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AJvYcCV+CXvYCtjOQd/cRSugcCHyepgoOKwJxq36uuJxP68zSMm+7X9/4plGmQdCOQrjPjE4dnRzkskd/Bh1cxxL@vger.kernel.org, AJvYcCV9EyKRjvV/4YeTSvPKtyktnzZDVlzkFtMSm47YUkKEOICczXrdqmYDCjrlFMGmTtxOoDE=@vger.kernel.org, AJvYcCWbgvaKbQpyOymhPWubnKgVWY4NounDaTUhw6W64BXmhoMVN8baQQ3xXh9bkbA8oT3yRfb+s3pkOiggsWLle6dYC9aO@vger.kernel.org X-Gm-Message-State: AOJu0YxPoJ6rZhua8C/yecD7cI9W1wx5CfhQEUzjHf+BNFHHwuvqRx8T 8RJW5aDZcUibwk4jERZWmK0d9+8919ZUOF5EgI9SxaoS8E/aWJ2OyXFtcmtn7oLLX20zJ1GpAC4 29qDyKijDvM9I7uQrui0f6cZunaolfg== X-Gm-Gg: ASbGnctc5GbVqpaJlCfrRARNsXW2GwMwuYcCWYXp198oFu8ZyhXyPGFKPX6Cuy7SqZl s8nymEa36Pcljn9pkEbCHH/69IrgAUF/9dDElZKvx3s8leGywWymadQ== X-Google-Smtp-Source: AGHT+IE4I6FX9eL+J0ZbDZaGKY7e3qXFxo9fK/76I8fjZvq8aCKbsGP+/8NinL+B99w6xPi9TEDieFTIArby7boWOw8= X-Received: by 2002:a17:90b:3c8a:b0:2ee:d193:f3d5 with SMTP id 98e67ed59e1d1-2f28fa5b800mr7207214a91.7.1734124303462; Fri, 13 Dec 2024 13:11:43 -0800 (PST) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241211133403.208920-1-jolsa@kernel.org> <20241211133403.208920-5-jolsa@kernel.org> In-Reply-To: From: Andrii Nakryiko Date: Fri, 13 Dec 2024 13:11:30 -0800 Message-ID: Subject: Re: [PATCH bpf-next 04/13] uprobes: Add arch_uprobe_verify_opcode function To: Jiri Olsa Cc: Oleg Nesterov , Peter Zijlstra , Andrii Nakryiko , bpf@vger.kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Dec 13, 2024 at 5:21=E2=80=AFAM Jiri Olsa wrot= e: > > On Thu, Dec 12, 2024 at 04:48:05PM -0800, Andrii Nakryiko wrote: > > On Wed, Dec 11, 2024 at 5:34=E2=80=AFAM Jiri Olsa wr= ote: > > > > > > Adding arch_uprobe_verify_opcode function, so we can overload > > > verification for each architecture in following changes. > > > > > > Signed-off-by: Jiri Olsa > > > --- > > > include/linux/uprobes.h | 5 +++++ > > > kernel/events/uprobes.c | 19 ++++++++++++++++--- > > > 2 files changed, 21 insertions(+), 3 deletions(-) > > > > > > diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h > > > index cc723bc48c1d..8843b7f99ed0 100644 > > > --- a/include/linux/uprobes.h > > > +++ b/include/linux/uprobes.h > > > @@ -215,6 +215,11 @@ extern void uprobe_handle_trampoline(struct pt_r= egs *regs); > > > extern void *arch_uretprobe_trampoline(unsigned long *psize); > > > extern unsigned long uprobe_get_trampoline_vaddr(void); > > > extern void uprobe_copy_from_page(struct page *page, unsigned long v= addr, void *dst, int len); > > > +extern int uprobe_verify_opcode(struct page *page, unsigned long vad= dr, uprobe_opcode_t *new_opcode); > > > +extern int arch_uprobe_verify_opcode(struct arch_uprobe *auprobe, st= ruct page *page, > > > + unsigned long vaddr, uprobe_opco= de_t *new_opcode, > > > + int nbytes); > > > +extern bool arch_uprobe_is_register(uprobe_opcode_t *insn, int nbyte= s); > > > #else /* !CONFIG_UPROBES */ > > > struct uprobes_state { > > > }; > > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > > > index 7c2ecf11a573..8068f91de9e3 100644 > > > --- a/kernel/events/uprobes.c > > > +++ b/kernel/events/uprobes.c > > > @@ -263,7 +263,13 @@ static void uprobe_copy_to_page(struct page *pag= e, unsigned long vaddr, const vo > > > kunmap_atomic(kaddr); > > > } > > > > > > -static int verify_opcode(struct page *page, unsigned long vaddr, upr= obe_opcode_t *new_opcode) > > > +__weak bool arch_uprobe_is_register(uprobe_opcode_t *insn, int nbyte= s) > > > +{ > > > + return is_swbp_insn(insn); > > > > a bit weird that we ignore nbytes here... should we have nbytes =3D=3D > > UPROBE_SWBP_INSN_SIZE check somewhere here or inside is_swbp_insn()? > > the original is_swbp_insn function does not need that and we need > nbytes in the overloaded arch_uprobe_is_register to distinguish > between 1 byte and 5 byte update.. > and that's my point, if some architecture forgot to override it for nop5 (or similar stuff), this default implementation should reject instruction that's not an original nop, no? > jirka > > > > > > +} > > > + > > > +int uprobe_verify_opcode(struct page *page, unsigned long vaddr, > > > + uprobe_opcode_t *new_opcode) > > > { > > > uprobe_opcode_t old_opcode; > > > bool is_swbp; > > > @@ -291,6 +297,13 @@ static int verify_opcode(struct page *page, unsi= gned long vaddr, uprobe_opcode_t > > > return 1; > > > } > > > > > > +__weak int arch_uprobe_verify_opcode(struct arch_uprobe *auprobe, st= ruct page *page, > > > + unsigned long vaddr, uprobe_opco= de_t *new_opcode, > > > + int nbytes) > > > +{ > > > + return uprobe_verify_opcode(page, vaddr, new_opcode); > > > > again, dropping nbytes on the floor here > > > > > +} > > > + > > > static struct delayed_uprobe * > > > delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) > > > { > > > @@ -479,7 +492,7 @@ int uprobe_write_opcode(struct arch_uprobe *aupro= be, struct mm_struct *mm, > > > bool orig_page_huge =3D false; > > > unsigned int gup_flags =3D FOLL_FORCE; > > > > > > - is_register =3D is_swbp_insn(insn); > > > + is_register =3D arch_uprobe_is_register(insn, nbytes); > > > uprobe =3D container_of(auprobe, struct uprobe, arch); > > > > > > retry: > > > @@ -490,7 +503,7 @@ int uprobe_write_opcode(struct arch_uprobe *aupro= be, struct mm_struct *mm, > > > if (IS_ERR(old_page)) > > > return PTR_ERR(old_page); > > > > > > - ret =3D verify_opcode(old_page, vaddr, insn); > > > + ret =3D arch_uprobe_verify_opcode(auprobe, old_page, vaddr, i= nsn, nbytes); > > > if (ret <=3D 0) > > > goto put_old; > > > > > > -- > > > 2.47.0 > > >