From: Sergey Matyukevich <geomatsi@gmail.com>
To: linux-riscv@lists.infradead.org
Cc: Anup Patel <anup@brainfault.org>,
Atish Patra <atishp@rivosinc.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Samuel Holland <samuel.holland@sifive.com>,
Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Subject: [PATCH] riscv: prevent pt_regs corruption for secondary idle threads
Date: Thu, 25 Apr 2024 01:19:23 +0300 [thread overview]
Message-ID: <20240424221927.900612-1-geomatsi@gmail.com> (raw)
From: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Top of the kernel thread stack should be reserved for pt_regs. However
this is not the case for the idle threads of the secondary boot harts.
Their stacks overlap with their pt_regs, so both may get corrupted.
Similar issue has been fixed for the primary hart, see c7cdd96eca29
("riscv: prevent stack corruption by reserving task_pt_regs(p) early").
However that fix was not propagated to the secondary harts. The problem
has been noticed in some CPU hotplug tests with V enabled. The function
smp_callin stores several registers on stack, corrupting top of pt_regs
structure including status field. As a result, kernel attempted to save
or restore inexistent V context.
Fixes: 9a2451f18663 ("RISC-V: Avoid using per cpu array for ordered booting")
Fixes: 2875fe056156 ("RISC-V: Add cpu_ops and modify default booting method")
Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
---
arch/riscv/kernel/cpu_ops_sbi.c | 2 +-
arch/riscv/kernel/cpu_ops_spinwait.c | 3 +--
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/kernel/cpu_ops_sbi.c b/arch/riscv/kernel/cpu_ops_sbi.c
index 1cc7df740edd..e6fbaaf54956 100644
--- a/arch/riscv/kernel/cpu_ops_sbi.c
+++ b/arch/riscv/kernel/cpu_ops_sbi.c
@@ -72,7 +72,7 @@ static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
/* Make sure tidle is updated */
smp_mb();
bdata->task_ptr = tidle;
- bdata->stack_ptr = task_stack_page(tidle) + THREAD_SIZE;
+ bdata->stack_ptr = task_pt_regs(tidle);
/* Make sure boot data is updated */
smp_mb();
hsm_data = __pa(bdata);
diff --git a/arch/riscv/kernel/cpu_ops_spinwait.c b/arch/riscv/kernel/cpu_ops_spinwait.c
index 613872b0a21a..24869eb88908 100644
--- a/arch/riscv/kernel/cpu_ops_spinwait.c
+++ b/arch/riscv/kernel/cpu_ops_spinwait.c
@@ -34,8 +34,7 @@ static void cpu_update_secondary_bootdata(unsigned int cpuid,
/* Make sure tidle is updated */
smp_mb();
- WRITE_ONCE(__cpu_spinwait_stack_pointer[hartid],
- task_stack_page(tidle) + THREAD_SIZE);
+ WRITE_ONCE(__cpu_spinwait_stack_pointer[hartid], task_pt_regs(tidle));
WRITE_ONCE(__cpu_spinwait_task_pointer[hartid], tidle);
}
--
2.44.0
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next reply other threads:[~2024-04-24 22:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-24 22:19 Sergey Matyukevich [this message]
2024-05-13 12:19 ` [PATCH] riscv: prevent pt_regs corruption for secondary idle threads Sergey Matyukevich
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=20240424221927.900612-1-geomatsi@gmail.com \
--to=geomatsi@gmail.com \
--cc=anup@brainfault.org \
--cc=aou@eecs.berkeley.edu \
--cc=atishp@rivosinc.com \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=samuel.holland@sifive.com \
--cc=sergey.matyukevich@syntacore.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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).