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Message-Id: <a967eb54-9c54-f9a7-f92a-0ae3d8eb60ba@de.ibm.com>
Date: Tue, 17 Apr 2018 10:24:35 +0200
From: Christian Borntraeger <borntraeger@...ibm.com>
To: Thomas Richter <tmricht@...ux.ibm.com>, jeyu@...nel.org,
torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Cc: schwidefsky@...ibm.com, brueckner@...ux.vnet.ibm.com,
heiko.carstens@...ibm.com, peterz@...radead.org, acme@...nel.org,
me@...in.cc, keescook@...omium.org
Subject: Re: [PATCH] modules: Fix display of wrong module .text address
On 04/17/2018 10:20 AM, Thomas Richter wrote:
> In kernel v4.16.0 the module .text address is displayed
> wrong when using /sys/module/*/sections/.text file.
> Commit ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when
> not restricting")
> is the first bad commit.
>
> Here is the issue, using module qeth_l2 on s390 which is the
> ethernet device driver:
>
> [root@...lp76 ~]# lsmod
> Module Size Used by
> qeth_l2 94208 1
> ...
>
> [root@...lp76 ~]# cat /proc/modules | egrep '^qeth_l2'
> qeth_l2 94208 1 - Live 0x000003ff80401000
> ^ This is the correct address in memory
> [root@...lp76 ~]# cat /sys/module/qeth_l2/sections/.text
> 0x0000000018ea8363 <---- This is a wrong address
> [root@...lp76 ~]#
>
> This breaks the perf tool which uses this address on s390
> to calculate start of .text section in memory.
>
> Fix this by printing the correct (unhashed) address.
>
> Thanks to Jessica Yu for helping on this.
>
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
> Cc: Jessica Yu <jeyu@...nel.org>
CC stable?
> ---
> kernel/module.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index a6e43a5806a1..77ab7211ddef 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1472,7 +1472,7 @@ static ssize_t module_sect_show(struct module_attribute *mattr,
> {
> struct module_sect_attr *sattr =
> container_of(mattr, struct module_sect_attr, mattr);
> - return sprintf(buf, "0x%pK\n", (void *)sattr->address);
> + return sprintf(buf, "%#lx\n", kptr_restrict < 2 ? sattr->address : 0);
> }
>
> static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
>
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