); + break; + case 2: + __asm_copy_from_user_2 (dst, src, retn); + break; + case 3: + __asm_copy_from_user_3 (dst, src, retn); + break; + } + + /* If we get here, retn correctly reflects the number of failing + bytes. */ + return retn; + +copy_exception_bytes: + /* We already have "retn" bytes cleared, and need to clear the + remaining "n" bytes. A non-optimized simple byte-for-byte in-line + memset is preferred here, since this isn't speed-critical code and + we'd rather have this a leaf-function than calling memset. */ + { + char *endp; + for (endp = dst + n; dst < endp; dst++) + *dst = 0; + } + + return retn + n; +} + +/* Zero userspace. */ + +unsigned long +__do_clear_user (void __user *pto, unsigned long pn) +{ + /* We want the parameters put in special registers. + Make sure the compiler is able to make something useful of this. + As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop). + + FIXME: Comment for old gcc version. Check. + If gcc was allright, it really would need no temporaries, and no + stack space to save stuff on. */ + + register char *dst __asm__ ("r13") = pto; + register int n __asm__ ("r12") = pn; + register int retn __asm__ ("r10") = 0; + + + if (((unsigned long) dst & 3) != 0 + /* Don't align if we wouldn't copy more than a few bytes. */ + && n >= 3) + { + if ((unsigned long) dst & 1) + { + __asm_clear_1 (dst, retn); + n--; + } + + if ((unsigned long) dst & 2) + { + __asm_clear_2 (dst, retn); + n -= 2; + } + } + + /* Decide which copying method to use. + FIXME: This number is from the "ordinary" kernel memset. */ + if (n >= 48) + { + /* For large clears we use 'movem' */ + + /* It is not optimal to tell the compiler about clobbering any + call-saved registers; that will move the saving/restoring of + those registers to the function prologue/epilogue, and make + non-movem sizes suboptimal. + + This method is not foolproof; it assumes that the "asm reg" + declarations at the beginning of the function really are used + here (beware: they may be moved to temporary registers). + This way, we do not have to save/move the registers around into + temporaries; we can safely use them straight away. + + If you want to check that the allocation was right; then + check the equalities in the first comment. It should say + something like "r13=r13, r11=r11, r12=r12". */ + __asm__ volatile ("\ + .ifnc %0%1%2,$r13$r12$r10 \n\ + .err \n\ + .endif \n\ + \n\ + ;; Save the registers we'll clobber in the movem process \n\ + ;; on the stack. Don't mention them to gcc, it will only be \n\ + ;; upset. \n\ + subq 11*4,$sp \n\ + movem $r10,[$sp] \n\ + \n\ + clear.d $r0 \n\ + clear.d $r1 \n\ + clear.d $r2 \n\ + clear.d $r3 \n\ + clear.d $r4 \n\ + clear.d $r5 \n\ + clear.d $r6 \n\ + clear.d $r7 \n\ + clear.d $r8 \n\ + clear.d $r9 \n\ + clear.d $r10 \n\ + clear.d $r11 \n\ + \n\ + ;; Now we've got this: \n\ + ;; r13 - dst \n\ + ;; r12 - n \n\ + \n\ + ;; Update n for the first loop \n\ + subq 12*4,$r12 \n\ +0: \n\ + subq 12*4,$r12 \n\ +1: \n\ + bge 0b \n\ + movem $r11,[$r13+] \n\ + \n\ + addq 12*4,$r12 ;; compensate for last loop underflowing n \n\ + \n\ + ;; Restore registers from stack \n\ + movem [$sp+],$r10 \n\ +2: \n\ + .section .fixup,\"ax\" \n\ +3: \n\ + movem [$sp],$r10 \n\ + addq 12*4,$r10 \n\ + addq 12*4,$r13 \n\ + movem $r10,[$sp] \n\ + jump 0b \n\ + clear.d $r10 \n\ + \n\ + .previous \n\ + .section __ex_table,\"a\" \n\ + .dword 1b,3b \n\ + .previous" + + /* Outputs */ : "=r" (dst), "=r" (n), "=r" (retn) + /* Inputs */ : "0" (dst), "1" (n), "2" (retn) + /* Clobber */ : "r11"); + } + + while (n >= 16) + { + __asm_clear_16 (dst, retn); + n -= 16; + } + + /* Having a separate by-four loops cuts down on cache footprint. + FIXME: Test with and without; increasing switch to be 0..15. */ + while (n >= 4) + { + __asm_clear_4 (dst, retn); + n -= 4; + } + + switch (n) + { + case 0: + break; + case 1: + __asm_clear_1 (dst, retn); + break; + case 2: + __asm_clear_2 (dst, retn); + break; + case 3: + __asm_clear_3 (dst, retn); + break; + } + + return retn; +} |