[PATCH v13 21/35] x86/fred: Make exc_page_fault() work for FRED

Xin Li
2023-12-05T11:21:29Z

From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

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@zytor.com>
Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
---

Change since v12:
* No "we" in a commit message, use passive voice (Borislav Petkov).
---
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 ab778eac1952..7675bc067153 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>
@@ -1516,8 +1517,10 @@ 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);

--
2.43.0