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lib: sbi: Add variable-length unprivilege access functions

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sbi_load/store_loop read/write variable-length buffer unprivileged.
Both function use the widest aligned 8/4/2/1 byte load/stores in each
loop to reduce the total number of iterations.

Also switch the scalar/vector misaligned handlers to make use of such
functions to simplify code.

Miscellaneous: remove the unnecessary [taddr] in inline assembly

Signed-off-by: Bo Gan <ganboing@gmail.com>
Tested-by: Anirudh Srinivasan <asrinivasan@oss.tenstorrent.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260609060024.706-4-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Bo Gan
2026-06-08 23:00:23 -07:00
committed by Anup Patel
parent 1475f147f6
commit 914aeddaf1
4 changed files with 122 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/sbi/sbi_unpriv.h
+6
View File
@@ -36,6 +36,12 @@ DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u64)
DECLARE_UNPRIVILEGED_STORE_FUNCTION(u64)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(ulong)
void sbi_load_loop(u8 *buffer, ulong addr, ulong len,
struct sbi_trap_info *trap);
void sbi_store_loop(u8 *buffer, ulong addr, ulong len,
struct sbi_trap_info *trap);
ulong sbi_get_insn(ulong mepc, struct sbi_trap_info *trap);
#endif
lib/sbi/sbi_trap_ldst.c
+2 -10
View File
@@ -471,7 +471,6 @@ static int sbi_misaligned_ld_emulator(ulong insn, int rlen, ulong addr,
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
struct sbi_trap_info uptrap;
int i;
if (!rlen) {
if (IS_VECTOR_LOAD_STORE(insn))
@@ -484,14 +483,11 @@ static int sbi_misaligned_ld_emulator(ulong insn, int rlen, ulong addr,
if (addr != orig_trap->tval)
return SBI_EFAIL;
for (i = 0; i < rlen; i++) {
out_val->data_bytes[i] =
sbi_load_u8((void *)(addr + i), &uptrap);
sbi_load_loop(out_val->data_bytes, addr, rlen, &uptrap);
if (uptrap.cause) {
sbi_misaligned_tinst_fixup(orig_trap, &uptrap);
return sbi_trap_redirect(regs, &uptrap);
}
}
return rlen;
}
@@ -507,7 +503,6 @@ static int sbi_misaligned_st_emulator(ulong insn, int wlen, ulong addr,
const struct sbi_trap_info *orig_trap = &tcntx->trap;
struct sbi_trap_regs *regs = &tcntx->regs;
struct sbi_trap_info uptrap;
int i;
if (!wlen) {
if (IS_VECTOR_LOAD_STORE(insn))
@@ -520,14 +515,11 @@ static int sbi_misaligned_st_emulator(ulong insn, int wlen, ulong addr,
if (addr != orig_trap->tval)
return SBI_EFAIL;
for (i = 0; i < wlen; i++) {
sbi_store_u8((void *)(addr + i),
in_val.data_bytes[i], &uptrap);
sbi_store_loop(in_val.data_bytes, addr, wlen, &uptrap);
if (uptrap.cause) {
sbi_misaligned_tinst_fixup(orig_trap, &uptrap);
return sbi_trap_redirect(regs, &uptrap);
}
}
return wlen;
}
lib/sbi/sbi_trap_v_ldst.c
+5 -9
View File
@@ -229,10 +229,8 @@ int sbi_misaligned_v_ld_emulator(ulong insn, struct sbi_trap_context *tcntx)
/* obtain load data from memory */
for (ulong seg = 0; seg < nf; seg++) {
for (ulong i = 0; i < len; i++) {
bytes[seg * len + i] =
sbi_load_u8((void *)(addr + seg * len + i),
&uptrap);
sbi_load_loop(bytes + seg * len,
addr + seg * len, len, &uptrap);
if (uptrap.cause) {
if (IS_FAULT_ONLY_FIRST_LOAD(insn) && vstart != 0) {
@@ -244,7 +242,6 @@ int sbi_misaligned_v_ld_emulator(ulong insn, struct sbi_trap_context *tcntx)
return sbi_trap_redirect(regs, &uptrap);
}
}
}
/* write load data to regfile */
for (ulong seg = 0; seg < nf; seg++)
@@ -332,16 +329,15 @@ int sbi_misaligned_v_st_emulator(ulong insn, struct sbi_trap_context *tcntx)
/* write store data to memory */
for (ulong seg = 0; seg < nf; seg++) {
