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Sun, 27 Apr 2025 10:56:55 -0400 X-MC-Unique: O4ZXsu8TO7GR1XelWUl6qg-1 X-Mimecast-MFC-AGG-ID: O4ZXsu8TO7GR1XelWUl6qg_1745765813 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8B5311955DDE; Sun, 27 Apr 2025 14:56:52 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.18]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id D563E1800368; Sun, 27 Apr 2025 14:56:45 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 27 Apr 2025 16:56:14 +0200 (CEST) Date: Sun, 27 Apr 2025 16:56:06 +0200 From: Oleg Nesterov To: Jiri Olsa Cc: Peter Zijlstra , Andrii Nakryiko , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , David Laight , Thomas =?iso-8859-1?Q?Wei=DFschuh?= , Ingo Molnar Subject: Re: [PATCH perf/core 08/22] uprobes/x86: Add mapping for optimized uprobe trampolines Message-ID: <20250427145606.GC9350@redhat.com> References: <20250421214423.393661-1-jolsa@kernel.org> <20250421214423.393661-9-jolsa@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250421214423.393661-9-jolsa@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On 04/21, Jiri Olsa wrote: > > +static unsigned long find_nearest_page(unsigned long vaddr) > +{ > + struct vm_area_struct *vma, *prev = NULL; > + unsigned long prev_vm_end = PAGE_SIZE; > + VMA_ITERATOR(vmi, current->mm, 0); > + > + vma = vma_next(&vmi); > + while (vma) { > + if (prev) > + prev_vm_end = prev->vm_end; > + if (vma->vm_start - prev_vm_end >= PAGE_SIZE) { > + if (is_reachable_by_call(prev_vm_end, vaddr)) > + return prev_vm_end; > + if (is_reachable_by_call(vma->vm_start - PAGE_SIZE, vaddr)) > + return vma->vm_start - PAGE_SIZE; > + } > + prev = vma; > + vma = vma_next(&vmi); > + } > + > + return 0; > +} This can be simplified afaics... We don't really need prev, and we can use for_each_vma(), static unsigned long find_nearest_page(unsigned long vaddr) { struct vm_area_struct *vma; unsigned long prev_vm_end = PAGE_SIZE; VMA_ITERATOR(vmi, current->mm, 0); for_each_vma(vmi, vma) { if (vma->vm_start - prev_vm_end >= PAGE_SIZE) { if (is_reachable_by_call(prev_vm_end, vaddr)) return prev_vm_end; if (is_reachable_by_call(vma->vm_start - PAGE_SIZE, vaddr)) return vma->vm_start - PAGE_SIZE; } prev_vm_end = vma->vm_end; } return 0; } > +static struct uprobe_trampoline *create_uprobe_trampoline(unsigned long vaddr) > +{ > + struct pt_regs *regs = task_pt_regs(current); > + struct mm_struct *mm = current->mm; > + struct uprobe_trampoline *tramp; > + struct vm_area_struct *vma; > + > + if (!user_64bit_mode(regs)) > + return NULL; Cosmetic, but I think it would be better to move this check into the caller, uprobe_trampoline_get(). > + vma = _install_special_mapping(mm, tramp->vaddr, PAGE_SIZE, > + VM_READ|VM_EXEC|VM_MAYEXEC|VM_MAYREAD|VM_DONTCOPY|VM_IO, > + &tramp_mapping); Note that xol_add_vma() -> _install_special_mapping() uses VM_SEALED_SYSMAP. Perhaps create_uprobe_trampoline() should use this flag too for consistency? Oleg.