linux-kernel - Re: [PATCH] ARM: ptrace: fix scno of -1 cause SIGILL

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Message-ID: <20230807075309.6188-1-lecopzer.chen@mediatek.com>
Date:   Mon, 7 Aug 2023 15:53:09 +0800
From:   Lecopzer Chen <lecopzer.chen@...iatek.com>
To:     <lecopzer.chen@...iatek.com>
CC:     <arnd@...db.de>, <linus.walleij@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux@...linux.org.uk>,
        <yj.chiang@...iatek.com>
Subject: Re: [PATCH] ARM: ptrace: fix scno of -1 cause SIGILL


> In commit [1], the -1 scno is used as a special scno when the task's
> syscall is traced.

> After commit [2], PTRACE_SET_SYSCALL will always mask syscall with
> __NR_SYSCALL_MASK, this makes the condition `cmp scno, #-1` broken,
> and some test like Android VTS[3] is also failed because SIGILL
> interrupt the test program.

> Let's test with `and` logic with #0x0ff000. Instead of #__NR_SYSCALL_MASK
> because of the constraint of ARM Operand2 rules and avoid conflicting
> with ARM private syscall.

...

Please follow the commit from Kees below and ignore this patch, thanks.

https://lore.kernel.org/all/20230804071045.never.134-kees@kernel.org/