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lib: sbi: Do not override emulator callback for vector load/store

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It's wrong to override the emulator callback in sbi_trap_emulate_load/
store. The function must respect the callback function passed in the
parameter. Hence, let the misaligned emulator callback decide when to
use sbi_misaligned_v_ld/st_emulator. To clean up things, also make the
following changes:

- Add the `insn` parameter to the callback. The trapping insn has been
  fetched by the caller already, whether transformed or directly loaded,
  thus saving the trouble in the callback. Note that you must not rely
  on the length of the `insn`, as it can be a transformed one from tinst

- Also the `tcntx` is added, providing the callback with register values
  to handle vector insn or other customized insns.

- Clarify that the read/write length (rlen/wlen) can be 0, in which
  case it could be a vector load/store or some customized instruction.
  The callback is responsible to handle it accordingly.

Also fixed issues in the sbi_misaligned_v_ld/st_emulator:
a. Redirect the trap when OPENSBI_CC_SUPPORT_VECTOR is not available.
b. Ensure the return code is >0 when no faults are redirected.

Fixes: c2acc5e5b0 ("lib: sbi_misaligned_ldst: Add handling of vector load/store")
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anirudh Srinivasan <asrinivasan@oss.tenstorrent.com>
Link: https://lore.kernel.org/r/20260605113214.242-6-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Bo Gan
2026-06-05 04:32:11 -07:00
committed by Anup Patel
parent 7dfaa46782
commit eba121b459
4 changed files with 137 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/sbi/sbi_trap_ldst.c
+62 -38
View File
@@ -18,18 +18,18 @@
/**
* Load emulator callback:
*
* @return rlen=success, 0=success w/o regs modification, or negative error
* Refer to comments of `sbi_platform_emulate_load`.
*/
typedef int (*sbi_trap_ld_emulator)(int rlen, union sbi_ldst_data *out_val,
typedef int (*sbi_trap_ld_emulator)(ulong insn, int rlen, ulong raddr,
union sbi_ldst_data *out_val,
struct sbi_trap_context *tcntx);
/**
* Store emulator callback:
*
* @return wlen=success, 0=success w/o regs modification, or negative error
* Refer to comments of `sbi_platform_emulate_store`.
*/
typedef int (*sbi_trap_st_emulator)(int wlen, union sbi_ldst_data in_val,
typedef int (*sbi_trap_st_emulator)(ulong insn, int wlen, ulong waddr,
union sbi_ldst_data in_val,
struct sbi_trap_context *tcntx);
ulong sbi_misaligned_tinst_fixup(ulong orig_tinst, ulong new_tinst,
@@ -52,7 +52,7 @@ static int sbi_trap_emulate_load(struct sbi_trap_context *tcntx,
ulong insn, insn_len;
union sbi_ldst_data val = { 0 };
struct sbi_trap_info uptrap;
int rc, fp = 0, shift = 0, len = 0, vector = 0;
int rc, fp = 0, shift = 0, len = 0;
if (orig_trap->tinst & 0x1) {
/*
@@ -144,28 +144,24 @@ static int sbi_trap_emulate_load(struct sbi_trap_context *tcntx,
len = 2;
shift = 8 * (sizeof(ulong) - len);
insn = RVC_RS2S(insn) << SH_RD;
} else if (IS_VECTOR_LOAD_STORE(insn)) {
vector = 1;
emu = sbi_misaligned_v_ld_emulator;
} else {
return sbi_trap_redirect(regs, orig_trap);
}
rc = emu(len, &val, tcntx);
rc = emu(insn, len, orig_trap->tval, &val, tcntx);
if (rc <= 0)
return rc;
if (!len)
goto epc_fixup;
