145 lines
4.6 KiB
ArmAsm
145 lines
4.6 KiB
ArmAsm
#include <machine/asm.h>
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#include <ucontextoffsets.h>
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IMPORT(getuctx)
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IMPORT(setuctx)
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IMPORT(resumecontext)
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.globl _C_LABEL(__errno)
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/* int getcontext(ucontext_t *ucp)
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* Initialise the structure pointed to by ucp to the current user context
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* of the calling thread. */
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ENTRY(getcontext)
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ENTRY(_getcontext)
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/* In case a process does not use the FPU and is neither interested in
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* saving its signal mask, then we can skip the context switch to
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* PM and kernel altogether and only save general-purpose registers. */
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mov 4(%esp), %edx /* edx = ucp */
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/* Check null pointer */
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cmp $0, %edx /* edx == NULL? */
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jne 3f /* Not null, continue */
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PIC_PROLOGUE
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call PIC_PLT(_C_LABEL(__errno))
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PIC_EPILOGUE
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movl $EFAULT, (%eax)
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xor %eax, %eax
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dec %eax /* return -1 */
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ret
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3: /* Check flags */
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mov UC_FLAGS(%edx), %eax /* eax = ucp->uc_flags */
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and $[_UC_IGNFPU|_UC_IGNSIGM], %eax
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cmp $[_UC_IGNFPU|_UC_IGNSIGM], %eax
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jz 5f /* Ignore both, skip getuctx */
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PIC_PROLOGUE
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push %edx /* push a copy for us */
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push %edx /* push a copy as function argument */
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call PIC_PLT(_C_LABEL(getuctx)) /* getuctx(ucp) */
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pop %edx /* clean up stack */
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pop %edx /* clean up stack and restore edx */
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PIC_EPILOGUE
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5:
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/* Save the context */
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pop PC(%edx) /* Save real RTA in mcp struct */
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mov %esp, SP(%edx) /* Save stack pointer (now pointing to ucp) */
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/* Save GP registers (except EAX and EDX) */
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mov %ebp, BP(%edx) /* Save EBP */
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mov %esi, SI(%edx) /* Save ESI */
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mov %edi, DI(%edx) /* Save EDI */
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mov %ebx, BX(%edx) /* Save EBX */
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mov %ecx, CX(%edx) /* Save ECX */
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movl $MCF_MAGIC, MAGIC(%edx) /* Set magic value */
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xor %eax, %eax /* Return 0 */
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jmp *PC(%edx) /* Return return address */
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/* int setcontext(const ucontext_t *ucp)
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* Restore the user context pointed to by ucp. A successful call to
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* setcontext does not return; program execution resumes at the point
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* specified by the ucp argument. If ucp was created with getcontext(),
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* program execution continues as if the corresponding call of getcontext()
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* had just returned. If ucp was created with makecontext(), program
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* execution continues with the function passed to makecontext(). */
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ENTRY(setcontext)
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/* In case a process does not use the FPU and is neither interested in
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* restoring its signal mask, then we can skip the context switch to
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* PM and kernel altogether and restore state here. */
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mov 4(%esp), %edx /* edx = ucp */
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/* Check null pointer */
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cmp $0, %edx /* edx == NULL? */
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jnz 3f /* Not null, continue */
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movl $EFAULT, %edx
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0: push %edx /* preserve errno */
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PIC_PROLOGUE
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call PIC_PLT(_C_LABEL(__errno))
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PIC_EPILOGUE
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pop %edx
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movl %edx, (%eax)
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xor %eax, %eax
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dec %eax /* return -1 */
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ret
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3: /* Check flags */
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cmpl $MCF_MAGIC, MAGIC(%edx) /* is the magic value set (is context valid)?*/
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jz 4f /* is set, proceed */
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movl $EINVAL, %edx /* not set, return error code */
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jmp 0b
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4: mov UC_FLAGS(%edx), %eax /* eax = ucp->uc_flags */
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and $[_UC_IGNFPU|_UC_IGNSIGM], %eax
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cmp $[_UC_IGNFPU|_UC_IGNSIGM], %eax
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jz 5f /* Ignore both, so don't bother restoring FPU
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* state and signal mask */
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PIC_PROLOGUE
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push %edx /* push a copy for us */
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push %edx /* push a copy as function argument */
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call PIC_PLT(_C_LABEL(setuctx)) /* setuctx(ucp) */
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pop %edx /* clean up stack */
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pop %edx /* clean up stack and restore edx */
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PIC_EPILOGUE
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5: /* Restore the registers (except EAX and EDX) */
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mov CX(%edx), %ecx /* Restore ECX */
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mov BX(%edx), %ebx /* Restore EBX */
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mov DI(%edx), %edi /* Restore EDI */
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mov SI(%edx), %esi /* Restore ESI */
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mov BP(%edx), %ebp /* Restore EBP */
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mov SP(%edx), %esp /* Restore stack pointer */
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xor %eax, %eax /* Return 0 */
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jmp *PC(%edx) /* Return to RTA */
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/* void ctx_start((void *func)(int arg1, ..., argn), arg1, ..., argn,
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* ucontext_t *ucp)
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* A wrapper to start function `func'. ESI register will contain a pointer
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* to ucp on the stack. By setting ESP to ESI, we effectively 'remove' all
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* arguments to `func' from the stack. Finally, a call to resumecontext
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* will start the next context in the linked list (or exit the program if
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* there is no context).
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*
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* Since PIC needs the EBX register, which is pushed on the stack by
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* PIC_PROLOGUE, we need an extra of salsa here.
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*/
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ENTRY(ctx_start)
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/* 0(esp) -> func
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* 4(esp) -> arg1
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* ...
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* 4*n(esp) -> argn
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* 4*(n+1)(esp) -> ucp */
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pop %eax /* eax = func */
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call *%eax /* func(arg1, ..., argn) */
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PIC_PROLOGUE /* may push %ebx, but we do not care */
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mov %esi, %esp /* Clean up stack, keep %ebx = &GOT */
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/* ucp is now at the top of the stack again */
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call PIC_PLT(_C_LABEL(resumecontext)) /* resumecontext(ucp) */
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ret /* never reached */
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