[PATCH 3/4] lib: sbi_scratch: Add sbi_hart_count() and for_each_hartindex()

[Samuel Holland]

There is currently no helper for iterating through the harts in a
system, and code must choose between sbi_scratch_last_hartindex() and
sbi_platform_hart_count() for the loop condition.

sbi_scratch_last_hartindex() has unusual semantics, leading to the
likelihood of off-by-one errors, and sbi_platform_hart_count() is
provided by the platform and so may not be properly bounded.

Add a new helper which definitively reports the number of harts managed
by this OpenSBI instance, i.e. the number of valid hart indexes, and a
convenient iterator macro.

Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
---

 include/sbi/sbi_scratch.h | 16 +++++++++++-----
 lib/sbi/sbi_scratch.c     | 13 +++++--------
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/sbi/sbi_scratch.h b/include/sbi/sbi_scratch.h
index 1ec1710e..200f73d2 100644
--- a/include/sbi/sbi_scratch.h
+++ b/include/sbi/sbi_scratch.h
@@ -210,15 +210,21 @@ do {									\
 #define current_hartindex() \
 	(sbi_scratch_thishart_ptr()->hartindex)
 
-/** Last HART index having a sbi_scratch pointer */
-extern u32 last_hartindex_having_scratch;
+/** Number of harts managed by this OpenSBI instance */
+extern u32 sbi_scratch_hart_count;
+
+/** Get the number of harts managed by this OpenSBI instance */
+#define sbi_hart_count() sbi_scratch_hart_count
+
+/** Iterate over the harts managed by this OpenSBI instance */
+#define for_each_hartindex(__var) \
+	for (u32 __var = 0; __var < sbi_hart_count(); ++__var)
 
 /** Get last HART index having a sbi_scratch pointer */
-#define sbi_scratch_last_hartindex()	last_hartindex_having_scratch
+#define sbi_scratch_last_hartindex() (sbi_hart_count() - 1)
 
 /** Check whether a particular HART index is valid or not */
-#define sbi_hartindex_valid(__hartindex) \
-(((__hartindex) <= sbi_scratch_last_hartindex()) ? true : false)
+#define sbi_hartindex_valid(__hartindex) ((__hartindex) < sbi_hart_count())
 
 /** HART index to HART id table */
 extern u32 hartindex_to_hartid_table[];
diff --git a/lib/sbi/sbi_scratch.c b/lib/sbi/sbi_scratch.c
index e1cc5658..2dc028ee 100644
--- a/lib/sbi/sbi_scratch.c
+++ b/lib/sbi/sbi_scratch.c
@@ -14,7 +14,7 @@
 #include <sbi/sbi_scratch.h>
 #include <sbi/sbi_string.h>
 
-u32 last_hartindex_having_scratch = 0;
+u32 sbi_scratch_hart_count;
 u32 hartindex_to_hartid_table[SBI_HARTMASK_MAX_BITS] = { [0 ... SBI_HARTMASK_MAX_BITS-1] = -1U };
 struct sbi_scratch *hartindex_to_scratch_table[SBI_HARTMASK_MAX_BITS];
 
@@ -23,9 +23,7 @@ static unsigned long extra_offset = SBI_SCRATCH_EXTRA_SPACE_OFFSET;
 
 u32 sbi_hartid_to_hartindex(u32 hartid)
 {
-	u32 i;
-
-	for (i = 0; i <= last_hartindex_having_scratch; i++)
+	for_each_hartindex(i)
 		if (hartindex_to_hartid_table[i] == hartid)
 			return i;
 
@@ -36,22 +34,21 @@ typedef struct sbi_scratch *(*hartid2scratch)(ulong hartid, ulong hartindex);
 
 int sbi_scratch_init(struct sbi_scratch *scratch)
 {
-	u32 i, h, hart_count;
+	u32 h, hart_count;
 	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
 	hart_count = plat->hart_count;
 	if (hart_count > SBI_HARTMASK_MAX_BITS)
 		hart_count = SBI_HARTMASK_MAX_BITS;
+	sbi_scratch_hart_count = hart_count;
 
-	for (i = 0; i < hart_count; i++) {
+	for_each_hartindex(i) {
 		h = (plat->hart_index2id) ? plat->hart_index2id[i] : i;
 		hartindex_to_hartid_table[i] = h;
 		hartindex_to_scratch_table[i] =
 			((hartid2scratch)scratch->hartid_to_scratch)(h, i);
 	}
 
-	last_hartindex_having_scratch = hart_count - 1;
-
 	return 0;
 }
 
-- 
2.47.2