if (!vector) {
if (!fp)
SET_RD(insn, regs, ((long)(val.data_ulong << shift)) >> shift);
if (!fp)
SET_RD(insn, regs, ((long)(val.data_ulong << shift)) >> shift);
#ifdef __riscv_flen
else if (len == 8)
SET_F64_RD(insn, regs, val.data_u64);
else
SET_F32_RD(insn, regs, val.data_ulong);
else if (len == 8)
SET_F64_RD(insn, regs, val.data_u64);
else
SET_F32_RD(insn, regs, val.data_ulong);
#endif
}
epc_fixup:
regs->mepc += insn_len;
return 0;
@@ -253,13 +249,9 @@ static int sbi_trap_emulate_store(struct sbi_trap_context *tcntx,
} else if ((insn & INSN_MASK_C_SH) == INSN_MATCH_C_SH) {
len = 2;
val.data_ulong = GET_RS2S(insn, regs);
} else if (IS_VECTOR_LOAD_STORE(insn)) {
emu = sbi_misaligned_v_st_emulator;
} else {
return sbi_trap_redirect(regs, orig_trap);
}
rc = emu(len, val, tcntx);
rc = emu(insn, len, orig_trap->tval, val, tcntx);
if (rc <= 0)
return rc;
@@ -268,7 +260,8 @@ static int sbi_trap_emulate_store(struct sbi_trap_context *tcntx,
return 0;
}
static int sbi_misaligned_ld_emulator(int rlen, union sbi_ldst_data *out_val,
static int sbi_misaligned_ld_emulator(ulong insn, int rlen, ulong addr,
union sbi_ldst_data *out_val,
struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
@@ -276,9 +269,20 @@ static int sbi_misaligned_ld_emulator(int rlen, union sbi_ldst_data *out_val,
struct sbi_trap_info uptrap;
int i;
if (!rlen) {
if (IS_VECTOR_LOAD_STORE(insn))
return sbi_misaligned_v_ld_emulator(insn, tcntx);
else
/* Unrecognized instruction. Can't emulate it. */
return sbi_trap_redirect(regs, orig_trap);
}
/* For misaligned fault, addr must be the same as orig_trap->tval */
if (addr != orig_trap->tval)
return SBI_EFAIL;
for (i = 0; i < rlen; i++) {
out_val->data_bytes[i] =
sbi_load_u8((void *)(orig_trap->tval + i), &uptrap);
sbi_load_u8((void *)(addr + i), &uptrap);
if (uptrap.cause) {
uptrap.tinst = sbi_misaligned_tinst_fixup(
orig_trap->tinst, uptrap.tinst, i);
@@ -293,7 +297,8 @@ int sbi_misaligned_load_handler(struct sbi_trap_context *tcntx)
return sbi_trap_emulate_load(tcntx, sbi_misaligned_ld_emulator);
}
static int sbi_misaligned_st_emulator(int wlen, union sbi_ldst_data in_val,
static int sbi_misaligned_st_emulator(ulong insn, int wlen, ulong addr,
union sbi_ldst_data in_val,
struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
@@ -301,8 +306,19 @@ static int sbi_misaligned_st_emulator(int wlen, union sbi_ldst_data in_val,
struct sbi_trap_info uptrap;
int i;
if (!wlen) {
if (IS_VECTOR_LOAD_STORE(insn))
return sbi_misaligned_v_st_emulator(insn, tcntx);
else
/* Unrecognized instruction. Can't emulate it. */
return sbi_trap_redirect(regs, orig_trap);
}
/* For misaligned fault, addr must be the same as orig_trap->tval */
if (addr != orig_trap->tval)
return SBI_EFAIL;
for (i = 0; i < wlen; i++) {
sbi_store_u8((void *)(orig_trap->tval + i),
sbi_store_u8((void *)(addr + i),
in_val.data_bytes[i], &uptrap);
if (uptrap.cause) {
uptrap.tinst = sbi_misaligned_tinst_fixup(
@@ -318,22 +334,26 @@ int sbi_misaligned_store_handler(struct sbi_trap_context *tcntx)
return sbi_trap_emulate_store(tcntx, sbi_misaligned_st_emulator);
}
static int sbi_ld_access_emulator(int rlen, union sbi_ldst_data *out_val,
static int sbi_ld_access_emulator(ulong insn, int rlen, ulong addr,
union sbi_ldst_data *out_val,
struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
int rc;
/* If fault came from M mode, just fail */
