Re: [RESEND PATCH v5] arm64: Enable vmalloc-huge with ptdump

[Dev Jain]

On 19/09/25 4:29 pm, Will Deacon wrote:
> On Fri, Sep 19, 2025 at 03:58:46PM +0530, Dev Jain wrote:
> > On 17/09/25 9:13 pm, Will Deacon wrote:
> > > On Tue, Sep 16, 2025 at 11:30:26AM +0100, Will Deacon wrote:
> > > > I'm currently trying to put together a litmus test with James (cc'd) so
> > > > maybe we can help you out with that part.
> > > Here's what we came up with. There's not a good way to express the IPI
> > > from kick_all_cpus_sync() but it turns out that the ISB from the TLB
> > > invalidation is sufficient anyway. Does it make sense to you?
> > >
> > >
> > > AArch64 ptdump
> > > Variant=Ifetch
> > > {
> > > uint64_t pud=0xa110c;
> > > uint64_t pmd;
> > >
> > > 0:X0=label:"P1:L0"; 0:X1=instr:"NOP"; 0:X2=lock; 0:X3=pud; 0:X4=pmd;
> > >                       1:X1=0xdead;      1:X2=lock; 1:X3=pud; 1:X4=pmd;
> > > }
> > >    P0				| P1				;
> > >    (* static_key_enable *)	| (* pud_free_pmd_page *)	;
> > >    STR	W1, [X0]		| LDR	X9, [X3]		;
> > >    DC	CVAU,X0			| STR	XZR, [X3]		;
> > >    DSB	ISH			| DSB	ISH			;
> > >    IC	IVAU,X0			| ISB				;
> > >    DSB	ISH			|				;
> > >    ISB				| (* static key *)		;
> > > 				| L0:				;
> > >    (* mmap_lock *)		| B	out1			;
> > >    Lwlock:			|				;
> > >    MOV	W7, #1			| (* mmap_lock *)		;
> > >    SWPA	W7, W8, [X2]		| Lrlock:			;
> > > 				| MOV	W7, #1			;
> > > 				| SWPA	W7, W8, [X2]		;
> > >    (* walk pgtable *)		|				;
> > >    LDR	X9, [X3]		| (* mmap_unlock *)		;
> > >    CBZ	X9, out0		| STLR	WZR, [X2]		;
> > >    EOR	X10, X9, X9		|				;
> > >    LDR	X11, [X4, X10]		| out1:				;
> > > 				| EOR	X10, X9, X9		;
> > >    out0:				| STR	X1, [X4, X10]		;
> > >
> > > exists (0:X8=0 /\ 1:X8=0 /\	(* Lock acquisitions succeed *)
> > > 	0:X9=0xa110c /\		(* P0 sees the valid PUD ...*)
> > > 	0:X11=0xdead)		(* ... but the freed PMD *)
> > >
> > >
> > > Will
> > Is the syntax correct? I cannot use the herd7 command to run this.
> Weird, what happens? It runs for me:
>
> $ herd7 -version
> 7.58+1, Rev: e39a86f5d59dee3174d08d9ab5b13155c75936fd
>
> $ herd7 ptdump.litmus
> Test ptdump Allowed
> States 5
> 0:X8=0; 0:X9=0; 0:X11=0; 1:X8=0;
> 0:X8=0; 0:X9=0; 0:X11=0; 1:X8=1;
> 0:X8=0; 0:X9=659724; 0:X11=0; 1:X8=1;
> 0:X8=0; 0:X9=659724; 0:X11=57005; 1:X8=1;
> 0:X8=1; 0:X9=0; 0:X11=0; 1:X8=0;
> No
> Witnesses
> Positive: 0 Negative: 9
> Flag Assuming-common-inner-shareable-domain
> Condition exists (0:X8=0 /\ 1:X8=0 /\ 0:X9=659724 /\ 0:X11=57005)
> Observation ptdump Never 0 9
> Time ptdump 1.65
> Hash=238908ee9413a36507c61b92a31a366a

I was using some other command :) yup this works.

I'll try posting the next version today itself, but will you be
okay merging this if I post on Monday?

> Will