44 lines
1.9 KiB
ArmAsm
44 lines
1.9 KiB
ArmAsm
#include "tx_port.h"
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.section .text
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.align 2
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.global _tx_thread_smp_protect
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.type _tx_thread_smp_protect, @function
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_tx_thread_smp_protect:
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/* Disable interrupts so we don't get preempted. */
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csrr a0, mstatus // Pickup current interrupt posture
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csrci mstatus, 0x08 // Lockout interrupts
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/* Pickup the hart ID. */
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csrr t2, mhartid // Pickup the current hart ID
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/* Build address to protection structure. */
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la t1, _tx_thread_smp_protection
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/* If this hart already owns protection, just nest the count. */
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LOAD t3, 1*REGBYTES(t1) // Pickup owning hart
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beq t3, t2, _owned // Already owned by this hart
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/* Try to get the protection. */
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LOAD t4, 0(t1) // Pickup protection flag
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bnez t4, _protection_busy // If set, protection is busy
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li t4, 1 // Build lock value
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AMOSWAP_AQ t5, t4, (t1) // Attempt to get protection
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bnez t5, _protection_busy // If old value != 0, retry
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fence rw, rw // Ensure lock acquisition is visible
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STORE t2, 1*REGBYTES(t1) // Save owning hart
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_owned:
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LOAD t5, 2*REGBYTES(t1) // Pickup ownership count
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addi t5, t5, 1 // Increment ownership count
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STORE t5, 2*REGBYTES(t1) // Store ownership count
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fence rw, rw // Publish owner/count before return
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ret
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_protection_busy:
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csrw mstatus, a0 // Restore interrupts
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j _tx_thread_smp_protect // Restart the protection attempt
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