Handlers for #GP and #SS will now share code to decode the exception
address and retrieve the exception hint string.

The helper, enum, and array should be renamed as they are no longer
specific to #GP.

No functional change intended.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/kernel/traps.c | 62 ++++++++++++++++++++---------------------
 1 file changed, 31 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 5206eb0ab01a..ceb091f17a5b 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -633,28 +633,28 @@ DEFINE_IDTENTRY(exc_bounds)
 	cond_local_irq_disable(regs);
 }
 
-enum kernel_gp_hint {
-	GP_NO_HINT,
-	GP_NON_CANONICAL,
-	GP_CANONICAL,
-	GP_LASS_VIOLATION,
-	GP_NULL_POINTER,
+enum kernel_exc_hint {
+	EXC_NO_HINT,
+	EXC_NON_CANONICAL,
+	EXC_CANONICAL,
+	EXC_LASS_VIOLATION,
+	EXC_NULL_POINTER,
 };
 
-static const char * const kernel_gp_hint_help[] = {
-	[GP_NON_CANONICAL]	= "probably for non-canonical address",
-	[GP_CANONICAL]		= "maybe for address",
-	[GP_LASS_VIOLATION]	= "LASS prevented access to address",
-	[GP_NULL_POINTER]	= "kernel NULL pointer dereference",
+static const char * const kernel_exc_hint_help[] = {
+	[EXC_NON_CANONICAL]	= "probably for non-canonical address",
+	[EXC_CANONICAL]		= "maybe for address",
+	[EXC_LASS_VIOLATION]	= "LASS prevented access to address",
+	[EXC_NULL_POINTER]	= "kernel NULL pointer dereference",
 };
 
 /*
- * When an uncaught #GP occurs, try to determine the memory address accessed by
- * the instruction and return that address to the caller. Also, try to figure
- * out whether any part of the access to that address was non-canonical.
+ * When an uncaught #GP/#SS occurs, try to determine the memory address accessed
+ * by  the instruction and return that address to the caller. Also, try to
+ * figure out whether any part of the access to that address was non-canonical.
  */
-static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
-						 unsigned long *addr)
+static enum kernel_exc_hint get_kernel_exc_address(struct pt_regs *regs,
+						   unsigned long *addr)
 {
 	u8 insn_buf[MAX_INSN_SIZE];
 	struct insn insn;
@@ -662,15 +662,15 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 
 	if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip,
 			MAX_INSN_SIZE))
-		return GP_NO_HINT;
+		return EXC_NO_HINT;
 
 	ret = insn_decode_kernel(&insn, insn_buf);
 	if (ret < 0)
-		return GP_NO_HINT;
+		return EXC_NO_HINT;
 
 	*addr = (unsigned long)insn_get_addr_ref(&insn, regs);
 	if (*addr == -1UL)
-		return GP_NO_HINT;
+		return EXC_NO_HINT;
 
 #ifdef CONFIG_X86_64
 	/*
@@ -680,16 +680,16 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 	 */
 	if (*addr < ~__VIRTUAL_MASK &&
 	    *addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK)
-		return GP_NON_CANONICAL;
+		return EXC_NON_CANONICAL;
 	else if (*addr < ~__VIRTUAL_MASK &&
 		 cpu_feature_enabled(X86_FEATURE_LASS)) {
 		if (*addr < PAGE_SIZE)
-			return GP_NULL_POINTER;
-		return GP_LASS_VIOLATION;
+			return EXC_NULL_POINTER;
+		return EXC_LASS_VIOLATION;
 	}
 #endif
 
-	return GP_CANONICAL;
+	return EXC_CANONICAL;
 }
 
 #define GPFSTR "general protection fault"
@@ -808,8 +808,8 @@ static void gp_user_force_sig_segv(struct pt_regs *regs, int trapnr,
 DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
 {
 	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
-	enum kernel_gp_hint hint = GP_NO_HINT;
-	unsigned long gp_addr;
+	enum kernel_exc_hint hint = EXC_NO_HINT;
+	unsigned long exc_addr;
 
 	if (user_mode(regs) && try_fixup_enqcmd_gp())
 		return;
@@ -846,21 +846,21 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
 	if (error_code)
 		snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
 	else
-		hint = get_kernel_gp_address(regs, &gp_addr);
+		hint = get_kernel_exc_address(regs, &exc_addr);
 
-	if (hint != GP_NO_HINT) {
+	if (hint != EXC_NO_HINT) {
 		snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
-			 kernel_gp_hint_help[hint], gp_addr);
+			 kernel_exc_hint_help[hint], exc_addr);
 	}
 
 	/*
 	 * KASAN is interested only in the non-canonical case, clear it
 	 * otherwise.
 	 */
-	if (hint != GP_NON_CANONICAL)
-		gp_addr = 0;
+	if (hint != EXC_NON_CANONICAL)
+		exc_addr = 0;
 
-	die_addr(desc, regs, error_code, gp_addr);
+	die_addr(desc, regs, error_code, exc_addr);
 
 exit:
 	cond_local_irq_disable(regs);
-- 
2.47.2

On 7/1/2025 2:58 AM, Kirill A. Shutemov wrote:
> Handlers for #GP and #SS will now share code to decode the exception
> address and retrieve the exception hint string.
> 

This is missing an essential "why"? Why do #GP and #SS handlers need to
share code? None of the patches prior to this have hinted this.

It can probably be deduced from a later patch, but it needs to be
clarified in this one. Maybe a simplified version of the text from the SDM:

"In most cases, an access causing a LASS violation results in a general
protection exception (#GP); for stack accesses (those due to
stack-oriented instructions, as well as accesses that implicitly or
explicitly use the SS segment register), a stack fault (#SS) is generated."

> The helper, enum, and array should be renamed as they are no longer
> specific to #GP.
> 
> No functional change intended.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
>  arch/x86/kernel/traps.c | 62 ++++++++++++++++++++---------------------
>  1 file changed, 31 insertions(+), 31 deletions(-)
> 

The code changes look okay to me except a minor nit below.

>  #define GPFSTR "general protection fault"
> @@ -808,8 +808,8 @@ static void gp_user_force_sig_segv(struct pt_regs *regs, int trapnr,
>  DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
>  {
>  	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
> -	enum kernel_gp_hint hint = GP_NO_HINT;
> -	unsigned long gp_addr;

gp_addr is a local variable to the #GP handler. It can probably stay the
same.

> +	enum kernel_exc_hint hint = EXC_NO_HINT;
> +	unsigned long exc_addr;
>  
>  	if (user_mode(regs) && try_fixup_enqcmd_gp())
>  		return;
> @@ -846,21 +846,21 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
>  	if (error_code)
>  		snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
>  	else
> -		hint = get_kernel_gp_address(regs, &gp_addr);
> +		hint = get_kernel_exc_address(regs, &exc_addr);
>  
> -	if (hint != GP_NO_HINT) {
> +	if (hint != EXC_NO_HINT) {
>  		snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
> -			 kernel_gp_hint_help[hint], gp_addr);
> +			 kernel_exc_hint_help[hint], exc_addr);
>  	}
>  
>  	/*
>  	 * KASAN is interested only in the non-canonical case, clear it
>  	 * otherwise.
>  	 */
> -	if (hint != GP_NON_CANONICAL)
> -		gp_addr = 0;
> +	if (hint != EXC_NON_CANONICAL)
> +		exc_addr = 0;
>  
> -	die_addr(desc, regs, error_code, gp_addr);
> +	die_addr(desc, regs, error_code, exc_addr);
>  
>  exit:
>  	cond_local_irq_disable(regs);