x86/cpu: Fix check for RDPKRU in __show_regs()
PATCH 1/1 x86/cpu: Fix check for RDPKRU in __show_regs()
From: David Kaplan <[email protected]>
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. ]
--- arch/x86/kernel/process_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/kernel/process_64.c +1 -1
@@ -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 ()); }
Signature · 1 line
2.43.0
The following commit has been merged into the x86/urgent branch of tip:
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: b53c6bd5d271d023857174b8fd3e32f98ae51372 Gitweb: https://git.kernel.org/tip/b53c6bd5d271d023857174b8fd3e32f98ae51372 Author: David Kaplan <[email protected]> AuthorDate: Sun, 21 Apr 2024 21:17:28 +02:00 Committer: Borislav Petkov (AMD) <[email protected]> CommitterDate: Wed, 24 Apr 2024 14:30:21 +02:00
x86/cpu: Fix check for RDPKRU in __show_regs()
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. ]
--- arch/x86/kernel/process_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/kernel/process_64.c +1 -1
@@ -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 ()); }