211 lines
5.7 KiB
ArmAsm
211 lines
5.7 KiB
ArmAsm
#include <machine/asm.h>
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#ifdef __ACK__
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.text
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begtext:
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#ifdef __ACK__
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.rom
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#else
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.data
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#endif
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begrom:
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.data
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begdata:
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.bss
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begbss:
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#endif
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IMPORT(getuctx)
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IMPORT(setuctx)
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IMPORT(resumecontext)
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/* Offsets into ucontext_t structure. Keep in sync with <sys/ucontext.h>! */
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#define UC_FLAGS 0
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#define UC_LINK UC_FLAGS + 4
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#define MCTX UC_LINK + 4
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#define MAGIC MCTX
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#define GS MAGIC+4
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#define FS GS+2
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#define ES FS+2
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#define DS ES+2
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#define DI DS+2
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#define SI DI+4
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#define BP SI+4
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#define ST BP+4 /* Hole for another SP */
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#define BX ST+4
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#define DX BX+4
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#define CX DX+4
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#define AX CX+4
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#define RETADR AX+4
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#define PC RETADR+4
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#define CS PC+4
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#define PSW CS+4
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#define SP PSW+4
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#define SS SP+4
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/* MCF_MAGIC value from <mcontext.h> */
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#define MCF_MAGIC 0xc0ffee
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/* Values from <sys/ucontext.h> */
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#define UCF_IGNFPU 0x002
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#define UCF_IGNSIGM 0x004
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/* EINVAL from errno.h */
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#define EFAULT 14
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#define EINVAL 22
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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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/* 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 (%esp), %ecx /* Save return address:
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* When setcontext or swapcontext is called,
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* we jump to this address and continue
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* running. */
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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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movl $EFAULT, (_C_LABEL(errno))
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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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push %ecx /* save ecx */
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push %ebx /* save ebx */
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lea UC_FLAGS(%edx), %ebx /* ebx = &(ucp->uc_flags) */
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mov (%ebx), %ecx /* ecx = ucp->uc_flags */
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mov $UCF_IGNFPU, %eax
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or $UCF_IGNSIGM, %eax
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cmp %eax, %ecx /* is UCF_IGNFPU or UCF_IGNSIGM set? */
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pop %ebx /* restore ebx */
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pop %ecx /* restore ecx */
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jz 1f /* Both are set, skip getuctx */
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0:
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push %ecx /* Save ecx */
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push %edx
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call _C_LABEL(getuctx) /* getuctx(ucp) */
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pop %edx /* clean up stack and restore edx */
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pop %ecx /* Restore ecx */
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1:
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/* Save the context */
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mov 4(%esp), %edx /* edx = ucp */
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pop %eax /* retaddr */
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mov %eax, 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 */
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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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push %eax /* Restore retaddr */
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xor %eax, %eax /* Return 0 */
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2:
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add $4, %esp /* Remove stale (setcontext) RTA */
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jmp *%ecx /* Restore 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, (_C_LABEL(errno))
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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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push %ebx /* save ebx */
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lea MAGIC(%edx), %ebx /* ebx = &(ucp->mc_context.mc_magic) */
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mov (%ebx), %ecx /* ecx = ucp->mc_context.mc_magic */
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pop %ebx /* restore ebx */
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cmp $MCF_MAGIC, %ecx /* is the magic value set (is context valid)?*/
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jz 4f /* is set, proceed */
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movl $EINVAL, (_C_LABEL(errno)) /* not set, return error code */
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xor %eax, %eax
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dec %eax /* return -1 */
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ret
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4: push %ebx /* save ebx */
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lea UC_FLAGS(%edx), %ebx /* ebx = &(ucp->uc_flags) */
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mov (%ebx), %ecx /* ecx = ucp->uc_flags */
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pop %ebx /* restore ebx */
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mov $UCF_IGNFPU, %eax
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or $UCF_IGNSIGM, %eax
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cmp %eax, %ecx /* Are UCF_IGNFPU and UCF_IGNSIGM flags set? */
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jz 1f /* Both are set, so don't bother restoring FPU
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* state and signal mask */
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0: push %ecx /* Save ecx */
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push %edx
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call _C_LABEL(setuctx) /* setuctx(ucp) */
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pop %edx /* Clean up stack and restore edx */
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pop %ecx /* Restore ecx */
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1: /* Restore the registers */
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mov 4(%esp), %edx /* edx = ucp */
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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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2:
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jmp *PC(%edx) /* Push RTA onto stack so we can return to it */
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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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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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mov %esi, %esp /* Clean up stack */
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/* ucp is now at the top of the stack again */
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call _C_LABEL(resumecontext) /* resumecontext(ucp) */
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ret /* never reached */
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