[LTP] [PATCH] syscalls/ptrace08: Add another linux tag

[Li Wang]

On Mon, Nov 2, 2020 at 2:28 PM Yang Xu <xuyang2018.jy@cn.fujitsu.com> wrote:

> Since "syscall/ptrace08: Simplify the test", on older kernels we check
> that the
> POKEUSER to dr7 that enables the breakpoint fails properly after the dr0
> has been
> set to an address in the kernel range.
>
> on centos7.8GA, it can expose a failure as below:
> tst_test.c:1250: TINFO: Timeout per run is 0h 05m 00s
> tst_kernel.c:79: TINFO: uname.machine=x86_64 kernel is 64bit
> ptrace08.c:90: TINFO: Trying address 0xffff800000000000
> ptrace08.c:120: TPASS: ptrace() breakpoint with kernel addr failed: EINVAL
> (22)
> ptrace08.c:129: TINFO: 0xffff800000000000
> ptrace08.c:90: TINFO: Trying address 0xffffffffffffffff
> ptrace08.c:116: TFAIL: ptrace() breakpoint with kernel addr succeeded
> ptrace08.c:129: TINFO: 0xffffffffffffffff
> ptrace08.c:90: TINFO: Trying address 0xffffbfffffffffff
> ptrace08.c:120: TPASS: ptrace() breakpoint with kernel addr failed: EINVAL
> (22)
> ptrace08.c:129: TINFO: 0xffffbfffffffffff
>
> It fails because x86 hw_breakpoint code can't parse this
> 0xffffffffffffffff kernel
> address on x86_64 platform.
>
> arch/x86/kernel/hw_breakpoint.c
>  int arch_check_bp_in_kernelspace(struct perf_event *bp)
>         return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
>
> TASK_SIZE is small and value will overflow if we use 0xffffffffffffffff
> address
> (va is unsigned long and len is unsigned int).
>
> Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
>

Patch applied. Thanks!

-- 
Regards,
Li Wang
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