Date: Tue, 10 Sep 2024 19:04:59 +0100 From: Jessica Clarke <jrtc27@freebsd.org> To: Andrew Turner <andrew@FreeBSD.org> Cc: "src-committers@freebsd.org" <src-committers@FreeBSD.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@FreeBSD.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org> Subject: Re: git: f05795e3f65f - main - arm64: write PID in CONTEXTIDR_EL1 on ctx switch Message-ID: <E4ED5EC8-92CD-4CE6-A1E6-0313CF87B630@freebsd.org> In-Reply-To: <202409091605.489G5X6W041843@gitrepo.freebsd.org> References: <202409091605.489G5X6W041843@gitrepo.freebsd.org>
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On 9 Sep 2024, at 17:05, Andrew Turner <andrew@FreeBSD.org> wrote: >=20 > The branch main has been updated by andrew: >=20 > URL: = https://cgit.FreeBSD.org/src/commit/?id=3Df05795e3f65f305cb770ae91d8e9c8f0= 5d267e0d >=20 > commit f05795e3f65f305cb770ae91d8e9c8f05d267e0d > Author: Zachary Leaf <zachary.leaf@arm.com> > AuthorDate: 2024-07-31 08:23:24 +0000 > Commit: Andrew Turner <andrew@FreeBSD.org> > CommitDate: 2024-09-09 16:03:19 +0000 >=20 > arm64: write PID in CONTEXTIDR_EL1 on ctx switch >=20 > Debug and trace features such as Statistical Profiling Extension = (SPE) > use the CONTEXTIDR_EL1 register to get the PID of the current = process. >=20 > Add a sysctl switch to toggle writing the current PID into this = register > in the thread switcher. >=20 > To make use of the feature, the following sysctl switch must be = set: >=20 > sysctl machdep.pid_in_contextidr=3D1 >=20 > Kernel code can also toggle the sysctl by writing directly to the = global > var behind the sysctl arm64_pid_in_contextidr: >=20 > extern bool arm64_pid_in_contextidr; >=20 > Reviewed by: andrew > Sponsored by: Arm Ltd > Differential Revision: https://reviews.freebsd.org/D46192 > --- > sys/arm64/arm64/genassym.c | 2 ++ > sys/arm64/arm64/swtch.S | 17 +++++++++++++++++ > sys/arm64/arm64/sys_machdep.c | 6 ++++++ > 3 files changed, 25 insertions(+) >=20 > 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)); >=20 > +ASSYM(PR_PID, offsetof(struct proc, p_pid)); > + > ASSYM(SF_UC, offsetof(struct sigframe, sf_uc)); >=20 > 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 >=20 > +.macro pid_in_context_idr label > + adrp x9, arm64_pid_in_contextidr > + ldr x10, [x9, :lo12:arm64_pid_in_contextidr] This loads a 64-bit value, not an 8-bit bool as the variable is defined. Depending on the alignment of arm64_pid_in_contextidr this can even fail to link, and this shows up in GitHub Actions with the clang-12 and clang-13 jobs failing. Jess
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