From: Baoquan He <bhe@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: kirill.shutemov@linux.intel.com, tglx@linutronix.de,
mingo@kernel.org, bp@alien8.de, hpa@zytor.com, dyoung@redhat.com,
x86@kernel.org, Baoquan He <bhe@redhat.com>
Subject: [PATCH v3 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel
Date: Tue, 12 Mar 2019 18:30:50 +0800 [thread overview]
Message-ID: <20190312103051.18086-3-bhe@redhat.com> (raw)
In-Reply-To: <20190312103051.18086-1-bhe@redhat.com>
In relocate_kernel() CR4.LA57 flag is set before kexec jumping if
the kernel has 5-level paging enabled. Then in boot/compressed/head_64.S,
it will check if the booting kernel is in 4-level or 5-level paging
mode, and handle accordingly. However, the old kernel which doesn't
contain the 5-level codes doesn't know how to cope with it, then #GP
triggered.
Instead of triggering #GP during kexec kernel boot, error out during
kexec loading if find out we are trying to jump to old 4-level kernel
from 5-level kernel.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/kernel/kexec-bzimage64.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 1f3b77367948..4c9c079b5673 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -321,6 +321,11 @@ static int bzImage64_probe(const char *buf, unsigned long len)
return ret;
}
+ if (!(header->xloadflags & XLF_5LEVEL) && pgtable_l5_enabled()) {
+ pr_err("Can not jump to old 4-level kernel from 5-level kernel.\n");
+ return ret;
+ }
+
/* I've got a bzImage */
pr_debug("It's a relocatable bzImage64\n");
ret = 0;
--
2.17.2
next prev parent reply other threads:[~2019-03-12 10:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-12 10:30 [PATCH v3 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel Baoquan He
2019-03-12 10:30 ` [PATCH v3 1/3] x86/boot: Add xloadflags bits for 5-level kernel checking Baoquan He
2019-04-05 20:23 ` Thomas Gleixner
2019-04-06 1:40 ` Baoquan He
2019-03-12 10:30 ` Baoquan He [this message]
2019-04-05 20:38 ` [PATCH v3 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Thomas Gleixner
2019-04-06 1:39 ` Baoquan He
2019-03-12 10:30 ` [PATCH v3 3/3] x86/kdump/64: Change the upper limit of crashkernel reservation Baoquan He
2019-04-04 2:20 ` [PATCH v3 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel Baoquan He
2019-04-06 1:43 ` Baoquan He
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