[PATCHv6 perf/core 06/22] uprobes: Add is_register argument to uprobe_write and uprobe_write_opcode

[Jiri Olsa <jolsa@kernel.org>]

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).

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/arm/probes/uprobes/core.c |  2 +-
 include/linux/uprobes.h        |  5 +++--
 kernel/events/uprobes.c        | 21 +++++++++++----------
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c
index 885e0c5e8c20..3d96fb41d624 100644
--- 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 147c4a0a1af9..518b26756469 100644
--- 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 f7feb7417a2c..1e5dc3b30707 100644
--- 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. */
@@ -488,26 +488,27 @@ static int __uprobe_write(struct vm_area_struct *vma,
  * 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)))
@@ -569,7 +570,7 @@ 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, insn_vaddr, insn, nbytes);
+			ret = __uprobe_write(vma, &fw, folio, insn_vaddr, insn, nbytes, is_register);
 		folio_walk_end(&fw, vma);
 	}
 
@@ -611,7 +612,7 @@ int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
 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);
 }
 
 /**
@@ -627,7 +628,7 @@ 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 */
-- 
2.50.1