uprobes: Add do_ref_ctr argument to uprobe_write function

Making update_ref_ctr call in uprobe_write conditional based
on do_ref_ctr argument. This way we can use uprobe_write for
instruction update without doing ref_ctr_offset update.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250720112133.244369-8-jolsa@kernel.org

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 518b267564698187561bf2f24cff9f84e93a4643..5080619560d42444b4e85cf287ae6e92b5e322fb 100644 (file)
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -200,7 +200,7 @@ extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
 extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma, unsigned long vaddr, uprobe_opcode_t,
                               bool is_register);
 extern int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma, const unsigned long opcode_vaddr,
-                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify, bool is_register);
+                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify, bool is_register, bool do_update_ref_ctr);
 extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
 extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
 extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc);

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 955e5ed3e383c1958c66c7171ec4fdafe3e35575..da2b3d0deab62746d16e64f755959b8f1801c56d 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -491,12 +491,12 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
                bool is_register)
 {
        return uprobe_write(auprobe, vma, opcode_vaddr, &opcode, UPROBE_SWBP_INSN_SIZE,
-                           verify_opcode, is_register);
+                           verify_opcode, is_register, true /* do_update_ref_ctr */);
 }
 
 int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
                 const unsigned long insn_vaddr, uprobe_opcode_t *insn, int nbytes,
-                uprobe_write_verify_t verify, bool is_register)
+                uprobe_write_verify_t verify, bool is_register, bool do_update_ref_ctr)
 {
        const unsigned long vaddr = insn_vaddr & PAGE_MASK;
        struct mm_struct *mm = vma->vm_mm;
@@ -537,7 +537,7 @@ retry:
        }
 
        /* We are going to replace instruction, update ref_ctr. */
-       if (!ref_ctr_updated && uprobe->ref_ctr_offset) {
+       if (do_update_ref_ctr && !ref_ctr_updated && uprobe->ref_ctr_offset) {
                ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1);
                if (ret) {
                        folio_put(folio);
@@ -589,7 +589,7 @@ retry:
 
 out:
        /* Revert back reference counter if instruction update failed. */
-       if (ret < 0 && ref_ctr_updated)
+       if (do_update_ref_ctr && ret < 0 && ref_ctr_updated)
                update_ref_ctr(uprobe, mm, is_register ? -1 : 1);
 
        /* try collapse pmd for compound page */