This is a note to let you know that I've just added the patch titled
x86/ptrace: Add FRED additional information to the pt_regs structure
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-ptrace-add-fred-additional-information-to-the-pt.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f91e62282bab1b2f055166147b0b2323c710f23b
Author: Xin Li <xin3.li@xxxxxxxxx>
Date: Tue Dec 5 02:50:03 2023 -0800
x86/ptrace: Add FRED additional information to the pt_regs structure
[ Upstream commit 3c77bf02d0c03beb3efdf7a5b427fb2e1a76c265 ]
FRED defines additional information in the upper 48 bits of cs/ss
fields. Therefore add the information definitions into the pt_regs
structure.
Specifically introduce a new structure fred_ss to denote the FRED flags
above SS selector, which avoids FRED_SSX_ macros and makes the code
simpler and easier to read.
Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Originally-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231205105030.8698-15-xin3.li@xxxxxxxxx
Stable-dep-of: dc81e556f2a0 ("x86/fred: Clear WFE in missing-ENDBRANCH #CPs")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index b268cd2a2d01..5a83fbd9bc0b 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -56,6 +56,50 @@ struct pt_regs {
#else /* __i386__ */
+struct fred_cs {
+ /* CS selector */
+ u64 cs : 16,
+ /* Stack level at event time */
+ sl : 2,
+ /* IBT in WAIT_FOR_ENDBRANCH state */
+ wfe : 1,
+ : 45;
+};
+
+struct fred_ss {
+ /* SS selector */
+ u64 ss : 16,
+ /* STI state */
+ sti : 1,
+ /* Set if syscall, sysenter or INT n */
+ swevent : 1,
+ /* Event is NMI type */
+ nmi : 1,
+ : 13,
+ /* Event vector */
+ vector : 8,
+ : 8,
+ /* Event type */
+ type : 4,
+ : 4,
+ /* Event was incident to enclave execution */
+ enclave : 1,
+ /* CPU was in long mode */
+ lm : 1,
+ /*
+ * Nested exception during FRED delivery, not set
+ * for #DF.
+ */
+ nested : 1,
+ : 1,
+ /*
+ * The length of the instruction causing the event.
+ * Only set for INTO, INT1, INT3, INT n, SYSCALL
+ * and SYSENTER. 0 otherwise.
+ */
+ insnlen : 4;
+};
+
struct pt_regs {
/*
* C ABI says these regs are callee-preserved. They aren't saved on
@@ -85,6 +129,12 @@ struct pt_regs {
* - the syscall number (syscall, sysenter, int80)
* - error_code stored by the CPU on traps and exceptions
* - the interrupt number for device interrupts
+ *
+ * A FRED stack frame starts here:
+ * 1) It _always_ includes an error code;
+ *
+ * 2) The return frame for ERET[US] starts here, but
+ * the content of orig_ax is ignored.
*/
unsigned long orig_ax;
@@ -92,24 +142,30 @@ struct pt_regs {
unsigned long ip;
union {
- /* The full 64-bit data slot containing CS */
- u64 csx;
/* CS selector */
u16 cs;
+ /* The extended 64-bit data slot containing CS */
+ u64 csx;
+ /* The FRED CS extension */
+ struct fred_cs fred_cs;
};
unsigned long flags;
unsigned long sp;
union {
- /* The full 64-bit data slot containing SS */
- u64 ssx;
/* SS selector */
u16 ss;
+ /* The extended 64-bit data slot containing SS */
+ u64 ssx;
+ /* The FRED SS extension */
+ struct fred_ss fred_ss;
};
/*
- * Top of stack on IDT systems.
+ * Top of stack on IDT systems, while FRED systems have extra fields
+ * defined above for storing exception related information, e.g. CR2 or
+ * DR6.
*/
};
