[PATCH]: d03d02e683 target/riscv: vstart should be preserved when manipulating vector state

[<ge...@op...>]

This is an automated email from Gerrit.

"Anatoly P <kup...@gm...>" just uploaded a new patch set to Gerrit, which you can find at https://review.openocd.org/c/openocd/+/9415

-- gerrit

commit d03d02e68345716861b6901ec5491afcc2ee8b30
Author: Anatoly Parshintsev <ana...@sy...>
Date:   Tue Jan 27 00:19:55 2026 +0300

    target/riscv: vstart should be preserved when manipulating vector state
    
    read access should not ruin the current execution context
    
    Change-Id: I76a932986958c5715a7b5dd0012c868303a6c83b
    Signed-off-by: Anatoly Parshintsev <ana...@sy...>

diff --git a/src/target/riscv/riscv-013.c b/src/target/riscv/riscv-013.c
index 50e0f83dd8..c3565e23a7 100644
--- a/src/target/riscv/riscv-013.c
+++ b/src/target/riscv/riscv-013.c
@@ -2318,7 +2318,7 @@ static int try_set_vsew(struct target *target, unsigned int *debug_vsew)
 
 static int prep_for_vector_access(struct target *target,
 		riscv_reg_t *orig_mstatus, riscv_reg_t *orig_vtype, riscv_reg_t *orig_vl,
-		unsigned int *debug_vl, unsigned int *debug_vsew)
+		riscv_reg_t *orig_vstart, unsigned int *debug_vl, unsigned int *debug_vsew)
 {
 	assert(orig_mstatus);
 	assert(orig_vtype);
@@ -2335,12 +2335,15 @@ static int prep_for_vector_access(struct target *target,
 	if (prep_for_register_access(target, orig_mstatus, GDB_REGNO_VL) != ERROR_OK)
 		return ERROR_FAIL;
 
-	/* Save vtype and vl. */
+	/* Save original vstart, vtype and vl values for later restoration */
+	if (riscv_reg_get(target, orig_vstart, GDB_REGNO_VSTART) != ERROR_OK)
+		return ERROR_FAIL;
 	if (riscv_reg_get(target, orig_vtype, GDB_REGNO_VTYPE) != ERROR_OK)
 		return ERROR_FAIL;
 	if (riscv_reg_get(target, orig_vl, GDB_REGNO_VL) != ERROR_OK)
 		return ERROR_FAIL;
-
+	/* Note: vstart may be non-zero at this point. Updating vsew (via VTYPE)
+	 * reset vstart to 0. */
 	if (try_set_vsew(target, debug_vsew) != ERROR_OK)
 		return ERROR_FAIL;
 	/* Set the number of elements to be updated with results from a vector
@@ -2351,13 +2354,15 @@ static int prep_for_vector_access(struct target *target,
 }
 
 static int cleanup_after_vector_access(struct target *target,
-		riscv_reg_t mstatus, riscv_reg_t vtype, riscv_reg_t vl)
+		riscv_reg_t mstatus, riscv_reg_t vtype, riscv_reg_t vl, riscv_reg_t vstart)
 {
-	/* Restore vtype and vl. */
+	/* Restore vtype, vl and vstart. */
 	if (riscv_reg_write(target, GDB_REGNO_VTYPE, vtype) != ERROR_OK)
 		return ERROR_FAIL;
 	if (riscv_reg_write(target, GDB_REGNO_VL, vl) != ERROR_OK)
 		return ERROR_FAIL;
+	if (riscv_reg_write(target, GDB_REGNO_VSTART, vstart) != ERROR_OK)
+		return ERROR_FAIL;
 	return cleanup_after_register_access(target, mstatus, GDB_REGNO_VL);
 }
 
@@ -2369,10 +2374,10 @@ int riscv013_get_register_buf(struct target *target, uint8_t *value,
 	if (dm013_select_target(target) != ERROR_OK)
 		return ERROR_FAIL;
 
-	riscv_reg_t mstatus, vtype, vl;
+	riscv_reg_t mstatus, vtype, vl, vstart;
 	unsigned int debug_vl, debug_vsew;
 
-	if (prep_for_vector_access(target, &mstatus, &vtype, &vl,
+	if (prep_for_vector_access(target, &mstatus, &vtype, &vl, &vstart,
 				&debug_vl, &debug_vsew) != ERROR_OK)
 		return ERROR_FAIL;
 
@@ -2410,7 +2415,7 @@ int riscv013_get_register_buf(struct target *target, uint8_t *value,
 		}
 	}
 
-	if (cleanup_after_vector_access(target, mstatus, vtype, vl) != ERROR_OK)
+	if (cleanup_after_vector_access(target, mstatus, vtype, vl, vstart) != ERROR_OK)
 		return ERROR_FAIL;
 
 	return result;
@@ -2424,10 +2429,10 @@ int riscv013_set_register_buf(struct target *target, enum gdb_regno regno,
 	if (dm013_select_target(target) != ERROR_OK)
 		return ERROR_FAIL;
 
-	riscv_reg_t mstatus, vtype, vl;
+	riscv_reg_t mstatus, vtype, vl, vstart;
 	unsigned int debug_vl, debug_vsew;
 
-	if (prep_for_vector_access(target, &mstatus, &vtype, &vl,
+	if (prep_for_vector_access(target, &mstatus, &vtype, &vl, &vstart,
 				&debug_vl, &debug_vsew) != ERROR_OK)
 		return ERROR_FAIL;
 
@@ -2449,7 +2454,7 @@ int riscv013_set_register_buf(struct target *target, enum gdb_regno regno,
 			break;
 	}
 
-	if (cleanup_after_vector_access(target, mstatus, vtype, vl) != ERROR_OK)
+	if (cleanup_after_vector_access(target, mstatus, vtype, vl, vstart) != ERROR_OK)
 		return ERROR_FAIL;
 
 	return result;

--