for (ulong i = 0; i < len; i++) {
sbi_store_u8((void *)(addr + seg * len + i),
bytes[seg * len + i], &uptrap);
sbi_store_loop(bytes + seg * len,
addr + seg * len, len, &uptrap);
if (uptrap.cause) {
vsetvl(vl, vtype);
sbi_misaligned_v_tinst_fixup(&uptrap);
return sbi_trap_redirect(regs, &uptrap);
}
}
}
} while (++vstart < vl);
/* restore clobbered vl/vtype */
lib/sbi/sbi_unpriv.c
+92 -6
View File
@@ -11,9 +11,20 @@
#include <sbi/sbi_bitops.h>
#include <sbi/sbi_hart.h>
#include <sbi/sbi_scratch.h>
#include <sbi/sbi_string.h>
#include <sbi/sbi_trap.h>
#include <sbi/sbi_unpriv.h>
union sbi_unpriv_data {
u8 b;
u16 h;
u32 w;
#if __riscv_xlen == 64
u64 d;
#endif
u8 bytes[__riscv_xlen / 8];
};
/**
* a3 must a pointer to the sbi_trap_info and a4 is used as a temporary
* register in the trap handler. Make sure that compiler doesn't use a3 & a4.
@@ -22,13 +33,12 @@
type sbi_load_##type(const type *addr, \
struct sbi_trap_info *trap) \
{ \
register ulong tinfo asm("a3"); \
register ulong tinfo asm("a3") = (ulong)trap; \
register ulong mstatus = 0; \
register ulong mtvec = (ulong)sbi_hart_expected_trap; \
type ret = 0; \
trap->cause = 0; \
asm volatile( \
"add %[tinfo], %[taddr], zero\n" \
"csrrw %[mtvec], " STR(CSR_MTVEC) ", %[mtvec]\n" \
"csrrs %[mstatus], " STR(CSR_MSTATUS) ", %[mprv]\n" \
".option push\n" \
@@ -39,8 +49,7 @@
"csrw " STR(CSR_MTVEC) ", %[mtvec]" \
: [mstatus] "+&r"(mstatus), [mtvec] "+&r"(mtvec), \
[tinfo] "+&r"(tinfo), [ret] "=&r"(ret) \
: [addr] "m"(*addr), [mprv] "r"(MSTATUS_MPRV), \
[taddr] "r"((ulong)trap) \
: [addr] "m"(*addr), [mprv] "r"(MSTATUS_MPRV) \
: "a4", "memory"); \
return ret; \
}
@@ -54,7 +63,6 @@
register ulong mtvec = (ulong)sbi_hart_expected_trap; \
trap->cause = 0; \
asm volatile( \
"add %[tinfo], %[taddr], zero\n" \
"csrrw %[mtvec], " STR(CSR_MTVEC) ", %[mtvec]\n" \
"csrrs %[mstatus], " STR(CSR_MSTATUS) ", %[mprv]\n" \
".option push\n" \
@@ -66,7 +74,7 @@
: [mstatus] "+&r"(mstatus), [mtvec] "+&r"(mtvec), \
[tinfo] "+&r"(tinfo) \
: [addr] "m"(*addr), [mprv] "r"(MSTATUS_MPRV), \
[val] "r"(val), [taddr] "r"((ulong)trap) \
[val] "r"(val) \
: "a4", "memory"); \
}
@@ -116,6 +124,84 @@ void sbi_store_u64(u64 *addr, u64 val,
# error "Unexpected __riscv_xlen"
#endif
void sbi_load_loop(u8 *buffer, ulong addr, ulong len,
struct sbi_trap_info *trap)
{
union sbi_unpriv_data data;
trap->cause = 0;
while (len) {
unsigned int width = __riscv_xlen / 8;
void *ptr = (void*)addr;
while (len < width || (addr & (width - 1)))
width /= 2;
switch (width) {
case 1:
data.b = sbi_load_u8(ptr, trap);
break;
case 2:
data.h = sbi_load_u16(ptr, trap);
break;
case 4:
data.w = sbi_load_u32(ptr, trap);
break;
#if __riscv_xlen == 64
case 8:
data.d = sbi_load_u64(ptr, trap);
break;
#endif
}
if (trap->cause)
return;
sbi_memcpy(buffer, data.bytes, width);
len -= width;
addr += width;
buffer += width;
}
}
void sbi_store_loop(u8 *buffer, ulong addr, ulong len,
struct sbi_trap_info *trap)
{
union sbi_unpriv_data data;
trap->cause = 0;
while (len) {
unsigned int width = __riscv_xlen / 8;
void *ptr = (void*)addr;
while (len < width || (addr & (width - 1)))
width /= 2;
sbi_memcpy(data.bytes, buffer, width);
switch (width) {
case 1:
sbi_store_u8(ptr, data.b, trap);
break;
case 2:
sbi_store_u16(ptr, data.h, trap);
break;
case 4:
sbi_store_u32(ptr, data.w, trap);
break;
#if __riscv_xlen == 64
case 8:
sbi_store_u64(ptr, data.d, trap);
break;
#endif
}
if (trap->cause)
return;
len -= width;
addr += width;
buffer += width;
}
}
ulong sbi_get_insn(ulong mepc, struct sbi_trap_info *trap)
{
register ulong tinfo asm("a3");