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Message-Id: <20250625151317.f90251f9f893297a3b3345c4@kernel.org>
Date: Wed, 25 Jun 2025 15:13:17 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
x86@...nel.org, Song Liu <songliubraving@...com>, Yonghong Song
<yhs@...com>, John Fastabend <john.fastabend@...il.com>, Hao Luo
<haoluo@...gle.com>, Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
<mhiramat@...nel.org>, Alan Maguire <alan.maguire@...cle.com>, David Laight
<David.Laight@...LAB.COM>, Thomas Weißschuh
<thomas@...ch.de>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCHv3 perf/core 05/22] uprobes: Add nbytes argument to
uprobe_write
On Thu, 5 Jun 2025 15:23:32 +0200
Jiri Olsa <jolsa@...nel.org> wrote:
> 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.
>
Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Thanks,
> Acked-by: Andrii Nakryiko <andrii@...nel.org>
> Acked-by: Oleg Nesterov <oleg@...hat.com>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
> include/linux/uprobes.h | 4 ++--
> kernel/events/uprobes.c | 26 ++++++++++++++------------
> 2 files changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index e13382054435..147c4a0a1af9 100644
> --- 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 777de9b95dd7..f7feb7417a2c 100644
> --- 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
> @@ -489,13 +490,14 @@ 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;
> @@ -505,7 +507,7 @@ 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)))
> @@ -528,7 +530,7 @@ 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;
> @@ -567,7 +569,7 @@ 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);
> }
>
> --
> 2.49.0
>
--
Masami Hiramatsu (Google) <mhiramat@...nel.org>
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