158 lines
4.6 KiB
ArmAsm
158 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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/* 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 r3, lr /* 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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/* r0 = ucp */
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/* Check null pointer */
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cmp r0, #0 /* ucp == NULL? */
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bne 3f /* Not null, continue */
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mov r1, #EFAULT
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ldr r2, =_C_LABEL(errno)
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str r1, [r2] /* errno = EFAULT */
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mov r0, #-1 /* return -1 */
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bx lr
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3: /* Check flags */
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ldr r1, [r0, #UC_FLAGS] /* r1 = ucp->uc_flags */
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mov r2, #(UCF_IGNFPU | UCF_IGNSIGM)
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cmp r1, r2 /* is UCF_IGNFPU or UCF_IGNSIGM set? */
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beq 1f /* Both are set, skip getuctx */
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0:
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push {r0, r3}
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bl _C_LABEL(getuctx) /* getuctx(ucp) */
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pop {r0, r3}
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1:
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/* Save the context */
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mov lr, r3 /* Restore lr */
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str lr, [r0, #LRREG] /* Save lr */
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str lr, [r0, #PCREG] /* Save real RTA in mcp struct */
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str sp, [r0, #SPREG] /* Save stack pointer */
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str fp, [r0, #FPREG] /* Save fp */
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str r4, [r0, #REG4] /* Save r4 */
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str r5, [r0, #REG5] /* Save r5 */
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str r6, [r0, #REG6] /* Save r6 */
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str r7, [r0, #REG7] /* Save r7 */
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str r8, [r0, #REG8] /* Save r8 */
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str r9, [r0, #REG9] /* Save r9 */
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str r10, [r0, #REG10] /* Save r10 */
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ldr r1, =MCF_MAGIC
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str r1, [r0, #MAGIC] /* Set magic value */
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mov r1, #0
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str r1, [r0, #REG0] /* Return 0 */
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mov r0, #0 /* Return 0 */
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2:
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bx lr /* 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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/* r0 = ucp */
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/* Check null pointer */
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cmp r0, #0 /* ucp == NULL? */
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bne 3f /* Not null, continue */
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mov r1, #EFAULT
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ldr r2, =_C_LABEL(errno)
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str r1, [r2] /* errno = EFAULT */
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mov r0, #-1 /* return -1 */
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bx lr
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3: /* Check flags */
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ldr r1, [r0, #MAGIC] /* r1 = ucp->mc_context.mc_magic */
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ldr r2, =MCF_MAGIC
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cmp r1, r2 /* is the magic value set (is context valid)?*/
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beq 4f /* is set, proceed */
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mov r1, #EINVAL /* not set, return error code */
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ldr r2, =_C_LABEL(errno)
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str r1, [r2] /* errno = EINVAL */
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mov r0, #-1 /* return -1 */
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bx lr
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4: ldr r1, [r0, #UC_FLAGS] /* r1 = ucp->uc_flags */
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mov r2, #(UCF_IGNFPU | UCF_IGNSIGM)
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cmp r1, r2 /* Are UCF_IGNFPU and UCF_IGNSIGM flags set? */
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beq 1f /* Both are set, so don't bother restoring FPU
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* state and signal mask */
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push {r0, r3}
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0: bl _C_LABEL(setuctx) /* setuctx(ucp) */
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pop {r0, r3}
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1: /* Restore the registers */
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ldr r1, [r0, #REG1] /* Restore r1 */
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ldr r2, [r0, #REG2] /* Restore r2 */
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ldr r3, [r0, #REG3] /* Restore r3 */
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ldr r4, [r0, #REG4] /* Restore r4 */
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ldr r5, [r0, #REG5] /* Restore r5 */
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ldr r6, [r0, #REG6] /* Restore r6 */
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ldr r7, [r0, #REG7] /* Restore r7 */
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ldr r8, [r0, #REG8] /* Restore r8 */
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ldr r9, [r0, #REG9] /* Restore r9 */
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ldr r10, [r0, #REG10] /* Restore r10 */
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ldr r12, [r0, #REG12] /* Restore r12 */
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ldr fp, [r0, #FPREG] /* Restore fp */
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ldr sp, [r0, #SPREG] /* Restore sp */
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ldr lr, [r0, #LRREG] /* Restore lr */
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mov r4, r0
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ldr r0, [r4, #REG0] /* Restore r0 */
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2:
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ldr pc, [r4, #PCREG] /* Restore pc */
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/* void ctx_start()
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* A wrapper to call resumecontext. Makecontext puts the ucp in r4.
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* This function moves the ucp into r0 so that the ucp is the first
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* parameter for resumecontext. The call to resumecontext will start
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* the next context in the linked list (or exit the program if there
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* is no context). */
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ENTRY(ctx_start)
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mov r0, r4
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b _C_LABEL(resumecontext)
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