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[85.193.35.215]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42286fe9230sm269539285e9.17.2024.06.19.09.22.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 09:22:14 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 19 Jun 2024 18:22:12 +0200 To: Liao Chang Cc: rostedt@goodmis.org, mhiramat@kernel.org, oleg@redhat.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, nathan@kernel.org, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH bpf-next] uprobes: Fix the xol slots reserved for uretprobe trampoline Message-ID: References: <20240619013411.756995-1-liaochang1@huawei.com> Precedence: bulk X-Mailing-List: linux-perf-users@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: <20240619013411.756995-1-liaochang1@huawei.com> On Wed, Jun 19, 2024 at 01:34:11AM +0000, Liao Chang wrote: > When the new uretprobe system call was added [1], the xol slots reserved > for the uretprobe trampoline might be insufficient on some architecture. hum, uretprobe syscall is x86_64 specific, nothing was changed wrt slots or other architectures.. could you be more specific in what's changed? thanks, jirka > For example, on arm64, the trampoline is consist of three instructions > at least. So it should mark enough bits in area->bitmaps and > and area->slot_count for the reserved slots. > > [1] https://lore.kernel.org/all/20240611112158.40795-4-jolsa@kernel.org/ > > Signed-off-by: Liao Chang > --- > kernel/events/uprobes.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 2816e65729ac..efd2d7f56622 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -1485,7 +1485,7 @@ void * __weak arch_uprobe_trampoline(unsigned long *psize) > static struct xol_area *__create_xol_area(unsigned long vaddr) > { > struct mm_struct *mm = current->mm; > - unsigned long insns_size; > + unsigned long insns_size, slot_nr; > struct xol_area *area; > void *insns; > > @@ -1508,10 +1508,13 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) > > area->vaddr = vaddr; > init_waitqueue_head(&area->wq); > - /* Reserve the 1st slot for get_trampoline_vaddr() */ > - set_bit(0, area->bitmap); > - atomic_set(&area->slot_count, 1); > insns = arch_uprobe_trampoline(&insns_size); > + /* Reserve enough slots for the uretprobe trampoline */ > + for (slot_nr = 0; > + slot_nr < max((insns_size / UPROBE_XOL_SLOT_BYTES), 1); > + slot_nr++) > + set_bit(slot_nr, area->bitmap); > + atomic_set(&area->slot_count, slot_nr); > arch_uprobe_copy_ixol(area->pages[0], 0, insns, insns_size); > > if (!xol_add_vma(mm, area)) > -- > 2.34.1 >