uprobes: Add nbytes argument to uprobe_write

Adding nbytes argument to uprobe_write and related functions as
preparation for writing whole instructions in following changes.

Also renaming opcode arguments to insn, which seems to fit better.

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/20250720112133.244369-6-jolsa@kernel.org

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index e13382054435d8664e8a83cccf26eaa2cfbec96a..147c4a0a1af9f34fca4353c6d003099e2203e950 100644 (file)
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -188,7 +188,7 @@ struct uprobes_state {
 };
 
 typedef int (*uprobe_write_verify_t)(struct page *page, unsigned long vaddr,
-                                    uprobe_opcode_t *opcode);
+                                    uprobe_opcode_t *insn, int nbytes);
 
 extern void __init uprobes_init(void);
 extern int set_swbp(struct arch_uprobe *aup, struct vm_area_struct *vma, unsigned long vaddr);
@@ -199,7 +199,7 @@ 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(struct arch_uprobe *auprobe, struct vm_area_struct *vma, const unsigned long opcode_vaddr,
-                       uprobe_opcode_t opcode, uprobe_write_verify_t verify);
+                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify);
 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 838ac40e91e616c8110c5a57cdbc18437f375261..c133fd4b492d83153ea823f6efd3e33c9dfb86e6 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -191,7 +191,8 @@ static void copy_to_page(struct page *page, unsigned long vaddr, const void *src
        kunmap_atomic(kaddr);
 }
 
-static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
+static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *insn,
+                        int nbytes)
 {
        uprobe_opcode_t old_opcode;
        bool is_swbp;
@@ -208,7 +209,7 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t
        uprobe_copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
        is_swbp = is_swbp_insn(&old_opcode);
 
-       if (is_swbp_insn(new_opcode)) {
+       if (is_swbp_insn(insn)) {
                if (is_swbp)            /* register: already installed? */
                        return 0;
        } else {
@@ -401,10 +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 opcode_vaddr, uprobe_opcode_t opcode)
+               unsigned long insn_vaddr, uprobe_opcode_t *insn, int nbytes)
 {
-       const unsigned long vaddr = opcode_vaddr & PAGE_MASK;
-       const bool is_register = !!is_swbp_insn(&opcode);
+       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. */
@@ -429,7 +430,7 @@ static int __uprobe_write(struct vm_area_struct *vma,
         */
        flush_cache_page(vma, vaddr, pte_pfn(fw->pte));
        fw->pte = ptep_clear_flush(vma, vaddr, fw->ptep);
-       copy_to_page(fw->page, opcode_vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
+       copy_to_page(fw->page, insn_vaddr, insn, nbytes);
 
        /*
         * When unregistering, we may only zap a PTE if uffd is disabled and
@@ -488,13 +489,14 @@ remap:
 int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
                const unsigned long opcode_vaddr, uprobe_opcode_t opcode)
 {
-       return uprobe_write(auprobe, vma, opcode_vaddr, opcode, verify_opcode);
+       return uprobe_write(auprobe, vma, opcode_vaddr, &opcode, UPROBE_SWBP_INSN_SIZE, verify_opcode);
 }
 
 int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
-                const unsigned long opcode_vaddr, uprobe_opcode_t opcode, uprobe_write_verify_t verify)
+                const unsigned long insn_vaddr, uprobe_opcode_t *insn, int nbytes,
+                uprobe_write_verify_t verify)
 {
-       const unsigned long vaddr = opcode_vaddr & PAGE_MASK;
+       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;
@@ -504,7 +506,7 @@ int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
        struct folio *folio;
        struct page *page;
 
-       is_register = is_swbp_insn(&opcode);
+       is_register = is_swbp_insn(insn);
        uprobe = container_of(auprobe, struct uprobe, arch);
 
        if (WARN_ON_ONCE(!is_cow_mapping(vma->vm_flags)))
@@ -527,7 +529,7 @@ retry:
                goto out;
        folio = page_folio(page);
 
-       ret = verify(page, opcode_vaddr, &opcode);
+       ret = verify(page, insn_vaddr, insn, nbytes);
        if (ret <= 0) {
                folio_put(folio);
                goto out;
@@ -566,7 +568,7 @@ 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, opcode_vaddr, opcode);
+                       ret = __uprobe_write(vma, &fw, folio, insn_vaddr, insn, nbytes);
                folio_walk_end(&fw, vma);
        }