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From:   Haibo Li <haibo.li@mediatek.com>
To:     <linus.walleij@linaro.org>
CC:     <a.anurag@samsung.com>, <alexander.sverdlin@nokia.com>,
        <amergnat@baylibre.com>, <angelogioacchino.delregno@collabora.com>,
        <ardb@kernel.org>, <catalin.marinas@arm.com>,
        <haibo.li@mediatek.com>, <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-mediatek@lists.infradead.org>, <linux@armlinux.org.uk>,
        <matthias.bgg@gmail.com>, <rmk+kernel@armlinux.org.uk>,
        <xiaoming.yu@mediatek.com>
Subject: Re: [PATCH v3] ARM:unwind:fix unwind abort for uleb128 case
Date:   Mon, 17 Apr 2023 17:46:38 +0800
Message-ID: <20230417094638.153213-1-haibo.li@mediatek.com>
In-Reply-To: <CACRpkdZf0vQL9bJtGaKfn0wBPTQTZWsg0G7UTB1dmXhfi_2KmA@mail.gmail.com>
References: <CACRpkdZf0vQL9bJtGaKfn0wBPTQTZWsg0G7UTB1dmXhfi_2KmA@mail.gmail.com>
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> On Fri, Apr 14, 2023 at 8:10 AM Haibo Li <haibo.li@mediatek.com> wrote:=0D
> =0D
> > When unwind instruction is 0xb2,the subsequent instructions are=0D
> > uleb128 bytes.=0D
> > For now,it uses only the first uleb128 byte in code.=0D
> >=0D
> > For vsp increments of 0x204~0x400,use one uleb128 byte like below:=0D
> > 0xc06a00e4 <unwind_test_work>: 0x80b27fac=0D
> >   Compact model index: 0=0D
> >   0xb2 0x7f vsp =3D vsp + 1024=0D
> >   0xac      pop {r4, r5, r6, r7, r8, r14}=0D
> >=0D
> > For vsp increments larger than 0x400,use two uleb128 bytes like below:=
=0D
> > 0xc06a00e4 <unwind_test_work>: @0xc0cc9e0c=0D
> >   Compact model index: 1=0D
> >   0xb2 0x81 0x01 vsp =3D vsp + 1032=0D
> >   0xac      pop {r4, r5, r6, r7, r8, r14}=0D
> > The unwind works well since the decoded uleb128 byte is also 0x81.=0D
> >=0D
> > For vsp increments larger than 0x600,use two uleb128 bytes like below:=
=0D
> > 0xc06a00e4 <unwind_test_work>: @0xc0cc9e0c=0D
> >   Compact model index: 1=0D
> >   0xb2 0x81 0x02 vsp =3D vsp + 1544=0D
> >   0xac      pop {r4, r5, r6, r7, r8, r14}=0D
> > In this case,the decoded uleb128 result is 0x101(vsp=3D0x204+(0x101<<2)=
).=0D
> > While the uleb128 used in code is 0x81(vsp=3D0x204+(0x81<<2)).=0D
> > The unwind aborts at this frame since it gets incorrect vsp.=0D
> >=0D
> > To fix this,add uleb128 decode to cover all the above case.=0D
> >=0D
> > Signed-off-by: Haibo Li <haibo.li@mediatek.com>=0D
> =0D
> Way to go, remember to collect all the Reviewed-by tags before you put th=
e=0D
> patch into Russell's patch tracker.=0D
> =0D
> Yours,=0D
> Linus Walleij=0D
Thanks for reminding.I put the patch into Russell's patch tracker just now,=
=0D
together with the three Reviewed-by tags from you,=0D
Alexandre Mergnat and AngeloGioacchino Del Regno.=0D
Thank you all.=0D
=0D