From: Bo Gan <ganboing@gmail.com>
To: opensbi@lists.infradead.org
Cc: linmin@eswincomputing.com, pinkesh.vaghela@einfochips.com,
gaohan@iscas.ac.cn, samuel@sholland.org, wangxiang@iscas.ac.cn
Subject: [PATCH v4 4/5] lib: sbi: give platform choice of using single memregion to cover OpenSBI
Date: Tue, 9 Dec 2025 02:22:45 -0800 [thread overview]
Message-ID: <20251209102246.1161-5-ganboing@gmail.com> (raw)
In-Reply-To: <20251209102246.1161-1-ganboing@gmail.com>
By default the OpenSBI itself is covered by 2 memregions for RX/RW
sections. This is required by platforms with Smepmp to enforce
proper permissions in M mode. Note: M-mode only regions can't
have RWX permissions with Smepmp. Platforms with traditional PMPs
won't be able to benefit from it, as both regions are effectively
RWX in M mode, but usually it's harmless to so. Now we provide
these platforms with an option to disable this logic. It saves 1
PMP entry. For platforms really in short of PMPs, it does make a
difference.
Note: Platform requesting single OpenSBI memregion must be using
traditional (old) PMP. We expect the platform code to do
the right thing.
Signed-off-by: Bo Gan <ganboing@gmail.com>
---
include/sbi/sbi_platform.h | 21 +++++++++++++++++++++
lib/sbi/sbi_domain.c | 36 ++++++++++++++++++++++++------------
2 files changed, 45 insertions(+), 12 deletions(-)
diff --git a/include/sbi/sbi_platform.h b/include/sbi/sbi_platform.h
index d75c12de..e65d9877 100644
--- a/include/sbi/sbi_platform.h
+++ b/include/sbi/sbi_platform.h
@@ -76,6 +76,9 @@ struct sbi_platform_operations {
/* Check if specified HART is allowed to do cold boot */
bool (*cold_boot_allowed)(u32 hartid);
+ /* Check if platform requires single firmware region */
+ bool (*single_fw_region)(void);
+
/* Platform nascent initialization */
int (*nascent_init)(void);
@@ -347,6 +350,24 @@ static inline bool sbi_platform_cold_boot_allowed(
return true;
}
+/**
+ * Check whether platform requires single firmware region
+ *
+ * Note: Single firmware region only works with legacy PMP because with
+ * Smepmp M-mode only regions can't have RWX permissions.
+ *
+ * @param plat pointer to struct sbi_platform
+ *
+ * @return true if single firmware region required and false otherwise
+ */
+static inline bool sbi_platform_single_fw_region(
+ const struct sbi_platform *plat)
+{
+ if (plat && sbi_platform_ops(plat)->single_fw_region)
+ return sbi_platform_ops(plat)->single_fw_region();
+ return false;
+}
+
/**
* Nascent (very early) initialization for current HART
*
diff --git a/lib/sbi/sbi_domain.c b/lib/sbi/sbi_domain.c
index 8a0a8fe2..4d3b4ee4 100644
--- a/lib/sbi/sbi_domain.c
+++ b/lib/sbi/sbi_domain.c
@@ -919,18 +919,30 @@ int sbi_domain_init(struct sbi_scratch *scratch, u32 cold_hartid)
root.possible_harts = root_hmask;
/* Root domain firmware memory region */
- sbi_domain_memregion_init(scratch->fw_start, scratch->fw_rw_offset,
- (SBI_DOMAIN_MEMREGION_M_READABLE |
- SBI_DOMAIN_MEMREGION_M_EXECUTABLE |
- SBI_DOMAIN_MEMREGION_FW),
- &root_memregs[root_memregs_count++]);
-
- sbi_domain_memregion_init((scratch->fw_start + scratch->fw_rw_offset),
- (scratch->fw_size - scratch->fw_rw_offset),
- (SBI_DOMAIN_MEMREGION_M_READABLE |
- SBI_DOMAIN_MEMREGION_M_WRITABLE |
- SBI_DOMAIN_MEMREGION_FW),
- &root_memregs[root_memregs_count++]);
+ if (sbi_platform_single_fw_region(sbi_platform_ptr(scratch))) {
+ sbi_domain_memregion_init(scratch->fw_start, scratch->fw_size,
+ (SBI_DOMAIN_MEMREGION_M_READABLE |
+ SBI_DOMAIN_MEMREGION_M_WRITABLE |
+ SBI_DOMAIN_MEMREGION_M_EXECUTABLE |
+ SBI_DOMAIN_MEMREGION_FW),
+ &root_memregs[root_memregs_count++]);
+ } else {
+ sbi_domain_memregion_init(scratch->fw_start,
+ scratch->fw_rw_offset,
+ (SBI_DOMAIN_MEMREGION_M_READABLE |
+ SBI_DOMAIN_MEMREGION_M_EXECUTABLE |
+ SBI_DOMAIN_MEMREGION_FW),
+ &root_memregs[root_memregs_count++]);
+
+ sbi_domain_memregion_init((scratch->fw_start +
+ scratch->fw_rw_offset),
+ (scratch->fw_size -
+ scratch->fw_rw_offset),
+ (SBI_DOMAIN_MEMREGION_M_READABLE |
+ SBI_DOMAIN_MEMREGION_M_WRITABLE |
+ SBI_DOMAIN_MEMREGION_FW),
+ &root_memregs[root_memregs_count++]);
+ }
root.fw_region_inited = true;
--
2.34.1
--
opensbi mailing list
opensbi@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/opensbi
next prev parent reply other threads:[~2025-12-09 10:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-09 10:22 [PATCH v4 0/5] Initial ESWIN/EIC7700 support Bo Gan
2025-12-09 10:22 ` [PATCH v4 1/5] lib: sbi_hart_pmp: make sbi_hart_pmp_fence public Bo Gan
2025-12-09 10:22 ` [PATCH v4 2/5] lib: sbi_domain: add sbi_domain_get_oldpmp_flags Bo Gan
2025-12-09 10:22 ` [PATCH v4 3/5] lib: sbi_domain: make is_region_subset public Bo Gan
2025-12-09 10:22 ` Bo Gan [this message]
2025-12-09 10:22 ` [PATCH v4 5/5] platform: generic: eswin: add EIC7700 Bo Gan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20251209102246.1161-5-ganboing@gmail.com \
--to=ganboing@gmail.com \
--cc=gaohan@iscas.ac.cn \
--cc=linmin@eswincomputing.com \
--cc=opensbi@lists.infradead.org \
--cc=pinkesh.vaghela@einfochips.com \
--cc=samuel@sholland.org \
--cc=wangxiang@iscas.ac.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox