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opensbi/lib/sbi/sbi_trap.c
dramforever adc3388d76 lib: sbi_trap: Redirect exception based on hedeleg 
HS-mode software can choose what exceptions to delegate to VS-mode using
the hedeleg CSR. Synthetic VS/VU-mode exceptions should also honor
hedeleg. They should be redirected to VS-mode if and only if delegated
by HS-mode.

Signed-off-by: dramforever <dramforever@live.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
2022-06-13 11:02:49 +05:30

342 lines
9.8 KiB
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/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2019 Western Digital Corporation or its affiliates.
*
* Authors:
* Anup Patel <anup.patel@wdc.com>
*/
#include <sbi/riscv_asm.h>
#include <sbi/riscv_encoding.h>
#include <sbi/sbi_console.h>
#include <sbi/sbi_ecall.h>
#include <sbi/sbi_error.h>
#include <sbi/sbi_hart.h>
#include <sbi/sbi_illegal_insn.h>
#include <sbi/sbi_ipi.h>
#include <sbi/sbi_irqchip.h>
#include <sbi/sbi_misaligned_ldst.h>
#include <sbi/sbi_pmu.h>
#include <sbi/sbi_scratch.h>
#include <sbi/sbi_timer.h>
#include <sbi/sbi_trap.h>
static void __noreturn sbi_trap_error(const char *msg, int rc,
ulong mcause, ulong mtval, ulong mtval2,
ulong mtinst, struct sbi_trap_regs *regs)
{
u32 hartid = current_hartid();
sbi_printf("%s: hart%d: %s (error %d)\n", __func__, hartid, msg, rc);
sbi_printf("%s: hart%d: mcause=0x%" PRILX " mtval=0x%" PRILX "\n",
__func__, hartid, mcause, mtval);
if (misa_extension('H')) {
sbi_printf("%s: hart%d: mtval2=0x%" PRILX
" mtinst=0x%" PRILX "\n",
__func__, hartid, mtval2, mtinst);
}
sbi_printf("%s: hart%d: mepc=0x%" PRILX " mstatus=0x%" PRILX "\n",
__func__, hartid, regs->mepc, regs->mstatus);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "ra", regs->ra, "sp", regs->sp);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "gp", regs->gp, "tp", regs->tp);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s0", regs->s0, "s1", regs->s1);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "a0", regs->a0, "a1", regs->a1);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "a2", regs->a2, "a3", regs->a3);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "a4", regs->a4, "a5", regs->a5);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "a6", regs->a6, "a7", regs->a7);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s2", regs->s2, "s3", regs->s3);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s4", regs->s4, "s5", regs->s5);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s6", regs->s6, "s7", regs->s7);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s8", regs->s8, "s9", regs->s9);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "s10", regs->s10, "s11", regs->s11);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "t0", regs->t0, "t1", regs->t1);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "t2", regs->t2, "t3", regs->t3);
sbi_printf("%s: hart%d: %s=0x%" PRILX " %s=0x%" PRILX "\n", __func__,
hartid, "t4", regs->t4, "t5", regs->t5);
sbi_printf("%s: hart%d: %s=0x%" PRILX "\n", __func__, hartid, "t6",
regs->t6);
sbi_hart_hang();
}
/**
* Redirect trap to lower privledge mode (S-mode or U-mode)
*
* @param regs pointer to register state
