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From:   Nadav Amit <namit@vmware.com>
To:     Matt Mullins <mmullins@fb.com>
CC:     Borislav Petkov <bp@alien8.de>,
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        Christophe Leroy <christophe.leroy@c-s.fr>,
        Douglas Anderson <dianders@chromium.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/kgdb: return 0 from kgdb_arch_set_breakpoint
Thread-Topic: [PATCH] x86/kgdb: return 0 from kgdb_arch_set_breakpoint
Thread-Index: AQHVF+nqHaBESOu01Eao/K0uaC2yhaaFpLcA
Date:   Fri, 31 May 2019 19:51:44 +0000
Message-ID: <F51E9CDD-6936-46B8-967D-13F6BFEF8CE0@vmware.com>
References: <20190531194755.6320-1-mmullins@fb.com>
In-Reply-To: <20190531194755.6320-1-mmullins@fb.com>
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> On May 31, 2019, at 12:47 PM, Matt Mullins <mmullins@fb.com> wrote:
>=20
> err must be nonzero in order to reach text_poke(), which caused kgdb to
> fail to set breakpoints:
>=20
> 	(gdb) break __x64_sys_sync
> 	Breakpoint 1 at 0xffffffff81288910: file ../fs/sync.c, line 124.
> 	(gdb) c
> 	Continuing.
> 	Warning:
> 	Cannot insert breakpoint 1.
> 	Cannot access memory at address 0xffffffff81288910
>=20
> 	Command aborted.
>=20
> Fixes: 86a22057127d ("x86/kgdb: Avoid redundant comparison of patched cod=
e")
> Signed-off-by: Matt Mullins <mmullins@fb.com>
> ---
> arch/x86/kernel/kgdb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
> index 9a8c1648fc9a..6690c5652aeb 100644
> --- a/arch/x86/kernel/kgdb.c
> +++ b/arch/x86/kernel/kgdb.c
> @@ -758,7 +758,7 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
> 		       BREAK_INSTR_SIZE);
> 	bpt->type =3D BP_POKE_BREAKPOINT;
>=20
> -	return err;
> +	return 0;
> }
>=20
> int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
> --=20
> 2.17.1

My bad. Thanks for fixing it.

Reviewed-by: Nadav Amit <namit@vmware.com>