ARM: implement arch_cpu_user_memcpy/memset/strlcpy functions
Remove the dummies from the C code and implement them in assembly, due to the label referencing issues with the fault handler. This code is ripe for optimisation, my ARM assembly is pretty basic ;) Does work though, and gets us one step closer to a full arch.
This commit is contained in:
Ithamar R. Adema
parent
75b285a969
commit
4b2a1d798b
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@ -94,6 +94,116 @@ FUNCTION(arm_get_far):
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bx lr
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FUNCTION_END(arm_get_far)
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/* status_t arch_cpu_user_memcpy(void *to, const void *from, size_t size, addr_t *faultHandler) */
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FUNCTION(arch_cpu_user_memcpy):
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stmfd sp!, { r4-r6 }
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ldr r6, [r3]
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ldr r4, =.L_user_memcpy_error
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str r4, [r3] /* set fault handler */
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mov r4, r2, lsr #2 /* size / 4 */
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1:
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ldr r5, [r1]
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str r5, [r0]
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add r1, #4
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add r0, #4
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sub r4, #1
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bne 1b
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2:
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and r4, r2, #3 /* size % 4 */
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ldrb r5, [r1]
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strb r5, [r0]
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add r1, #1
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add r0, #1
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sub r4, #1
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bne 2b
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str r6, [r3] /* restore fault handler */
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mov r0, #0
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ldmfd sp!, { r4-r6 }
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bx lr
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.L_user_memcpy_error:
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str r6, [r3] /* restore fault handler */
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mov r0, #-1
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ldmfd sp!, { r4-r6 }
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bx lr
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FUNCTION_END(arch_cpu_user_memcpy)
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/* status_t arch_cpu_user_memset(void *to, char c, size_t count, addr_t *faultHandler) */
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FUNCTION(arch_cpu_user_memset):
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stmfd sp!, { r4-r5 }
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ldr r5, [r3]
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ldr r4, =.L_user_memset_error
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str r4, [r3]
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and r1, r1, #0xff
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add r1, r1, lsl #8
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add r1, r1, lsl #16
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add r1, r1, lsl #24
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mov r4, r2, lsr #2 /* count / 4 */
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1:
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str r1, [r0]
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add r0, r0, #4
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sub r4, r4, #1
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bne 1b
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and r4, r2, #3 /* count % 4 */
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2:
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strb r1, [r0]
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add r0, r0, #1
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sub r4, r4, #1
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bne 2b
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mov r0, #0
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str r5, [r3]
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ldmfd sp!, { r4-r5 }
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bx lr
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.L_user_memset_error:
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mov r0, #-1
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str r5, [r3]
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ldmfd sp!, { r4-r5 }
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bx lr
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FUNCTION_END(arch_cpu_user_memset)
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/* ssize_t arch_cpu_user_strlcpy(void *to, const void *from, size_t size, addr_t *faultHandler) */
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FUNCTION(arch_cpu_user_strlcpy):
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stmfd sp!, { r4-r6 }
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ldr r5, [r3]
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ldr r4, =.L_user_strlcpy_error
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str r4, [r3]
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mov r6, #0
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1:
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ldrb r4, [r1, r6]
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strb r4, [r0, r6]
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add r6, r6, #1
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and r4, #0xff /* done yet? */
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beq 2f
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cmp r6, r2 /* reached max length? */
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blt 1b
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2:
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mov r4, #0
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strb r4, [r0, r6]
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mov r0, r4 /* return B_OK */
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str r5, [r3] /* restore fault handler */
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ldmfd sp!, { r4-r6 }
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bx lr
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.L_user_strlcpy_error:
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mov r0, #-1
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str r5, [r3]
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ldmfd sp!, { r4-r6 }
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bx lr
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FUNCTION_END(arch_cpu_user_strlcpy)
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/*! \fn void arch_debug_call_with_fault_handler(cpu_ent* cpu,
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jmp_buf jumpBuffer, void (*function)(void*), void* parameter)
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@ -159,119 +159,3 @@ arch_cpu_user_TLB_invalidate(void)
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*/
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#warning WRITEME
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}
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// TODO: all functions that use fault handlers need to be implemented
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// in assembly due to problems passing in label addresses in gcc4.
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status_t
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arch_cpu_user_memcpy(void *to, const void *from, size_t size,
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addr_t *faultHandler)
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{
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#warning WRITEME
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/*
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char *tmp = (char *)to;
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char *s = (char *)from;
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addr_t oldFaultHandler = *faultHandler;
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if (m68k_set_fault_handler(faultHandler, (addr_t)&&error))
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goto error;
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while (size--)
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*tmp++ = *s++;
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*faultHandler = oldFaultHandler;
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return 0;
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error:
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*faultHandler = oldFaultHandler;*/
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return B_BAD_ADDRESS;
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}
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/** \brief Copies at most (\a size - 1) characters from the string in \a from to
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* the string in \a to, NULL-terminating the result.
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*
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* \param to Pointer to the destination C-string.
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* \param from Pointer to the source C-string.
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* \param size Size in bytes of the string buffer pointed to by \a to.
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*
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* \return strlen(\a from).
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*/
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ssize_t
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arch_cpu_user_strlcpy(char *to, const char *from,
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size_t size, addr_t *faultHandler)
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{
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#warning WRITEME
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/*
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int from_length = 0;
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addr_t oldFaultHandler = *faultHandler;
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if (m68k_set_fault_handler(faultHandler, (addr_t)&&error))
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goto error;
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if (size > 0) {
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to[--size] = '\0';
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// copy
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for ( ; size; size--, from_length++, to++, from++) {
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if ((*to = *from) == '\0')
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break;
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}
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}
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// count any leftover from chars
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while (*from++ != '\0')
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from_length++;
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*faultHandler = oldFaultHandler;
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return from_length;
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error:
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*faultHandler = oldFaultHandler;*/
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return B_BAD_ADDRESS;
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}
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status_t
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arch_cpu_user_memset(void *s, char c, size_t count, addr_t *faultHandler)
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{
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#warning WRITEME
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/*
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char *xs = (char *)s;
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addr_t oldFaultHandler = *faultHandler;
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if (m68k_set_fault_handler(faultHandler, (addr_t)&&error))
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goto error;
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while (count--)
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*xs++ = c;
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*faultHandler = oldFaultHandler;
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return 0;
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error:
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*faultHandler = oldFaultHandler;*/
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return B_BAD_ADDRESS;
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}
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// The purpose of this function is to trick the compiler. When setting the
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// page_handler to a label that is obviously (to the compiler) never used,
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// it may reorganize the control flow, so that the labeled part is optimized
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// away.
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// By invoking the function like this
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//
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// if (m68k_set_fault_handler(faultHandler, (addr_t)&&error))
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// goto error;
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//
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// the compiler has to keep the labeled code, since it can't guess the return
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// value of this (non-inlinable) function. At least in my tests it worked that
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// way, and I hope it will continue to work like this in the future.
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//
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/*bool
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m68k_set_fault_handler(addr_t *handlerLocation, addr_t handler)
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{
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*handlerLocation = handler;
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return false;
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}*/
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