* @param trap pointer to trap details
*
* @return 0 on success and negative error code on failure
*/
int sbi_trap_redirect(struct sbi_trap_regs *regs,
struct sbi_trap_info *trap)
{
ulong hstatus, vsstatus, prev_mode;
#if __riscv_xlen == 32
bool prev_virt = (regs->mstatusH & MSTATUSH_MPV) ? TRUE : FALSE;
#else
bool prev_virt = (regs->mstatus & MSTATUS_MPV) ? TRUE : FALSE;
#endif
/* By default, we redirect to HS-mode */
bool next_virt = FALSE;
/* Sanity check on previous mode */
prev_mode = (regs->mstatus & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT;
if (prev_mode != PRV_S && prev_mode != PRV_U)
return SBI_ENOTSUPP;
/* If exceptions came from VS/VU-mode, redirect to VS-mode if
* delegated in hedeleg
*/
if (misa_extension('H') && prev_virt) {
if ((trap->cause < __riscv_xlen) &&
(csr_read(CSR_HEDELEG) & BIT(trap->cause))) {
next_virt = TRUE;
}
}
/* Update MSTATUS MPV bits */
#if __riscv_xlen == 32
regs->mstatusH &= ~MSTATUSH_MPV;
regs->mstatusH |= (next_virt) ? MSTATUSH_MPV : 0UL;
#else
regs->mstatus &= ~MSTATUS_MPV;
regs->mstatus |= (next_virt) ? MSTATUS_MPV : 0UL;
#endif
/* Update HSTATUS for VS/VU-mode to HS-mode transition */
if (misa_extension('H') && prev_virt && !next_virt) {
/* Update HSTATUS SPVP and SPV bits */
hstatus = csr_read(CSR_HSTATUS);
hstatus &= ~HSTATUS_SPVP;
hstatus |= (prev_mode == PRV_S) ? HSTATUS_SPVP : 0;
hstatus &= ~HSTATUS_SPV;
hstatus |= (prev_virt) ? HSTATUS_SPV : 0;
csr_write(CSR_HSTATUS, hstatus);
csr_write(CSR_HTVAL, trap->tval2);
csr_write(CSR_HTINST, trap->tinst);
}
/* Update exception related CSRs */
if (next_virt) {
/* Update VS-mode exception info */
csr_write(CSR_VSTVAL, trap->tval);
csr_write(CSR_VSEPC, trap->epc);
csr_write(CSR_VSCAUSE, trap->cause);
/* Set MEPC to VS-mode exception vector base */
regs->mepc = csr_read(CSR_VSTVEC);
/* Set MPP to VS-mode */
regs->mstatus &= ~MSTATUS_MPP;
regs->mstatus |= (PRV_S << MSTATUS_MPP_SHIFT);
/* Get VS-mode SSTATUS CSR */
vsstatus = csr_read(CSR_VSSTATUS);
/* Set SPP for VS-mode */
vsstatus &= ~SSTATUS_SPP;
if (prev_mode == PRV_S)
vsstatus |= (1UL << SSTATUS_SPP_SHIFT);
/* Set SPIE for VS-mode */
vsstatus &= ~SSTATUS_SPIE;
if (vsstatus & SSTATUS_SIE)
vsstatus |= (1UL << SSTATUS_SPIE_SHIFT);
/* Clear SIE for VS-mode */
vsstatus &= ~SSTATUS_SIE;
/* Update VS-mode SSTATUS CSR */
csr_write(CSR_VSSTATUS, vsstatus);
} else {
/* Update S-mode exception info */
csr_write(CSR_STVAL, trap->tval);
csr_write(CSR_SEPC, trap->epc);
csr_write(CSR_SCAUSE, trap->cause);
/* Set MEPC to S-mode exception vector base */
regs->mepc = csr_read(CSR_STVEC);
/* Set MPP to S-mode */
regs->mstatus &= ~MSTATUS_MPP;
regs->mstatus |= (PRV_S << MSTATUS_MPP_SHIFT);
/* Set SPP for S-mode */
regs->mstatus &= ~MSTATUS_SPP;
if (prev_mode == PRV_S)
regs->mstatus |= (1UL << MSTATUS_SPP_SHIFT);
/* Set SPIE for S-mode */
regs->mstatus &= ~MSTATUS_SPIE;
if (regs->mstatus & MSTATUS_SIE)
regs->mstatus |= (1UL << MSTATUS_SPIE_SHIFT);
/* Clear SIE for S-mode */
regs->mstatus &= ~MSTATUS_SIE;
}
return 0;
}
static int sbi_trap_nonaia_irq(struct sbi_trap_regs *regs, ulong mcause)
{
mcause &= ~(1UL << (__riscv_xlen - 1));
switch (mcause) {
case IRQ_M_TIMER:
sbi_timer_process();
break;
case IRQ_M_SOFT:
sbi_ipi_process();
break;
case IRQ_M_EXT:
return sbi_irqchip_process(regs);
