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Diffstat (limited to 'arch/cris/arch-v32/lib/usercopy.c')
-rw-r--r--arch/cris/arch-v32/lib/usercopy.c469
1 files changed, 469 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/lib/usercopy.c b/arch/cris/arch-v32/lib/usercopy.c
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index 000000000..f0f335d8a
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+/*
+ * 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 alright, 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;
+}
+EXPORT_SYMBOL(__copy_user);
+
+/* 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 *pdst, const void __user *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 alright, 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;
+}
+EXPORT_SYMBOL(__copy_user_zeroing);
+
+/* 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 alright, 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;
+}
+EXPORT_SYMBOL(__do_clear_user);
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