if (sbi_mstatus_prev_mode(regs->mstatus) == PRV_M)
return SBI_EINVAL;
rc = sbi_platform_emulate_load(sbi_platform_thishart_ptr(),
insn, rlen, addr, out_val, tcntx);
/* If platform emulator failed, we redirect instead of fail */
if (sbi_platform_emulate_load(sbi_platform_thishart_ptr(), rlen,
orig_trap->tval, out_val))
if (rc < 0)
return sbi_trap_redirect(regs, orig_trap);
return rlen;
return rc;
}
int sbi_load_access_handler(struct sbi_trap_context *tcntx)
@@ -341,22 +361,26 @@ int sbi_load_access_handler(struct sbi_trap_context *tcntx)
return sbi_trap_emulate_load(tcntx, sbi_ld_access_emulator);
}
static int sbi_st_access_emulator(int wlen, union sbi_ldst_data in_val,
static int sbi_st_access_emulator(ulong insn, int wlen, ulong addr,
union sbi_ldst_data in_val,
struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
int rc;
/* If fault came from M mode, just fail */
if (sbi_mstatus_prev_mode(regs->mstatus) == PRV_M)
return SBI_EINVAL;
rc = sbi_platform_emulate_store(sbi_platform_thishart_ptr(),
insn, wlen, addr, in_val, tcntx);
/* If platform emulator failed, we redirect instead of fail */
if (sbi_platform_emulate_store(sbi_platform_thishart_ptr(), wlen,
orig_trap->tval, in_val))
if (rc < 0)
return sbi_trap_redirect(regs, orig_trap);
return wlen;
return rc;
}
int sbi_store_access_handler(struct sbi_trap_context *tcntx)
lib/sbi/sbi_trap_v_ldst.c
+9 -12
View File
@@ -137,13 +137,11 @@ static inline void vsetvl(ulong vl, ulong vtype)
:: "r" (vl), "r" (vtype));
}
int sbi_misaligned_v_ld_emulator(int rlen, union sbi_ldst_data *out_val,
struct sbi_trap_context *tcntx)
int sbi_misaligned_v_ld_emulator(ulong insn, struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
struct sbi_trap_info uptrap;
ulong insn = sbi_get_insn(regs->mepc, &uptrap);
ulong vl = csr_read(CSR_VL);
ulong vtype = csr_read(CSR_VTYPE);
ulong vlenb = csr_read(CSR_VLENB);
@@ -234,16 +232,15 @@ int sbi_misaligned_v_ld_emulator(int rlen, union sbi_ldst_data *out_val,
/* restore clobbered vl/vtype */
vsetvl(vl, vtype);
return vl;
/* Return a >0 value for the caller to advance mepc */
return 1;
}
int sbi_misaligned_v_st_emulator(int wlen, union sbi_ldst_data in_val,
struct sbi_trap_context *tcntx)
int sbi_misaligned_v_st_emulator(ulong insn, struct sbi_trap_context *tcntx)
{
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
struct sbi_trap_info uptrap;
ulong insn = sbi_get_insn(regs->mepc, &uptrap);
ulong vl = csr_read(CSR_VL);
ulong vtype = csr_read(CSR_VTYPE);
ulong vlenb = csr_read(CSR_VLENB);
@@ -328,17 +325,17 @@ int sbi_misaligned_v_st_emulator(int wlen, union sbi_ldst_data in_val,
/* restore clobbered vl/vtype */
vsetvl(vl, vtype);
return vl;
/* Return a >0 value for the caller to advance mepc */
return 1;
}
#else
int sbi_misaligned_v_ld_emulator(int rlen, union sbi_ldst_data *out_val,
struct sbi_trap_context *tcntx)
int sbi_misaligned_v_ld_emulator(ulong insn, struct sbi_trap_context *tcntx)
{
/* Unable to emulate, send trap to previous mode. */
return sbi_trap_redirect(&tcntx->regs, &tcntx->trap);
}
int sbi_misaligned_v_st_emulator(int wlen, union sbi_ldst_data in_val,
struct sbi_trap_context *tcntx)
int sbi_misaligned_v_st_emulator(ulong insn, struct sbi_trap_context *tcntx)
{
/* Unable to emulate, send trap to previous mode. */
return sbi_trap_redirect(&tcntx->regs, &tcntx->trap);