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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id m4sm1326977wrx.81.2021.09.21.23.26.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Sep 2021 23:26:34 -0700 (PDT) Subject: Re: [PATCH v3 05/16] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv To: Sean Christopherson , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Marc Zyngier , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Boris Ostrovsky , Juergen Gross Cc: Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Zhu Lingshan References: <20210922000533.713300-1-seanjc@google.com> <20210922000533.713300-6-seanjc@google.com> From: Paolo Bonzini Message-ID: <2462bc44-64a5-8bac-7c3c-d837c4b3f743@redhat.com> Date: Wed, 22 Sep 2021 08:26:29 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210922000533.713300-6-seanjc@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 22/09/21 02:05, Sean Christopherson wrote: > Drop "support" for guest callbacks from architctures that don't implement > the guest callbacks. Future patches will convert the callbacks to > static_call; rather than churn a bunch of arch code (that was presumably > copy+pasted from x86), remove it wholesale as it's useless and at best > wasting cycles. > > A future patch will also add a Kconfig to force architcture to opt into > the callbacks to make it more difficult for uses "support" to sneak in in > the future. > > No functional change intended. > > Signed-off-by: Sean Christopherson > --- > arch/arm/kernel/perf_callchain.c | 33 ++++------------------------- > arch/csky/kernel/perf_callchain.c | 12 ----------- > arch/nds32/kernel/perf_event_cpu.c | 34 ++++-------------------------- > arch/riscv/kernel/perf_callchain.c | 13 ------------ > 4 files changed, 8 insertions(+), 84 deletions(-) > > diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c > index 1626dfc6f6ce..bc6b246ab55e 100644 > --- a/arch/arm/kernel/perf_callchain.c > +++ b/arch/arm/kernel/perf_callchain.c > @@ -62,14 +62,8 @@ user_backtrace(struct frame_tail __user *tail, > void > perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > struct frame_tail __user *tail; > > - if (guest_cbs && guest_cbs->is_in_guest()) { > - /* We don't support guest os callchain now */ > - return; > - } > - > perf_callchain_store(entry, regs->ARM_pc); > > if (!current->mm) > @@ -99,44 +93,25 @@ callchain_trace(struct stackframe *fr, > void > perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > struct stackframe fr; > > - if (guest_cbs && guest_cbs->is_in_guest()) { > - /* We don't support guest os callchain now */ > - return; > - } > - > arm_get_current_stackframe(regs, &fr); > walk_stackframe(&fr, callchain_trace, entry); > } > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > - > - if (guest_cbs && guest_cbs->is_in_guest()) > - return guest_cbs->get_guest_ip(); > - > return instruction_pointer(regs); > } > > unsigned long perf_misc_flags(struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > int misc = 0; > > - if (guest_cbs && guest_cbs->is_in_guest()) { > - if (guest_cbs->is_user_mode()) > - misc |= PERF_RECORD_MISC_GUEST_USER; > - else > - misc |= PERF_RECORD_MISC_GUEST_KERNEL; > - } else { > - if (user_mode(regs)) > - misc |= PERF_RECORD_MISC_USER; > - else > - misc |= PERF_RECORD_MISC_KERNEL; > - } > + if (user_mode(regs)) > + misc |= PERF_RECORD_MISC_USER; > + else > + misc |= PERF_RECORD_MISC_KERNEL; > > return misc; > } > diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c > index 35318a635a5f..92057de08f4f 100644 > --- a/arch/csky/kernel/perf_callchain.c > +++ b/arch/csky/kernel/perf_callchain.c > @@ -86,13 +86,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, > void perf_callchain_user(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > unsigned long fp = 0; > > - /* C-SKY does not support virtualization. */ > - if (guest_cbs && guest_cbs->is_in_guest()) > - return; > - > fp = regs->regs[4]; > perf_callchain_store(entry, regs->pc); > > @@ -111,15 +106,8 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, > void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > struct stackframe fr; > > - /* C-SKY does not support virtualization. */ > - if (guest_cbs && guest_cbs->is_in_guest()) { > - pr_warn("C-SKY does not support perf in guest mode!"); > - return; > - } > - > fr.fp = regs->regs[4]; > fr.lr = regs->lr; > walk_stackframe(&fr, entry); > diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c > index f38791960781..a78a879e7ef1 100644 > --- a/arch/nds32/kernel/perf_event_cpu.c > +++ b/arch/nds32/kernel/perf_event_cpu.c > @@ -1363,7 +1363,6 @@ void > perf_callchain_user(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > unsigned long fp = 0; > unsigned long gp = 0; > unsigned long lp = 0; > @@ -1372,11 +1371,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, > > leaf_fp = 0; > > - if (guest_cbs && guest_cbs->is_in_guest()) { > - /* We don't support guest os callchain now */ > - return; > - } > - > perf_callchain_store(entry, regs->ipc); > fp = regs->fp; > gp = regs->gp; > @@ -1480,13 +1474,8 @@ void > perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > struct stackframe fr; > > - if (guest_cbs && guest_cbs->is_in_guest()) { > - /* We don't support guest os callchain now */ > - return; > - } > fr.fp = regs->fp; > fr.lp = regs->lp; > fr.sp = regs->sp; > @@ -1495,32 +1484,17 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > - > - /* However, NDS32 does not support virtualization */ > - if (guest_cbs && guest_cbs->is_in_guest()) > - return guest_cbs->get_guest_ip(); > - > return instruction_pointer(regs); > } > > unsigned long perf_misc_flags(struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > int misc = 0; > > - /* However, NDS32 does not support virtualization */ > - if (guest_cbs && guest_cbs->is_in_guest()) { > - if (guest_cbs->is_user_mode()) > - misc |= PERF_RECORD_MISC_GUEST_USER; > - else > - misc |= PERF_RECORD_MISC_GUEST_KERNEL; > - } else { > - if (user_mode(regs)) > - misc |= PERF_RECORD_MISC_USER; > - else > - misc |= PERF_RECORD_MISC_KERNEL; > - } > + if (user_mode(regs)) > + misc |= PERF_RECORD_MISC_USER; > + else > + misc |= PERF_RECORD_MISC_KERNEL; > > return misc; > } > diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c > index 8ecfc4c128bc..1fc075b8f764 100644 > --- a/arch/riscv/kernel/perf_callchain.c > +++ b/arch/riscv/kernel/perf_callchain.c > @@ -56,13 +56,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, > void perf_callchain_user(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > unsigned long fp = 0; > > - /* RISC-V does not support perf in guest mode. */ > - if (guest_cbs && guest_cbs->is_in_guest()) > - return; > - > fp = regs->s0; > perf_callchain_store(entry, regs->epc); > > @@ -79,13 +74,5 @@ static bool fill_callchain(void *entry, unsigned long pc) > void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, > struct pt_regs *regs) > { > - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); > - > - /* RISC-V does not support perf in guest mode. */ > - if (guest_cbs && guest_cbs->is_in_guest()) { > - pr_warn("RISC-V does not support perf in guest mode!"); > - return; > - } > - > walk_stackframe(NULL, regs, fill_callchain, entry); > } > Reviewed-by: Paolo Bonzini