Date: Wed, 17 Feb 2010 09:44:44 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: gjb@semihalf.com Cc: freebsd-arm@FreeBSD.org Subject: Re: kdump on ARM Message-ID: <20100217.094444.4959786828202967.imp@bsdimp.com> In-Reply-To: <4B7BFAA4.4040607@semihalf.com> References: <4B7BFAA4.4040607@semihalf.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In message: <4B7BFAA4.4040607@semihalf.com>
Grzegorz Bernacki <gjb@semihalf.com> writes:
: Hi,
:
: I've noticed that kdump on ARM doesn't work properly, it generates bus
: error. The problem is that structures dumped into ktrace.out are not
: aligned. Processing such a structure causes Aligment Fault. One
: solution is to copy structure into local variable and then process it,
: please see patch below. But I am not sure if this is the best solution
: and maybe someone has a better idea.
:
: grzesiek
:
:
: diff --git a/usr.bin/kdump/kdump.c b/usr.bin/kdump/kdump.c
: index 386221e..5a15886 100644
: --- a/usr.bin/kdump/kdump.c
: +++ b/usr.bin/kdump/kdump.c
: @@ -1325,6 +1325,10 @@ ktrstat(struct stat *statp)
: void
: ktrstruct(char *buf, size_t buflen)
: {
: +#if defined(__arm__)
: + struct stat stat;
: + struct sockaddr sockaddr;
: +#endif
Lose the ifdefs. Also, sockaddr is the wrong structure, it should be
sockaddr_storage.
: char *name, *data;
: size_t namelen, datalen;
: int i;
: @@ -1348,12 +1352,22 @@ ktrstruct(char *buf, size_t buflen)
: if (strcmp(name, "stat") == 0) {
: if (datalen != sizeof(struct stat))
: goto invalid;
: +#if defined(__arm__)
: + memcpy(&stat, data, sizeof(struct stat));
: + ktrstat(&stat);
: +#else
: ktrstat((struct stat *)data);
: +#endif
This is needlessly complicated. Replace with:
stat = *(struct stat *)data;
ktrstat(&stat);
: } else if (strcmp(name, "sockaddr") == 0) {
: if (datalen < sizeof(struct sockaddr) ||
: datalen != ((struct sockaddr *)(data))->sa_len)
: goto invalid;
: +#if defined(__arm__)
: + memcpy(&sockaddr, data, sizeof(struct sockaddr));
: + ktrsockaddr(&sockaddr);
: +#else
: ktrsockaddr((struct sockaddr *)data);
: +#endif
This is actually wrong. You're only copying part of the structure and
it will be wrong for IPv6 addresses. Consider
memcpy(&sockaddr, data, datalen);
ktrsockaddr(&sockaddr);
instead. However, this is already too late. We've already
dereferenced through data in its unaligned state.
Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20100217.094444.4959786828202967.imp>