The branch main has been updated by andrew:
URL:
https://cgit.FreeBSD.org/src/commit/?id=f820b6ed34d5e97835d7f55d63076f07ed5d7ef5
commit f820b6ed34d5e97835d7f55d63076f07ed5d7ef5
Author: Andrew Turner <and...@freebsd.org>
AuthorDate: 2025-06-23 10:15:00 +0000
Commit: Andrew Turner <and...@freebsd.org>
CommitDate: 2025-06-23 10:18:19 +0000
arm64: Switch to get_user_reg in fill_dbregs
This lets us read the register in one go then decode it, rather than
searching for the register 3 times.
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D50903
---
sys/arm64/arm64/exec_machdep.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/sys/arm64/arm64/exec_machdep.c b/sys/arm64/arm64/exec_machdep.c
index 6a536233a62d..751329affd91 100644
--- a/sys/arm64/arm64/exec_machdep.c
+++ b/sys/arm64/arm64/exec_machdep.c
@@ -191,17 +191,27 @@ int
fill_dbregs(struct thread *td, struct dbreg *regs)
{
struct debug_monitor_state *monitor;
+ uint64_t dfr0;
int i;
uint8_t debug_ver, nbkpts, nwtpts;
memset(regs, 0, sizeof(*regs));
- extract_user_id_field(ID_AA64DFR0_EL1, ID_AA64DFR0_DebugVer_SHIFT,
- &debug_ver);
- extract_user_id_field(ID_AA64DFR0_EL1, ID_AA64DFR0_BRPs_SHIFT,
- &nbkpts);
- extract_user_id_field(ID_AA64DFR0_EL1, ID_AA64DFR0_WRPs_SHIFT,
- &nwtpts);
+ /*
+ * Read these the Debug Feature Register 0 to get info we need.
+ * It will be identical on FreeBSD and Linux, so there is no need
+ * to check which the target is.
+ */
+ if (!get_user_reg(ID_AA64DFR0_EL1, &dfr0, true)) {
+ debug_ver = ID_AA64DFR0_DebugVer_8;
+ nbkpts = 0;
+ nwtpts = 0;
+ } else {
+ debug_ver = ID_AA64DFR0_DebugVer_VAL(dfr0) >>
+ ID_AA64DFR0_DebugVer_SHIFT;
+ nbkpts = ID_AA64DFR0_BRPs_VAL(dfr0) >> ID_AA64DFR0_BRPs_SHIFT;
+ nwtpts = ID_AA64DFR0_WRPs_VAL(dfr0) >> ID_AA64DFR0_WRPs_SHIFT;
+ }
/*
* The BRPs field contains the number of breakpoints - 1. Armv8-A
