[PATCH 1/3] lib: sbi: allow platform to override PMP configuration

Bo Gan
2025-11-11T03:42:55Z

Platform sometimes wants to override the entire PMP configuration phase,
not just performing additional work for each individual PMP entry. This
allows platforms to insert SoC/core specific PMP entries in a way that
works together with the existing ones set by lib/ code, not conflicting.
platform can also choose to merge or skip memory regions in a reasonable
way in case there's a shortage of PMP entries.

In addition, `sbi_hart_oldpmp_configure` is made public and a callback
function `skip` is added, so platform code can built on top of it to
simplify PMP configuration override.

Signed-off-by: Bo Gan <ganboing@gmail.com>
---
include/sbi/sbi_hart.h | 9 +++++++++
include/sbi/sbi_platform.h | 33 +++++++++++++++++++++++++++++++++
lib/sbi/sbi_hart.c | 27 +++++++++++++++++++--------
3 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index e66dd52f..e5a221bd 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -133,6 +133,7 @@ struct sbi_hart_features {
};

struct sbi_scratch;
+struct sbi_domain_memregion;

int sbi_hart_reinit(struct sbi_scratch *scratch);
int sbi_hart_init(struct sbi_scratch *scratch, bool cold_boot);
@@ -148,6 +149,14 @@ unsigned int sbi_hart_pmp_addrbits(struct sbi_scratch *scratch);
unsigned int sbi_hart_mhpm_bits(struct sbi_scratch *scratch);
bool sbi_hart_smepmp_is_fw_region(unsigned int pmp_idx);
int sbi_hart_pmp_configure(struct sbi_scratch *scratch);
+int sbi_hart_oldpmp_configure(struct sbi_scratch *scratch,
+ unsigned int pmp_start,
+ unsigned int pmp_count,
+ unsigned int pmp_log2gran,
+ unsigned long pmp_addr_max,
+ bool (*skip)(struct sbi_domain_memregion *reg,
+ void *data),
+ void *data);
int sbi_hart_map_saddr(unsigned long base, unsigned long size);
int sbi_hart_unmap_saddr(void);
int sbi_hart_priv_version(struct sbi_scratch *scratch);
diff --git a/include/sbi/sbi_platform.h b/include/sbi/sbi_platform.h
index d75c12de..c6fc137f 100644
--- a/include/sbi/sbi_platform.h
+++ b/include/sbi/sbi_platform.h
@@ -146,6 +146,11 @@ struct sbi_platform_operations {
unsigned long log2len);
/** platform specific pmp disable on current HART */
void (*pmp_disable)(unsigned int n);
+
+ /** platform pmp configure override on current HART */
+ int (*pmp_configure)(unsigned int pmp_count,
+ unsigned int pmp_log2gran,
+ unsigned long pmp_addr_max);
};

/** Platform default per-HART stack size for exception/interrupt handling */
@@ -666,6 +671,34 @@ static inline void sbi_platform_pmp_disable(const struct sbi_platform *plat,
sbi_platform_ops(plat)->pmp_disable(n);
}

+/**
+ * Check if platform wants to override PMP configuration
+ *
+ * @param plat pointer to struct sbi_platform
+ */
+static inline bool sbi_platform_pmp_override(const struct sbi_platform *plat)
+{
+ return plat && sbi_platform_ops(plat)->pmp_configure;
+}
+
+/**
+ * Platform PMP configuration override
+ *
+ * @param plat pointer to struct sbi_platform
+ * @param pmp_count number of PMP entries
+ * @param pmp_log2gran PMP granularity
+ * @param pmp_addr_max largest value pmpaddr(x) can hold
+ */
+static inline int sbi_platform_pmp_configure(const struct sbi_platform *plat,
+ unsigned int pmp_count,
+ unsigned int pmp_log2gran,
+ unsigned long pmp_addr_max)
+{
+ return sbi_platform_ops(plat)->pmp_configure(pmp_count,
+ pmp_log2gran,
+ pmp_addr_max);
+}
+
#endif

#endif
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index a91703b4..4425f36b 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -433,18 +433,24 @@ static int sbi_hart_smepmp_configure(struct sbi_scratch *scratch,
return 0;
}

-static int sbi_hart_oldpmp_configure(struct sbi_scratch *scratch,
- unsigned int pmp_count,
- unsigned int pmp_log2gran,
- unsigned long pmp_addr_max)
+int sbi_hart_oldpmp_configure(struct sbi_scratch *scratch,
+ unsigned int pmp_start,
+ unsigned int pmp_count,
+ unsigned int pmp_log2gran,
+ unsigned long pmp_addr_max,
+ bool (*skip)(struct sbi_domain_memregion *reg,
+ void *data),
+ void *data)
{
struct sbi_domain_memregion *reg;
struct sbi_domain *dom = sbi_domain_thishart_ptr();
- unsigned int pmp_idx = 0;
+ unsigned int pmp_idx = pmp_start;
unsigned int pmp_flags;
unsigned long pmp_addr;

sbi_domain_for_each_memregion(dom, reg) {
+ if (skip && skip(reg, data))
+ continue;
if (!is_valid_pmp_idx(pmp_count, pmp_idx))
return SBI_EFAIL;

@@ -534,6 +540,7 @@ int sbi_hart_pmp_configure(struct sbi_scratch *scratch)
unsigned int pmp_bits, pmp_log2gran;
unsigned int pmp_count = sbi_hart_pmp_count(scratch);
unsigned long pmp_addr_max;
+ const struct sbi_platform *plat = sbi_platform_ptr(scratch);

if (!pmp_count)
return 0;
@@ -542,12 +549,16 @@ int sbi_hart_pmp_configure(struct sbi_scratch *scratch)
pmp_bits = sbi_hart_pmp_addrbits(scratch) - 1;
pmp_addr_max = (1UL << pmp_bits) | ((1UL << pmp_bits) - 1);

- if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMEPMP))
+ if (sbi_platform_pmp_override(plat))
+ rc = sbi_platform_pmp_configure(plat, pmp_count,
+ pmp_log2gran, pmp_addr_max);
+ else if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMEPMP))
rc = sbi_hart_smepmp_configure(scratch, pmp_count,
pmp_log2gran, pmp_addr_max);
else
- rc = sbi_hart_oldpmp_configure(scratch, pmp_count,
- pmp_log2gran, pmp_addr_max);
+ rc = sbi_hart_oldpmp_configure(scratch, 0, pmp_count,
+ pmp_log2gran, pmp_addr_max,
+ NULL, NULL);

/*
* As per section 3.7.2 of privileged specification v1.12,
--
2.34.1