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uprobes: Add nbytes argument to uprobe_write

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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
This commit is contained in:
Jiri Olsa 2025-07-20 13:21:15 +02:00 committed by Peter Zijlstra
parent 33d7b2beaf
commit f8b7c528b4
2 changed files with 16 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/uprobes.h
View File

@ -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);

26
kernel/events/uprobes.c
View File

@ -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 @@ static int __uprobe_write(struct vm_area_struct *vma,
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 @@ int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
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 @@ int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
/* 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);
}