forked from Mirrors/opensbi
897a97a6af
Linux kernel expects tlb flush SBI call to be completely synchronous i.e. the SBI call should only return once corresponding *fence* instruction is executed. OpenSBI manages the outstanding TLB flush requests by keeping them in a per hart based fifo. However, there are few corner cases that may lead to race conditions while updating the fifo. Currently, the caller hart waits for IPI acknowledgement via clint address which is not a very good method as synchronization on MMIO may not be supported in every platform. Moreover, the waiter doesn't have any way of identifying if the IPI is received for specific tlb flush request or any other IPI. This may lead to unpredictable behavior in supervisor/user space. Fix this by waiting on individual fifo entries rather than MMIO address. Currently, a relaxed loop is being used because wfi again involves MMIO write which would be slower compared to relaxed loop. To avoid deadlock, fifo is processed every time a hart loops for fifo enqueue or fifo sync to consume the tlb flush requests sent by other harts. Signed-off-by: Anup Patel <anup.patel@wdc.com> Signed-off-by: Atish Patra <atish.patra@wdc.com>
116 lines
2.7 KiB
C
116 lines
2.7 KiB
C
/*
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Western Digital Corporation or its affiliates.
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*
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* Authors:
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* Anup Patel <anup.patel@wdc.com>
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*/
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#include <sbi/sbi_console.h>
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#include <sbi/sbi_ecall.h>
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#include <sbi/sbi_ecall_interface.h>
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#include <sbi/sbi_error.h>
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#include <sbi/sbi_ipi.h>
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#include <sbi/sbi_system.h>
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#include <sbi/sbi_timer.h>
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#include <sbi/sbi_tlb.h>
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#include <sbi/sbi_trap.h>
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#include <sbi/sbi_hart.h>
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#define SBI_ECALL_VERSION_MAJOR 0
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#define SBI_ECALL_VERSION_MINOR 1
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u16 sbi_ecall_version_major(void)
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{
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return SBI_ECALL_VERSION_MAJOR;
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}
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u16 sbi_ecall_version_minor(void)
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{
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return SBI_ECALL_VERSION_MINOR;
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}
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int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
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struct sbi_scratch *scratch)
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{
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int ret = SBI_ENOTSUPP;
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struct unpriv_trap uptrap;
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struct sbi_tlb_info tlb_info;
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u32 source_hart = sbi_current_hartid();
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switch (regs->a7) {
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case SBI_ECALL_SET_TIMER:
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#if __riscv_xlen == 32
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sbi_timer_event_start(scratch,
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(((u64)regs->a1 << 32) | (u64)regs->a0));
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#else
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sbi_timer_event_start(scratch, (u64)regs->a0);
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#endif
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ret = 0;
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break;
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case SBI_ECALL_CONSOLE_PUTCHAR:
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sbi_putc(regs->a0);
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ret = 0;
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break;
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case SBI_ECALL_CONSOLE_GETCHAR:
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regs->a0 = sbi_getc();
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ret = 0;
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break;
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case SBI_ECALL_CLEAR_IPI:
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sbi_ipi_clear_smode(scratch);
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ret = 0;
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break;
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case SBI_ECALL_SEND_IPI:
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ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
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SBI_IPI_EVENT_SOFT, NULL);
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break;
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case SBI_ECALL_REMOTE_FENCE_I:
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tlb_info.start = 0;
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tlb_info.size = 0;
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tlb_info.type = SBI_ITLB_FLUSH;
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tlb_info.shart_mask = 1UL << source_hart;
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ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
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SBI_IPI_EVENT_FENCE_I, &tlb_info);
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break;
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case SBI_ECALL_REMOTE_SFENCE_VMA:
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tlb_info.start = (unsigned long)regs->a1;
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tlb_info.size = (unsigned long)regs->a2;
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tlb_info.type = SBI_TLB_FLUSH_VMA;
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tlb_info.shart_mask = 1UL << source_hart;
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ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
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SBI_IPI_EVENT_SFENCE_VMA, &tlb_info);
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break;
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case SBI_ECALL_REMOTE_SFENCE_VMA_ASID:
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tlb_info.start = (unsigned long)regs->a1;
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tlb_info.size = (unsigned long)regs->a2;
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tlb_info.asid = (unsigned long)regs->a3;
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tlb_info.type = SBI_TLB_FLUSH_VMA_ASID;
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tlb_info.shart_mask = 1UL << source_hart;
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ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
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SBI_IPI_EVENT_SFENCE_VMA_ASID,
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&tlb_info);
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break;
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case SBI_ECALL_SHUTDOWN:
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sbi_system_shutdown(scratch, 0);
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ret = 0;
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break;
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default:
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regs->a0 = SBI_ENOTSUPP;
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ret = 0;
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break;
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};
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if (!ret) {
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regs->mepc += 4;
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} else if (ret == SBI_ETRAP) {
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ret = 0;
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sbi_trap_redirect(regs, scratch, regs->mepc,
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uptrap.cause, uptrap.tval);
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}
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return ret;
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}
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