default:
return SBI_ENOENT;
};
return 0;
}
static int sbi_trap_aia_irq(struct sbi_trap_regs *regs, ulong mcause)
{
int rc;
unsigned long mtopi;
while ((mtopi = csr_read(CSR_MTOPI))) {
mtopi = mtopi >> TOPI_IID_SHIFT;
switch (mtopi) {
case IRQ_M_TIMER:
sbi_timer_process();
break;
case IRQ_M_SOFT:
sbi_ipi_process();
break;
case IRQ_M_EXT:
rc = sbi_irqchip_process(regs);
if (rc)
return rc;
break;
default:
return SBI_ENOENT;
}
}
return 0;
}
/**
* Handle trap/interrupt
*
* This function is called by firmware linked to OpenSBI
* library for handling trap/interrupt. It expects the
* following:
* 1. The 'mscratch' CSR is pointing to sbi_scratch of current HART
* 2. The 'mcause' CSR is having exception/interrupt cause
* 3. The 'mtval' CSR is having additional trap information
* 4. The 'mtval2' CSR is having additional trap information
* 5. The 'mtinst' CSR is having decoded trap instruction
* 6. Stack pointer (SP) is setup for current HART
* 7. Interrupts are disabled in MSTATUS CSR
*
* @param regs pointer to register state
*/
struct sbi_trap_regs *sbi_trap_handler(struct sbi_trap_regs *regs)
{
int rc = SBI_ENOTSUPP;
const char *msg = "trap handler failed";
ulong mcause = csr_read(CSR_MCAUSE);
ulong mtval = csr_read(CSR_MTVAL), mtval2 = 0, mtinst = 0;
struct sbi_trap_info trap;
if (misa_extension('H')) {
mtval2 = csr_read(CSR_MTVAL2);
mtinst = csr_read(CSR_MTINST);
}
if (mcause & (1UL << (__riscv_xlen - 1))) {
if (sbi_hart_has_extension(sbi_scratch_thishart_ptr(),
SBI_HART_EXT_AIA))
rc = sbi_trap_aia_irq(regs, mcause);
else
rc = sbi_trap_nonaia_irq(regs, mcause);
if (rc) {
msg = "unhandled local interrupt";
goto trap_error;
}
return regs;
}
switch (mcause) {
case CAUSE_ILLEGAL_INSTRUCTION:
rc = sbi_illegal_insn_handler(mtval, regs);
msg = "illegal instruction handler failed";
break;
case CAUSE_MISALIGNED_LOAD:
rc = sbi_misaligned_load_handler(mtval, mtval2, mtinst, regs);
msg = "misaligned load handler failed";
break;
case CAUSE_MISALIGNED_STORE:
rc = sbi_misaligned_store_handler(mtval, mtval2, mtinst, regs);
msg = "misaligned store handler failed";
break;
case CAUSE_SUPERVISOR_ECALL:
case CAUSE_MACHINE_ECALL:
rc = sbi_ecall_handler(regs);
msg = "ecall handler failed";
break;
case CAUSE_LOAD_ACCESS:
case CAUSE_STORE_ACCESS:
sbi_pmu_ctr_incr_fw(mcause == CAUSE_LOAD_ACCESS ?
SBI_PMU_FW_ACCESS_LOAD : SBI_PMU_FW_ACCESS_STORE);
/* fallthrough */
default:
/* If the trap came from S or U mode, redirect it there */
trap.epc = regs->mepc;
trap.cause = mcause;
trap.tval = mtval;
trap.tval2 = mtval2;
trap.tinst = mtinst;
rc = sbi_trap_redirect(regs, &trap);
break;
};
trap_error:
if (rc)
sbi_trap_error(msg, rc, mcause, mtval, mtval2, mtinst, regs);
return regs;
}
typedef void (*trap_exit_t)(const struct sbi_trap_regs *regs);
/**
* Exit trap/interrupt handling
*
* This function is called by non-firmware code to abruptly exit
* trap/interrupt handling and resume execution at context pointed
* by given register state.
*
* @param regs pointer to register state
*/
void __noreturn sbi_trap_exit(const struct sbi_trap_regs *regs)
{
struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
((trap_exit_t)scratch->trap_exit)(regs);
__builtin_unreachable();
}
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