linux-kernel - [tip: x86/fred] x86/fred: Make exc_page

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Message-ID: <170668567825.398.12991014894719583005.tip-bot2@tip-bot2>
Date: Wed, 31 Jan 2024 07:21:18 -0000
From: "tip-bot2 for H. Peter Anvin (Intel)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "H. Peter Anvin (Intel)" <hpa@...or.com>, Xin Li <xin3.li@...el.com>,
 Thomas Gleixner <tglx@...utronix.de>, Shan Kang <shan.kang@...el.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/fred] x86/fred: Make exc_page_fault() work for FRED

The following commit has been merged into the x86/fred branch of tip:

Commit-ID:     9f6870bafc183644d20cba702168e37b48e291a7
Gitweb:        https://git.kernel.org/tip/9f6870bafc183644d20cba702168e37b48e291a7
Author:        H. Peter Anvin (Intel) <hpa@...or.com>
AuthorDate:    Tue, 05 Dec 2023 02:50:10 -08:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Tue, 30 Jan 2024 18:20:35 +01:00

x86/fred: Make exc_page_fault() work for FRED

On a FRED system, the faulting address (CR2) is passed on the stack,
to avoid the problem of transient state.  Thus the page fault address
is read from the FRED stack frame instead of CR2 when FRED is enabled.

Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
Signed-off-by: Xin Li <xin3.li@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Shan Kang <shan.kang@...el.com>
Link: https://lore.kernel.org/r/20231205105030.8698-22-xin3.li@intel.com

---
 arch/x86/mm/fault.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 679b09c..fa2d699 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -34,6 +34,7 @@
 #include <asm/kvm_para.h>		/* kvm_handle_async_pf		*/
 #include <asm/vdso.h>			/* fixup_vdso_exception()	*/
 #include <asm/irq_stack.h>
+#include <asm/fred.h>

 #define CREATE_TRACE_POINTS
 #include <asm/trace/exceptions.h>
@@ -1518,8 +1519,10 @@ handle_page_fault(struct pt_regs *regs, unsigned long error_code,

 DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault)
 {
-	unsigned long address = read_cr2();
 	irqentry_state_t state;
+	unsigned long address;
+
+	address = cpu_feature_enabled(X86_FEATURE_FRED) ? fred_event_data(regs) : read_cr2();

 	prefetchw(&current->mm->mmap_lock);