diff options
| author | Zachary Leaf <zachary.leaf@arm.com> | 2024-07-31 08:23:24 +0000 |
|---|---|---|
| committer | Andrew Turner <andrew@FreeBSD.org> | 2024-09-09 16:03:19 +0000 |
| commit | f05795e3f65f305cb770ae91d8e9c8f05d267e0d (patch) | |
| tree | 3ecc564038e265842f9846fcbeef8ed0ecccead2 | |
| parent | 610348a90467980de0498fab8dfdddf221d7a604 (diff) | |
arm64: write PID in CONTEXTIDR_EL1 on ctx switch
Debug and trace features such as Statistical Profiling Extension (SPE)
use the CONTEXTIDR_EL1 register to get the PID of the current process.
Add a sysctl switch to toggle writing the current PID into this register
in the thread switcher.
To make use of the feature, the following sysctl switch must be set:
sysctl machdep.pid_in_contextidr=1
Kernel code can also toggle the sysctl by writing directly to the global
var behind the sysctl arm64_pid_in_contextidr:
extern bool arm64_pid_in_contextidr;
Reviewed by: andrew
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D46192
| -rw-r--r-- | sys/arm64/arm64/genassym.c | 2 | ||||
| -rw-r--r-- | sys/arm64/arm64/swtch.S | 17 | ||||
| -rw-r--r-- | sys/arm64/arm64/sys_machdep.c | 6 |
3 files changed, 25 insertions, 0 deletions
diff --git a/sys/arm64/arm64/genassym.c b/sys/arm64/arm64/genassym.c index a4db825e976c..5a20169d51c3 100644 --- a/sys/arm64/arm64/genassym.c +++ b/sys/arm64/arm64/genassym.c @@ -58,6 +58,8 @@ ASSYM(PCB_TPIDRRO, offsetof(struct pcb, pcb_tpidrro_el0)); ASSYM(PCB_ONFAULT, offsetof(struct pcb, pcb_onfault)); ASSYM(PCB_FLAGS, offsetof(struct pcb, pcb_flags)); +ASSYM(PR_PID, offsetof(struct proc, p_pid)); + ASSYM(SF_UC, offsetof(struct sigframe, sf_uc)); ASSYM(TD_PROC, offsetof(struct thread, td_proc)); diff --git a/sys/arm64/arm64/swtch.S b/sys/arm64/arm64/swtch.S index 6af70ca839a0..3a2bf2cb5a7f 100644 --- a/sys/arm64/arm64/swtch.S +++ b/sys/arm64/arm64/swtch.S @@ -55,6 +55,15 @@ 999: .endm +.macro pid_in_context_idr label + adrp x9, arm64_pid_in_contextidr + ldr x10, [x9, :lo12:arm64_pid_in_contextidr] + cbz x10, \label + ldr x9, [x1, #TD_PROC] + ldr x10, [x9, #PR_PID] + msr contextidr_el1, x10 +.endm + /* * void cpu_throw(struct thread *old, struct thread *new) */ @@ -66,8 +75,12 @@ ENTRY(cpu_throw) ldr x4, [x0, #TD_PCB] ldr w5, [x4, #PCB_FLAGS] clear_step_flag w5, x6 + 1: + /* debug/trace: set CONTEXTIDR_EL1 to current PID, if enabled */ + pid_in_context_idr 2f +2: #ifdef VFP /* Backup the new thread pointer around a call to C code */ mov x19, x1 @@ -147,6 +160,10 @@ ENTRY(cpu_switch) mov x20, x1 mov x21, x2 + /* debug/trace: set CONTEXTIDR_EL1 to current PID, if enabled */ + pid_in_context_idr 0f + +0: #ifdef VFP bl vfp_save_state_switch mov x0, x20 diff --git a/sys/arm64/arm64/sys_machdep.c b/sys/arm64/arm64/sys_machdep.c index eedc57f7c572..eedee1d27015 100644 --- a/sys/arm64/arm64/sys_machdep.c +++ b/sys/arm64/arm64/sys_machdep.c @@ -30,6 +30,7 @@ #include <sys/param.h> #include <sys/systm.h> #include <sys/proc.h> +#include <sys/sysctl.h> #include <sys/sysproto.h> #include <vm/vm.h> @@ -80,3 +81,8 @@ sysarch(struct thread *td, struct sysarch_args *uap) return (error); } + +bool arm64_pid_in_contextidr = false; +SYSCTL_BOOL(_machdep, OID_AUTO, pid_in_contextidr, CTLFLAG_RW, + &arm64_pid_in_contextidr, false, + "Save PID into CONTEXTIDR_EL1 register on context switch"); |