On Thu, Dec 12, 2024 at 04:48:05PM -0800, Andrii Nakryiko wrote:
> On Wed, Dec 11, 2024 at 5:34 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >
> > Adding arch_uprobe_verify_opcode function, so we can overload
> > verification for each architecture in following changes.
> >
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > 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_regs *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 vaddr, void *dst, int len);
> > +extern int uprobe_verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode);
> > +extern int arch_uprobe_verify_opcode(struct arch_uprobe *auprobe, struct page *page,
> > + unsigned long vaddr, uprobe_opcode_t *new_opcode,
> > + int nbytes);
> > +extern bool arch_uprobe_is_register(uprobe_opcode_t *insn, int nbytes);
> > #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 *page, unsigned long vaddr, const vo
> > kunmap_atomic(kaddr);
> > }
> >
> > -static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
> > +__weak bool arch_uprobe_is_register(uprobe_opcode_t *insn, int nbytes)
> > +{
> > + return is_swbp_insn(insn);
>
> a bit weird that we ignore nbytes here... should we have nbytes ==
> 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..
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, unsigned long vaddr, uprobe_opcode_t
> > return 1;
> > }
> >
> > +__weak int arch_uprobe_verify_opcode(struct arch_uprobe *auprobe, struct page *page,
> > + unsigned long vaddr, uprobe_opcode_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 *auprobe, struct mm_struct *mm,
> > bool orig_page_huge = false;
> > unsigned int gup_flags = FOLL_FORCE;
> >
> > - is_register = is_swbp_insn(insn);
> > + is_register = arch_uprobe_is_register(insn, nbytes);
> > uprobe = container_of(auprobe, struct uprobe, arch);
> >
> > retry:
> > @@ -490,7 +503,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
> > if (IS_ERR(old_page))
> > return PTR_ERR(old_page);
> >
> > - ret = verify_opcode(old_page, vaddr, insn);
> > + ret = arch_uprobe_verify_opcode(auprobe, old_page, vaddr, insn, nbytes);
> > if (ret <= 0)
> > goto put_old;
> >
> > --
> > 2.47.0
> >
