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Core x86 changes for v6.19: 

- 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)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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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()
This commit is contained in:
Linus Torvalds 2025-12-01 21:31:02 -08:00
parent e7d81c1ed6 ced37e9cea
commit dcd8637edb
2 changed files with 24 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/kernel/alternative.c
View File

@ -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;

23
arch/x86/kernel/dumpstack.c
View File

@ -181,8 +181,8 @@ 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,
unsigned long *stack, const char *log_lvl)
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;
struct stack_info stack_info = {0};
@ -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)
{