Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
From:   Masahiro Yamada <masahiroy@kernel.org>
To:     Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
        xen-devel@lists.xenproject.org (moderated for non-subscribers)
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Julien Grall <julien.grall@arm.com>,
        Shannon Zhao <shannon.zhao@linaro.org>,
        linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org
Subject: [PATCH] xen: unexport __init-annotated xen_xlate_map_ballooned_pages()
Date:   Mon,  6 Jun 2022 13:59:20 +0900
Message-Id: <20220606045920.4161881-1-masahiroy@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because none of the in-tree call-sites
(arch/arm/xen/enlighten.c, arch/x86/xen/grant-table.c) is compiled as
modular.

Fixes: 243848fc018c ("xen/grant-table: Move xlated_setup_gnttab_pages to common place")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 drivers/xen/xlate_mmu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c
index 34742c6e189e..f17c4c03db30 100644
--- a/drivers/xen/xlate_mmu.c
+++ b/drivers/xen/xlate_mmu.c
@@ -261,7 +261,6 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(xen_xlate_map_ballooned_pages);
 
 struct remap_pfn {
 	struct mm_struct *mm;
-- 
2.32.0