[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240421191728.32239-1-bp@kernel.org>
Date: Sun, 21 Apr 2024 21:17:28 +0200
From: bp@...nel.org
To: X86 ML <x86@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
David Kaplan <david.kaplan@....com>,
Borislav Petkov <bp@...en8.de>
Subject: [PATCH] x86/cpu: Fix check for RDPKRU in __show_regs()
From: David Kaplan <david.kaplan@....com>
cpu_feature_enabled(X86_FEATURE_OSPKE) does not necessarily reflect
whether CR4.PKE is set on the CPU. In particular, they may differ on
non-BSP CPUs before setup_pku() is executed. In this scenario, RDPKRU
will #UD causing the system to hang.
Fix by checking CR4 for PKE enablement which is always correct for the
current CPU.
The scenario happens by inserting a WARN* before setup_pku() in
identiy_cpu() or some other diagnostic which would lead to calling
__show_regs().
[ bp: Massage commit message. ]
Signed-off-by: David Kaplan <david.kaplan@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
arch/x86/kernel/process_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 7062b84dd467..6d3d20e3e43a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -139,7 +139,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode,
log_lvl, d3, d6, d7);
}
- if (cpu_feature_enabled(X86_FEATURE_OSPKE))
+ if (cr4 & X86_CR4_PKE)
printk("%sPKRU: %08x\n", log_lvl, read_pkru());
}
--
2.43.0
Powered by blists - more mailing lists