Commit dcd8637e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull core x86 updates from Ingo Molnar:

 - x86/alternatives: Drop unnecessary test after call to
   alt_replace_call() (Juergen Gross)

 - x86/dumpstack: Prevent KASAN false positive warnings in
   __show_regs() (Tengda Wu)

* tag 'x86-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/dumpstack: Prevent KASAN false positive warnings in __show_regs()
  x86/alternative: Drop not needed test after call of alt_replace_call()
parents e7d81c1e ced37e9c

arch/x86/kernel/alternative.c

+3 −6
Original line number Diff line number Diff line
@@ -541,7 +541,7 @@ EXPORT_SYMBOL(BUG_func); 
 * Rewrite the "call BUG_func" replacement to point to the target of the

 * indirect pv_ops call "call *disp(%ip)".

 */

static int alt_replace_call(u8 *instr, u8 *insn_buff, struct alt_instr *a)

static unsigned int alt_replace_call(u8 *instr, u8 *insn_buff, struct alt_instr *a)

{

	void *target, *bug = &BUG_func;

	s32 disp;
@@ -625,7 +625,7 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, 
	 * order.

	 */

	for (a = start; a < end; a++) {

		int insn_buff_sz = 0;

		unsigned int insn_buff_sz = 0;



		/*

		 * In case of nested ALTERNATIVE()s the outer alternative might
@@ -665,11 +665,8 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, 
		memcpy(insn_buff, replacement, a->replacementlen);

		insn_buff_sz = a->replacementlen;



		if (a->flags & ALT_FLAG_DIRECT_CALL) {

		if (a->flags & ALT_FLAG_DIRECT_CALL)

			insn_buff_sz = alt_replace_call(instr, insn_buff, a);

			if (insn_buff_sz < 0)

				continue;

		}



		for (; insn_buff_sz < a->instrlen; insn_buff_sz++)

			insn_buff[insn_buff_sz] = 0x90;

arch/x86/kernel/dumpstack.c

+21 −2
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, 
 * in false positive reports. Disable instrumentation to avoid those.

 */

__no_kmsan_checks

static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

static void __show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

				 unsigned long *stack, const char *log_lvl)

{

	struct unwind_state state;
@@ -303,6 +303,25 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, 
	}

}



static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

			       unsigned long *stack, const char *log_lvl)

{

	/*

	 * Disable KASAN to avoid false positives during walking another

	 * task's stacks, as values on these stacks may change concurrently

	 * with task execution.

	 */

	bool disable_kasan = task && task != current;



	if (disable_kasan)

		kasan_disable_current();



	__show_trace_log_lvl(task, regs, stack, log_lvl);



	if (disable_kasan)

		kasan_enable_current();

}



void show_stack(struct task_struct *task, unsigned long *sp,

		       const char *loglvl)

{