uprobes: Add is_register argument to uprobe_write and uprobe_write_opcode

The uprobe_write has special path to restore the original page when we
write original instruction back. This happens when uprobe_write detects
that we want to write anything else but breakpoint instruction.

Moving the detection away and passing it to uprobe_write as argument,
so it's possible to write different instructions (other than just
breakpoint and rest).

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-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/20250720112133.244369-7-jolsa@kernel.org

diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c
index 885e0c5e8c20dfd70f67b82ff8523bb128454715..3d96fb41d6245d22223d2a27b92306fe52535463 100644 (file)
--- a/arch/arm/probes/uprobes/core.c
+++ b/arch/arm/probes/uprobes/core.c
@@ -30,7 +30,7 @@ int set_swbp(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
             unsigned long vaddr)
 {
        return uprobe_write_opcode(auprobe, vma, vaddr,
-                  __opcode_to_mem_arm(auprobe->bpinsn));
+                  __opcode_to_mem_arm(auprobe->bpinsn), true);
 }
 
 bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 147c4a0a1af9f34fca4353c6d003099e2203e950..518b267564698187561bf2f24cff9f84e93a4643 100644 (file)
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -197,9 +197,10 @@ extern bool is_swbp_insn(uprobe_opcode_t *insn);
 extern bool is_trap_insn(uprobe_opcode_t *insn);
 extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
 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);
+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);
+                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify, bool is_register);
 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 c133fd4b492d83153ea823f6efd3e33c9dfb86e6..955e5ed3e383c1958c66c7171ec4fdafe3e35575 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -402,10 +402,10 @@ static bool orig_page_is_identical(struct vm_area_struct *vma,
 
 static int __uprobe_write(struct vm_area_struct *vma,
                struct folio_walk *fw, struct folio *folio,
-               unsigned long insn_vaddr, uprobe_opcode_t *insn, int nbytes)
+               unsigned long insn_vaddr, uprobe_opcode_t *insn, int nbytes,
+               bool is_register)
 {
        const unsigned long vaddr = insn_vaddr & PAGE_MASK;
-       const bool is_register = !!is_swbp_insn(insn);
        bool pmd_mappable;
 
        /* For now, we'll only handle PTE-mapped folios. */
@@ -487,26 +487,27 @@ remap:
  * Return 0 (success) or a negative errno.
  */
 int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
-               const unsigned long opcode_vaddr, uprobe_opcode_t opcode)
+               const unsigned long opcode_vaddr, uprobe_opcode_t opcode,
+               bool is_register)
 {
-       return uprobe_write(auprobe, vma, opcode_vaddr, &opcode, UPROBE_SWBP_INSN_SIZE, verify_opcode);
+       return uprobe_write(auprobe, vma, opcode_vaddr, &opcode, UPROBE_SWBP_INSN_SIZE,
+                           verify_opcode, is_register);
 }
 
 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)
+                uprobe_write_verify_t verify, bool is_register)
 {
        const unsigned long vaddr = insn_vaddr & PAGE_MASK;
        struct mm_struct *mm = vma->vm_mm;
        struct uprobe *uprobe;
-       int ret, is_register, ref_ctr_updated = 0;
+       int ret, ref_ctr_updated = 0;
        unsigned int gup_flags = FOLL_FORCE;
        struct mmu_notifier_range range;
        struct folio_walk fw;
        struct folio *folio;
        struct page *page;
 
-       is_register = is_swbp_insn(insn);
        uprobe = container_of(auprobe, struct uprobe, arch);
 
        if (WARN_ON_ONCE(!is_cow_mapping(vma->vm_flags)))
@@ -568,7 +569,7 @@ retry:
        /* Walk the page tables again, to perform the actual update. */
        if (folio_walk_start(&fw, vma, vaddr, 0)) {
                if (fw.page == page)
-                       ret = __uprobe_write(vma, &fw, folio, insn_vaddr, insn, nbytes);
+                       ret = __uprobe_write(vma, &fw, folio, insn_vaddr, insn, nbytes, is_register);
                folio_walk_end(&fw, vma);
        }
 
@@ -610,7 +611,7 @@ out:
 int __weak set_swbp(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
                unsigned long vaddr)
 {
-       return uprobe_write_opcode(auprobe, vma, vaddr, UPROBE_SWBP_INSN);
+       return uprobe_write_opcode(auprobe, vma, vaddr, UPROBE_SWBP_INSN, true);
 }
 
 /**
@@ -626,7 +627,7 @@ int __weak set_orig_insn(struct arch_uprobe *auprobe,
                struct vm_area_struct *vma, unsigned long vaddr)
 {
        return uprobe_write_opcode(auprobe, vma, vaddr,
-                       *(uprobe_opcode_t *)&auprobe->insn);
+                       *(uprobe_opcode_t *)&auprobe->insn, false);
 }
 
 /* uprobe should have guaranteed positive refcount */