[PATCH 0/5] uprobes: transition from kmap_atomic to kmap_local_page

[PATCH 0/5] uprobes: transition from kmap_atomic to kmap_local_page

[Keke Ming]

The use of kmap_atomic/kunmap_atomic is deprecated. The purpose of
kmap-like functions is to create temporary mappings.

kmap_atomic() typically disables preemption, while kmap_local_page()
allows preemption.

According to the documentation, kmap_atomic() is primarily necessary
for contexts that cannot sleep.

> kmap_atomic() may also be used by interrupt contexts, since it does
> not sleep and the callers too may not sleep until after
> kunmap_atomic() is called.

> kunmap_atomic() may implicitly depend on the side effects of atomic
> mappings, i.e. disabling page faults or preemption, or both. In that
> case, explicit calls to pagefault_disable() or preempt_disable() or
> both must be made in conjunction with the use of kmap_local_page().

Link: https://docs.kernel.org/mm/highmem.html#temporary-virtual-mappings
Link: https://lwn.net/Articles/836144/

Keke Ming (5):
  riscv/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
  arm64/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
  mips/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
  arm/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
  uprobes: use kmap_local_page() for temporary page mappings

 arch/arm/probes/uprobes/core.c     |  4 ++--
 arch/arm64/kernel/probes/uprobes.c |  4 ++--
 arch/mips/kernel/uprobes.c         |  4 ++--
 arch/riscv/kernel/probes/uprobes.c |  4 ++--
 kernel/events/uprobes.c            | 12 ++++++------
 5 files changed, 14 insertions(+), 14 deletions(-)

-- 
2.43.0

[PATCH 1/5] riscv/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()

[Keke Ming]

Replace deprecated kmap_atomic() with kmap_local_page().

Signed-off-by: Keke Ming <ming.jvle@gmail.com>
---
 arch/riscv/kernel/probes/uprobes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/probes/uprobes.c b/arch/riscv/kernel/probes/uprobes.c
index cc15f7ca6cc1..f0d0691a8688 100644
--- a/arch/riscv/kernel/probes/uprobes.c
+++ b/arch/riscv/kernel/probes/uprobes.c
@@ -165,7 +165,7 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 			   void *src, unsigned long len)
 {
 	/* Initialize the slot */
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
 	void *dst = kaddr + (vaddr & ~PAGE_MASK);
 	unsigned long start = (unsigned long)dst;
 
@@ -178,5 +178,5 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 	}
 
 	flush_icache_range(start, start + len);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 }
-- 
2.43.0

[PATCH 2/5] arm64/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()

[Keke Ming]

Replace deprecated kmap_atomic() with kmap_local_page().

Signed-off-by: Keke Ming <ming.jvle@gmail.com>
---
 arch/arm64/kernel/probes/uprobes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c
index 941668800aea..4c55bf832ec3 100644
--- a/arch/arm64/kernel/probes/uprobes.c
+++ b/arch/arm64/kernel/probes/uprobes.c
@@ -15,7 +15,7 @@
 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 		void *src, unsigned long len)
 {
-	void *xol_page_kaddr = kmap_atomic(page);
+	void *xol_page_kaddr = kmap_local_page(page);
 	void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);
 
 	/*
@@ -32,7 +32,7 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 	sync_icache_aliases((unsigned long)dst, (unsigned long)dst + len);
 
 done:
-	kunmap_atomic(xol_page_kaddr);
+	kunmap_local(xol_page_kaddr);
 }
 
 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
-- 
2.43.0

[PATCH 3/5] mips/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()

[Keke Ming]

Replace deprecated kmap_atomic() with kmap_local_page().

Signed-off-by: Keke Ming <ming.jvle@gmail.com>
---
 arch/mips/kernel/uprobes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c
index 401b148f8917..05cfc320992b 100644
--- a/arch/mips/kernel/uprobes.c
+++ b/arch/mips/kernel/uprobes.c
@@ -214,11 +214,11 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 	unsigned long kaddr, kstart;
 
 	/* Initialize the slot */
-	kaddr = (unsigned long)kmap_atomic(page);
+	kaddr = (unsigned long)kmap_local_page(page);
 	kstart = kaddr + (vaddr & ~PAGE_MASK);
 	memcpy((void *)kstart, src, len);
 	flush_icache_range(kstart, kstart + len);
-	kunmap_atomic((void *)kaddr);
+	kunmap_local((void *)kaddr);
 }
 
 /**
-- 
2.43.0

[PATCH 4/5] arm/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()

[Keke Ming]

Replace deprecated kmap_atomic() with kmap_local_page().

Signed-off-by: Keke Ming <ming.jvle@gmail.com>
---
 arch/arm/probes/uprobes/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c
index 3d96fb41d624..0e1c6b9e7e54 100644
--- a/arch/arm/probes/uprobes/core.c
+++ b/arch/arm/probes/uprobes/core.c
@@ -113,7 +113,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 			   void *src, unsigned long len)
 {
-	void *xol_page_kaddr = kmap_atomic(page);
+	void *xol_page_kaddr = kmap_local_page(page);
 	void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);
 
 	preempt_disable();
@@ -126,7 +126,7 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 
 	preempt_enable();
 
-	kunmap_atomic(xol_page_kaddr);
+	kunmap_local(xol_page_kaddr);
 }
 
 
-- 
2.43.0

[PATCH 5/5] uprobes: use kmap_local_page() for temporary page mappings

[Keke Ming]

Replace deprecated kmap_atomic() with kmap_local_page().

Signed-off-by: Keke Ming <ming.jvle@gmail.com>
---
 kernel/events/uprobes.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d546d32390a8..a7d7d83ca1d7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -179,16 +179,16 @@ bool __weak is_trap_insn(uprobe_opcode_t *insn)
 
 void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
 {
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
 	memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 }
 
 static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
 {
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
 	memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 }
 
 static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *insn,
@@ -323,7 +323,7 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 		return ret == 0 ? -EBUSY : ret;
 	}
 
-	kaddr = kmap_atomic(page);
+	kaddr = kmap_local_page(page);
 	ptr = kaddr + (vaddr & ~PAGE_MASK);
 
 	if (unlikely(*ptr + d < 0)) {
@@ -336,7 +336,7 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 	*ptr += d;
 	ret = 0;
 out:
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 	put_page(page);
 	return ret;
 }
-- 
2.43.0

Re: [PATCH 0/5] uprobes: transition from kmap_atomic to kmap_local_page

[Oleg Nesterov]

On 01/03, Keke Ming wrote:
>
> Keke Ming (5):
>   riscv/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
>   arm64/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
>   mips/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
>   arm/uprobes: use kmap_local_page() in arch_uprobe_copy_ixol()
>   uprobes: use kmap_local_page() for temporary page mappings
>
>  arch/arm/probes/uprobes/core.c     |  4 ++--
>  arch/arm64/kernel/probes/uprobes.c |  4 ++--
>  arch/mips/kernel/uprobes.c         |  4 ++--
>  arch/riscv/kernel/probes/uprobes.c |  4 ++--
>  kernel/events/uprobes.c            | 12 ++++++------
>  5 files changed, 14 insertions(+), 14 deletions(-)

Thanks,

Acked-by: Oleg Nesterov <oleg@redhat.com>