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Message-ID:
<TYCPR01MB11269094C9E68404DE8A474A686212@TYCPR01MB11269.jpnprd01.prod.outlook.com>
Date: Wed, 6 Mar 2024 10:25:21 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Tim Pambor <tp@...systeme.de>, Geert Uytterhoeven
<geert+renesas@...der.be>
CC: Dragan Simic <dsimic@...jaro.org>, AnandMoon <linux.amoon@...il.com>,
Magnus Damm <magnus.damm@...il.com>, Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
<conor+dt@...nel.org>, "linux-renesas-soc@...r.kernel.org"
<linux-renesas-soc@...r.kernel.org>, "devicetree@...r.kernel.org"
<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] arm64: dts: r9a07g044: Add complete CPU cache information
Hi Tim Pambor,
> -----Original Message-----
> From: Tim Pambor <tp@...systeme.de>
> Sent: Wednesday, March 6, 2024 10:11 AM
> Subject: Re: [PATCH] arm64: dts: r9a07g044: Add complete CPU cache information
>
> Hi Biju,
>
> thanks for the review.
>
> > Hi Tim Pambor,
> >
> > Thanks for the patch.
> >
> > > -----Original Message-----
> > > From: Tim Pambor <tp@...systeme.de>
> > > Sent: Tuesday, March 5, 2024 3:14 PM
> > > Subject: [PATCH] arm64: dts: r9a07g044: Add complete CPU cache
> > > information
> > >
> > > Based on ARM Cortex-A55 TRM and RZG2/L user's manual, each Cortex-
> > > A55 has
> >
> > RZ/G2L
> >
> > > - 32 KB of L1 4-way, set-associative instruction cache
> > > - 32 KB of L1 4-way, set-associative data cache
> > >
> > > Each cache has a cache line length of 64B and therefore there are
> > > 32768B/(4 * 64B)=128 sets for each cache.
> > >
> > > RZG2/L are not configured with the optional per-core L2 cache but
> > > only have a L3 cache shared among all
> > RZ/G2L
> > > cores. In this case, the L3 cache appears as a L2 cache to the
> > > system. Therefore, specify "cache-level = <2>" for the L3 cache.
> >
>
> I will send a v2 with the commit message corrected.
>
> > You mean for L3 Cache, cache-level = <2> if there is no L2 Cache on
> > the system? Does it need any update on dt-bindings to make this clear?
>
> I followed the approach chosen for the Rockchip RK356x, which also has a Cortex-A55 with an L3 cache
> but no L2 cache [1]. I can add a comment to the device tree explaining that there is no L2 cache and
> that therefore the L3 cache appears as a L2 cache to the system. Do you consider that sufficient?
I am leaving this to Geert and other DT maintainer's for their view on this topic.
Cheers,
Biju
>
>
> Currently, having cache-level = <3> also causes a out-of-bounds access in populate_cache_leaves.
>
> [ 0.066217] ==================================================================
> [ 0.066369] BUG: KASAN: slab-out-of-bounds in populate_cache_leaves+0x25c/0x2d0
> [ 0.066495] Write of size 4 at addr ffff0000082370dc by task swapper/0/1
> [ 0.066580]
> [ 0.066619] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.8.0-rc2-00016-g30d5a685c65d #6
> [ 0.066719] Hardware name: MYC-YG2LX (DT)
> [ 0.066793] Call trace:
> [ 0.066836] dump_backtrace+0x98/0x118
> [ 0.066900] show_stack+0x18/0x24
> [ 0.066959] dump_stack_lvl+0x60/0xac
> [ 0.067029] print_report+0xf8/0x5d8
> [ 0.067096] kasan_report+0xc0/0x100
> [ 0.067159] __asan_report_store4_noabort+0x20/0x2c
> [ 0.067235] populate_cache_leaves+0x25c/0x2d0
> [ 0.067308] detect_cache_attributes+0x34c/0x1998
> [ 0.067384] update_siblings_masks+0x30/0x554
> [ 0.067460] store_cpu_topology+0xe8/0x188
> [ 0.067528] smp_prepare_cpus+0x5c/0x238
> [ 0.067602] kernel_init_freeable+0x258/0xb18
> [ 0.067673] kernel_init+0x30/0x208
> [ 0.067736] ret_from_fork+0x10/0x20
> [ 0.067802]
> [ 0.067835] Allocated by task 1:
> [ 0.067889] kasan_save_stack+0x3c/0x64
> [ 0.067956] kasan_save_track+0x20/0x3c
> [ 0.068020] kasan_save_alloc_info+0x68/0x78
> [ 0.068090] __kasan_kmalloc+0xd4/0xd8
> [ 0.068154] __kmalloc+0x1c0/0x430
> [ 0.068215] allocate_cache_info+0xa8/0x204
> [ 0.068284] fetch_cache_info+0xc4/0x200
> [ 0.068349] init_cpu_topology+0x348/0x45c
> [ 0.068423] smp_prepare_cpus+0x1c/0x238
> [ 0.068492] kernel_init_freeable+0x258/0xb18
> [ 0.068561] kernel_init+0x30/0x208
> [ 0.068622] ret_from_fork+0x10/0x20
> [ 0.068685]
> [ 0.068719] The buggy address belongs to the object at ffff000008237000
> [ 0.068719] which belongs to the cache kmalloc-256 of size 256
> [ 0.068849] The buggy address is located 4 bytes to the right of
> [ 0.068849] allocated 216-byte region [ffff000008237000, ffff0000082370d8)
> [ 0.068984]
> [ 0.069018] The buggy address belongs to the physical page:
> [ 0.069089] page:(____ptrval____) refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
> pfn:0x48236
> [ 0.069201] head:(____ptrval____) order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> [ 0.069297] flags: 0x840(slab|head|zone=0)
> [ 0.069366] page_type: 0xffffffff()
> [ 0.069430] raw: 0000000000000840 ffff000008001b40 dead000000000122 0000000000000000
> [ 0.069526] raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
> [ 0.069616] page dumped because: kasan: bad access detected
> [ 0.069684]
> [ 0.069717] Memory state around the buggy address:
> [ 0.069781] ffff000008236f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 0.069870] ffff000008237000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [ 0.069958] >ffff000008237080: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
> [ 0.070042] ^
> [ 0.070116] ffff000008237100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 0.070204] ffff000008237180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 0.070290] ==================================================================
>
> [1] https://lore.kernel.org/linux-
> rockchip/2285ee41e165813011220f9469e28697923aa6e0.1709491108.git.dsimic@...jaro.org/
>
> >
> > Cheers,
> > Biju
> >
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