[PATCH 2/3] lib: sbi: Add pmp_set_tor for setting TOR regions

Bo Gan
2025-11-11T03:42:56Z

TOR can be utilized to cover memory regions that are not aligned with
their sizes. Given that the address matching is formed bt 2 consecutive
pmpaddr, i.e., pmpaddr(i-1) and pmpaddr(i), TOR should not be used
generically to avoid pmpaddr conflict with other NA4/NAPOT regions.

It's advised to only use them in platform code where the caller can
ensure the index and order of every pmp region especially when there's
a mixture of TOR/NA4/NAPOT.

Signed-off-by: Bo Gan <ganboing@gmail.com>
---
include/sbi/riscv_asm.h | 4 +++
lib/sbi/riscv_asm.c | 75 +++++++++++++++++++++++++++++++----------
2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h
index ef48dc89..c23feab6 100644
--- a/include/sbi/riscv_asm.h
+++ b/include/sbi/riscv_asm.h
@@ -218,6 +218,10 @@ int is_pmp_entry_mapped(unsigned long entry);
int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
unsigned long log2len);

+/* Top of range (TOR) matching mode. pmpaddr(n-1) will also be changed */
+int pmp_set_tor(unsigned int n, unsigned long prot, unsigned long addr,
+ unsigned long size);
+
int pmp_get(unsigned int n, unsigned long *prot_out, unsigned long *addr_out,
unsigned long *log2len);

diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
index 3e44320f..8f64f2b5 100644
--- a/lib/sbi/riscv_asm.c
+++ b/lib/sbi/riscv_asm.c
@@ -330,16 +330,10 @@ int is_pmp_entry_mapped(unsigned long entry)
return false;
}

-int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
- unsigned long log2len)
+static void pmp_set_prot(unsigned int n, unsigned long prot)
{
- int pmpcfg_csr, pmpcfg_shift, pmpaddr_csr;
+ int pmpcfg_csr, pmpcfg_shift;
unsigned long cfgmask, pmpcfg;
- unsigned long addrmask, pmpaddr;
-
- /* check parameters */
- if (n >= PMP_COUNT || log2len > __riscv_xlen || log2len < PMP_SHIFT)
- return SBI_EINVAL;

/* calculate PMP register and offset */
#if __riscv_xlen == 32
@@ -351,15 +345,29 @@ int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
#else
# error "Unexpected __riscv_xlen"
#endif
- pmpaddr_csr = CSR_PMPADDR0 + n;
-
- /* encode PMP config */
- prot &= ~PMP_A;
- prot |= (log2len == PMP_SHIFT) ? PMP_A_NA4 : PMP_A_NAPOT;
cfgmask = ~(0xffUL << pmpcfg_shift);
pmpcfg = (csr_read_num(pmpcfg_csr) & cfgmask);
pmpcfg |= ((prot << pmpcfg_shift) & ~cfgmask);

+ csr_write_num(pmpcfg_csr, pmpcfg);
+}
+
+static void pmp_set_addr(unsigned int n, unsigned long pmpaddr)
+{
+ int pmpaddr_csr = CSR_PMPADDR0 + n;
+
+ csr_write_num(pmpaddr_csr, pmpaddr);
+}
+
+int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
+ unsigned long log2len)
+{
+ unsigned long addrmask, pmpaddr;
+
+ /* check parameters */
+ if (n >= PMP_COUNT || log2len > __riscv_xlen || log2len < PMP_SHIFT)
+ return SBI_EINVAL;
+
/* encode PMP address */
if (log2len == PMP_SHIFT) {
pmpaddr = (addr >> PMP_SHIFT);
@@ -373,10 +381,41 @@ int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
}
}

+ /* encode PMP config */
+ prot &= ~PMP_A;
+ prot |= (log2len == PMP_SHIFT) ? PMP_A_NA4 : PMP_A_NAPOT;
+
/* write csrs */
- csr_write_num(pmpaddr_csr, pmpaddr);
- csr_write_num(pmpcfg_csr, pmpcfg);
+ pmp_set_addr(n, pmpaddr);
+ pmp_set_prot(n, prot);
+ return 0;
+}
+
+int pmp_set_tor(unsigned int n, unsigned long prot, unsigned long addr,
+ unsigned long size)
+{
+ unsigned long pmpaddr, pmpaddrp;
+
+ /* check parameters */
+ if (n >= PMP_COUNT)
+ return SBI_EINVAL;
+
+ if (n == 0 && addr != 0)
+ return SBI_EINVAL;
+
+ /* encode PMP address */
+ pmpaddrp = addr >> PMP_SHIFT;
+ pmpaddr = (addr + size) >> PMP_SHIFT;

+ /* encode PMP config */
+ prot &= ~PMP_A;
+ prot |= PMP_A_TOR;
+
+ /* write csrs */
+ if (n)
+ pmp_set_addr(n - 1, pmpaddrp);
+ pmp_set_addr(n, pmpaddr);
+ pmp_set_prot(n, prot);
return 0;
}

@@ -420,10 +459,12 @@ int pmp_get(unsigned int n, unsigned long *prot_out, unsigned long *addr_out,
addr = (addr & ~((1UL << t1) - 1)) << PMP_SHIFT;
len = (t1 + PMP_SHIFT + 1);
}
- } else {
+ } else if ((prot & PMP_A) == PMP_A_NA4) {
addr = csr_read_num(pmpaddr_csr) << PMP_SHIFT;
len = PMP_SHIFT;
- }
+ } else
+ /* Error out for TOR region */
+ return SBI_EINVAL;

/* return details */
*prot_out = prot;
--
2.34.1