From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Sasha Levin <sashal@kernel.org>,
mpe@ellerman.id.au, christophe.leroy@csgroup.eu, aik@ozlabs.ru,
amodra@au1.ibm.com, dja@axtens.net,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH AUTOSEL 5.15 10/21] powerpc/64: don't refer nr_cpu_ids in asm code when it's undefined
Date: Mon, 17 Oct 2022 20:09:29 -0400 [thread overview]
Message-ID: <20221018000940.2731329-10-sashal@kernel.org> (raw)
In-Reply-To: <20221018000940.2731329-1-sashal@kernel.org>
From: Yury Norov <yury.norov@gmail.com>
[ Upstream commit 546a073d628111e3338af689938407e77d5dc38f ]
generic_secondary_common_init() calls LOAD_REG_ADDR(r7, nr_cpu_ids)
conditionally on CONFIG_SMP. However, if 'NR_CPUS == 1', kernel doesn't
use the nr_cpu_ids, and in C code, it's just:
#if NR_CPUS == 1
#define nr_cpu_ids
...
This series makes declaration of nr_cpu_ids conditional on NR_CPUS == 1,
and that reveals the issue, because compiler can't link the
LOAD_REG_ADDR(r7, nr_cpu_ids) against nonexisting symbol.
Current code looks unsafe for those who build kernel with CONFIG_SMP=y and
NR_CPUS == 1. This is weird configuration, but not disallowed.
Fix the linker error by replacing LOAD_REG_ADDR() with LOAD_REG_IMMEDIATE()
conditionally on NR_CPUS == 1.
As the following patch adds CONFIG_FORCE_NR_CPUS option that has the
similar effect on nr_cpu_ids, make the generic_secondary_common_init()
conditional on it too.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/kernel/head_64.S | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index f17ae2083733..1cfb9be1ca9b 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -400,8 +400,12 @@ generic_secondary_common_init:
#else
LOAD_REG_ADDR(r8, paca_ptrs) /* Load paca_ptrs pointe */
ld r8,0(r8) /* Get base vaddr of array */
+#if (NR_CPUS == 1) || defined(CONFIG_FORCE_NR_CPUS)
+ LOAD_REG_IMMEDIATE(r7, NR_CPUS)
+#else
LOAD_REG_ADDR(r7, nr_cpu_ids) /* Load nr_cpu_ids address */
lwz r7,0(r7) /* also the max paca allocated */
+#endif
li r5,0 /* logical cpu id */
1:
sldi r9,r5,3 /* get paca_ptrs[] index from cpu id */
--
2.35.1
next prev parent reply other threads:[~2022-10-18 0:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 0:09 [PATCH AUTOSEL 5.15 01/21] crypto: qcom-rng - Fix qcom_rng_of_match unused warning Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 02/21] crypto: ccp - Add a quirk to firmware update Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 03/21] gfs2: Switch from strlcpy to strscpy Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 04/21] powerpc/hw_breakpoint: Avoid relying on caller synchronization Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 05/21] cgroup: Remove data-race around cgrp_dfl_visible Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 06/21] of/fdt: Don't calculate initrd size from DT if start > end Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 07/21] objtool,x86: Teach decode about LOOP* instructions Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 08/21] locking/rwsem: Disable preemption while trying for rwsem lock Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 09/21] gfs2: Check sb_bsize_shift after reading superblock Sasha Levin
2022-10-18 0:09 ` Sasha Levin [this message]
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 11/21] m68knommu: fix non-specific 68328 choice interrupt build failure Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 12/21] m68knommu: fix non-mmu classic 68000 legacy timer tick selection Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 13/21] of: Fix "dma-ranges" handling for bus controllers Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 14/21] x86/hyperv: Replace kmap() with kmap_local_page() Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 15/21] kmsan: disable instrumentation of unsupported common kernel code Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 16/21] kmsan: disable physical page merging in biovec Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 17/21] f2fs: fix to detect corrupted meta ino Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 18/21] 9p: trans_fd/p9_conn_cancel: drop client lock earlier Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 19/21] 9p/trans_fd: always use O_NONBLOCK read/write Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 20/21] net/9p: use a dedicated spinlock for trans_fd Sasha Levin
2022-10-18 0:09 ` [PATCH AUTOSEL 5.15 21/21] virtio_pci: don't try to use intxif pin is zero Sasha Levin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20221018000940.2731329-10-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=aik@ozlabs.ru \
--cc=amodra@au1.ibm.com \
--cc=christophe.leroy@csgroup.eu \
--cc=dja@axtens.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=sfr@canb.auug.org.au \
--cc=stable@vger.kernel.org \
--cc=yury.norov@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox