[PATCH v2 0/7] sections: Unify kernel sections range check and use

[PATCH v2 0/7] sections: Unify kernel sections range check and use

[Kefeng Wang]

There are three head files(kallsyms.h, kernel.h and sections.h) which
include the kernel sections range check, let's make some cleanup and
unify them.

1. cleanup arch specific text/data check and fix address boundary check
   in kallsyms.h
2. make all the basic/core kernel range check function into sections.h
3. update all the callers, and use the helper in sections.h to simplify
   the code

After this series, we have 5 APIs about kernel sections range check in
sections.h

 * is_kernel_core_data()	--- come from core_kernel_data() in kernel.h
 * is_kernel_rodata()		--- already in sections.h
 * is_kernel_text()		--- come from kallsyms.h
 * is_kernel_inittext()		--- come from kernel.h and kallsyms.h
 * is_kernel()			--- come from kallsyms.h


Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-arch@vger.kernel.org 
Cc: iommu@lists.linux-foundation.org
Cc: bpf@vger.kernel.org 

v2:
- add ACK/RW to patch2, and drop inappropriate fix tag
- keep 'core' to check kernel data, suggestted by Steven Rostedt
  <rostedt@goodmis.org>, rename is_kernel_data() to is_kernel_core_data()
- drop patch8 which is merged
- drop patch9 which is resend independently

v1:
https://lore.kernel.org/linux-arch/20210626073439.150586-1-wangkefeng.wang@huawei.com

Kefeng Wang (7):
  kallsyms: Remove arch specific text and data check
  kallsyms: Fix address-checks for kernel related range
  sections: Move and rename core_kernel_data() to is_kernel_core_data()
  sections: Move is_kernel_inittext() into sections.h
  kallsyms: Rename is_kernel() and is_kernel_text()
  sections: Add new is_kernel() and is_kernel_text()
  powerpc/mm: Use is_kernel_text() and is_kernel_inittext() helper

 arch/powerpc/mm/pgtable_32.c   |  7 +---
 arch/x86/kernel/unwind_orc.c   |  2 +-
 arch/x86/net/bpf_jit_comp.c    |  2 +-
 include/asm-generic/sections.h | 71 ++++++++++++++++++++++++++--------
 include/linux/kallsyms.h       | 21 +++-------
 include/linux/kernel.h         |  2 -
 kernel/cfi.c                   |  2 +-
 kernel/extable.c               | 33 ++--------------
 kernel/locking/lockdep.c       |  3 --
 kernel/trace/ftrace.c          |  2 +-
 mm/kasan/report.c              |  2 +-
 net/sysctl_net.c               |  2 +-
 12 files changed, 72 insertions(+), 77 deletions(-)

-- 
2.26.2

[PATCH v2 1/7] kallsyms: Remove arch specific text and data check

[Kefeng Wang]

After commit 4ba66a976072 ("arch: remove blackfin port"),
no need arch-specific text/data check.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/asm-generic/sections.h | 16 ----------------
 include/linux/kallsyms.h       |  3 +--
 kernel/locking/lockdep.c       |  3 ---
 3 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index d16302d3eb59..817309e289db 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -64,22 +64,6 @@ extern __visible const void __nosave_begin, __nosave_end;
 #define dereference_kernel_function_descriptor(p) ((void *)(p))
 #endif
 
-/* random extra sections (if any).  Override
- * in asm/sections.h */
-#ifndef arch_is_kernel_text
-static inline int arch_is_kernel_text(unsigned long addr)
-{
-	return 0;
-}
-#endif
-
-#ifndef arch_is_kernel_data
-static inline int arch_is_kernel_data(unsigned long addr)
-{
-	return 0;
-}
-#endif
-
 /*
  * Check if an address is part of freed initmem. This is needed on architectures
  * with virt == phys kernel mapping, for code that wants to check if an address
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 6851c2313cad..2a241e3f063f 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -34,8 +34,7 @@ static inline int is_kernel_inittext(unsigned long addr)
 
 static inline int is_kernel_text(unsigned long addr)
 {
-	if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
-	    arch_is_kernel_text(addr))
+	if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index bf1c00c881e4..64b17e995108 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -803,9 +803,6 @@ static int static_obj(const void *obj)
 	if ((addr >= start) && (addr < end))
 		return 1;
 
-	if (arch_is_kernel_data(addr))
-		return 1;
-
 	/*
 	 * in-kernel percpu var?
 	 */
-- 
2.26.2

[PATCH v2 2/7] kallsyms: Fix address-checks for kernel related range

[Kefeng Wang]

The is_kernel_inittext/is_kernel_text/is_kernel function should not
include the end address(the labels _einittext, _etext and _end) when
check the address range, the issue exists since Linux v2.6.12.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/kallsyms.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 2a241e3f063f..b016c62f30a6 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -27,21 +27,21 @@ struct module;
 static inline int is_kernel_inittext(unsigned long addr)
 {
 	if (addr >= (unsigned long)_sinittext
-	    && addr <= (unsigned long)_einittext)
+	    && addr < (unsigned long)_einittext)
 		return 1;
 	return 0;
 }
 
 static inline int is_kernel_text(unsigned long addr)
 {
-	if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext))
+	if ((addr >= (unsigned long)_stext && addr < (unsigned long)_etext))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
 
 static inline int is_kernel(unsigned long addr)
 {
-	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
+	if (addr >= (unsigned long)_stext && addr < (unsigned long)_end)
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
-- 
2.26.2

Re: [PATCH v2 2/7] kallsyms: Fix address-checks for kernel related range

[Steven Rostedt]

On Wed, 28 Jul 2021 16:13:15 +0800
Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> The is_kernel_inittext/is_kernel_text/is_kernel function should not
> include the end address(the labels _einittext, _etext and _end) when
> check the address range, the issue exists since Linux v2.6.12.
> 
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> ---
>  include/linux/kallsyms.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
> index 2a241e3f063f..b016c62f30a6 100644
> --- a/include/linux/kallsyms.h
> +++ b/include/linux/kallsyms.h
> @@ -27,21 +27,21 @@ struct module;
>  static inline int is_kernel_inittext(unsigned long addr)
>  {
>  	if (addr >= (unsigned long)_sinittext
> -	    && addr <= (unsigned long)_einittext)
> +	    && addr < (unsigned long)_einittext)
>  		return 1;
>  	return 0;
>  }
>  
>  static inline int is_kernel_text(unsigned long addr)
>  {
> -	if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext))
> +	if ((addr >= (unsigned long)_stext && addr < (unsigned long)_etext))
>  		return 1;
>  	return in_gate_area_no_mm(addr);
>  }
>  
>  static inline int is_kernel(unsigned long addr)
>  {
> -	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
> +	if (addr >= (unsigned long)_stext && addr < (unsigned long)_end)
>  		return 1;
>  	return in_gate_area_no_mm(addr);
>  }

Re: [PATCH v2 2/7] kallsyms: Fix address-checks for kernel related range

[Kefeng Wang]

On 2021/7/28 22:46, Steven Rostedt wrote:
> On Wed, 28 Jul 2021 16:13:15 +0800
> Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>> The is_kernel_inittext/is_kernel_text/is_kernel function should not
>> include the end address(the labels _einittext, _etext and _end) when
>> check the address range, the issue exists since Linux v2.6.12.
>>
>> Cc: Arnd Bergmann <arnd@arndb.de>
>> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
>> Cc: Petr Mladek <pmladek@suse.com>
>> Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
>> Reviewed-by: Petr Mladek <pmladek@suse.com>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Thanks.

>
> -- Steve
>

[PATCH v2 3/7] sections: Move and rename core_kernel_data() to is_kernel_core_data()

[Kefeng Wang]

Move core_kernel_data() into sections.h and rename it to
is_kernel_core_data(), also make it return bool value, then
update all the callers.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/asm-generic/sections.h | 14 ++++++++++++++
 include/linux/kernel.h         |  1 -
 kernel/extable.c               | 18 ------------------
 kernel/trace/ftrace.c          |  2 +-
 net/sysctl_net.c               |  2 +-
 5 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 817309e289db..26ed9fc9b4e3 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -142,6 +142,20 @@ static inline bool init_section_intersects(void *virt, size_t size)
 	return memory_intersects(__init_begin, __init_end, virt, size);
 }
 
+/**
+ * is_kernel_core_data - checks if the pointer address is located in the
+ *			 .data section
+ *
+ * @addr: address to check
+ *
+ * Returns: true if the address is located in .data, false otherwise.
+ */
+static inline bool is_kernel_core_data(unsigned long addr)
+{
+	return addr >= (unsigned long)_sdata &&
+	       addr < (unsigned long)_edata;
+}
+
 /**
  * is_kernel_rodata - checks if the pointer address is located in the
  *                    .rodata section
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 1b2f0a7e00d6..0622418bafbc 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -230,7 +230,6 @@ extern char *next_arg(char *args, char **param, char **val);
 
 extern int core_kernel_text(unsigned long addr);
 extern int init_kernel_text(unsigned long addr);
-extern int core_kernel_data(unsigned long addr);
 extern int __kernel_text_address(unsigned long addr);
 extern int kernel_text_address(unsigned long addr);
 extern int func_ptr_is_kernel_text(void *ptr);
diff --git a/kernel/extable.c b/kernel/extable.c
index b0ea5eb0c3b4..da26203841d4 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -82,24 +82,6 @@ int notrace core_kernel_text(unsigned long addr)
 	return 0;
 }
 
-/**
- * core_kernel_data - tell if addr points to kernel data
- * @addr: address to test
- *
- * Returns true if @addr passed in is from the core kernel data
- * section.
- *
- * Note: On some archs it may return true for core RODATA, and false
- *  for others. But will always be true for core RW data.
- */
-int core_kernel_data(unsigned long addr)
-{
-	if (addr >= (unsigned long)_sdata &&
-	    addr < (unsigned long)_edata)
-		return 1;
-	return 0;
-}
-
 int __kernel_text_address(unsigned long addr)
 {
 	if (kernel_text_address(addr))
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index e6fb3e6e1ffc..d01ca1cb2d5f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -323,7 +323,7 @@ int __register_ftrace_function(struct ftrace_ops *ops)
 	if (!ftrace_enabled && (ops->flags & FTRACE_OPS_FL_PERMANENT))
 		return -EBUSY;
 
-	if (!core_kernel_data((unsigned long)ops))
+	if (!is_kernel_core_data((unsigned long)ops))
 		ops->flags |= FTRACE_OPS_FL_DYNAMIC;
 
 	add_ftrace_ops(&ftrace_ops_list, ops);
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index f6cb0d4d114c..4b45ed631eb8 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -144,7 +144,7 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,
 		addr = (unsigned long)ent->data;
 		if (is_module_address(addr))
 			where = "module";
-		else if (core_kernel_data(addr))
+		else if (is_kernel_core_data(addr))
 			where = "kernel";
 		else
 			continue;
-- 
2.26.2

[PATCH v2 4/7] sections: Move is_kernel_inittext() into sections.h

[Kefeng Wang]

The is_kernel_inittext() and init_kernel_text() are with same
functionality, let's just keep is_kernel_inittext() and move
it into sections.h, then update all the callers.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: x86@kernel.org
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/x86/kernel/unwind_orc.c   |  2 +-
 include/asm-generic/sections.h | 14 ++++++++++++++
 include/linux/kallsyms.h       |  8 --------
 include/linux/kernel.h         |  1 -
 kernel/extable.c               | 12 ++----------
 5 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index a1202536fc57..d92ec2ced059 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -175,7 +175,7 @@ static struct orc_entry *orc_find(unsigned long ip)
 	}
 
 	/* vmlinux .init slow lookup: */
-	if (init_kernel_text(ip))
+	if (is_kernel_inittext(ip))
 		return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
 				  __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
 
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 26ed9fc9b4e3..4f2f32aa2b7a 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -170,4 +170,18 @@ static inline bool is_kernel_rodata(unsigned long addr)
 	       addr < (unsigned long)__end_rodata;
 }
 
+/**
+ * is_kernel_inittext - checks if the pointer address is located in the
+ *                    .init.text section
+ *
+ * @addr: address to check
+ *
+ * Returns: true if the address is located in .init.text, false otherwise.
+ */
+static inline bool is_kernel_inittext(unsigned long addr)
+{
+	return addr >= (unsigned long)_sinittext &&
+	       addr < (unsigned long)_einittext;
+}
+
 #endif /* _ASM_GENERIC_SECTIONS_H_ */
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index b016c62f30a6..8a9d329c927c 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -24,14 +24,6 @@
 struct cred;
 struct module;
 
-static inline int is_kernel_inittext(unsigned long addr)
-{
-	if (addr >= (unsigned long)_sinittext
-	    && addr < (unsigned long)_einittext)
-		return 1;
-	return 0;
-}
-
 static inline int is_kernel_text(unsigned long addr)
 {
 	if ((addr >= (unsigned long)_stext && addr < (unsigned long)_etext))
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 0622418bafbc..d4ba46cf4737 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -229,7 +229,6 @@ extern bool parse_option_str(const char *str, const char *option);
 extern char *next_arg(char *args, char **param, char **val);
 
 extern int core_kernel_text(unsigned long addr);
-extern int init_kernel_text(unsigned long addr);
 extern int __kernel_text_address(unsigned long addr);
 extern int kernel_text_address(unsigned long addr);
 extern int func_ptr_is_kernel_text(void *ptr);
diff --git a/kernel/extable.c b/kernel/extable.c
index da26203841d4..98ca627ac5ef 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -62,14 +62,6 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 	return e;
 }
 
-int init_kernel_text(unsigned long addr)
-{
-	if (addr >= (unsigned long)_sinittext &&
-	    addr < (unsigned long)_einittext)
-		return 1;
-	return 0;
-}
-
 int notrace core_kernel_text(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext &&
@@ -77,7 +69,7 @@ int notrace core_kernel_text(unsigned long addr)
 		return 1;
 
 	if (system_state < SYSTEM_RUNNING &&
-	    init_kernel_text(addr))
+	    is_kernel_inittext(addr))
 		return 1;
 	return 0;
 }
@@ -94,7 +86,7 @@ int __kernel_text_address(unsigned long addr)
 	 * Since we are after the module-symbols check, there's
 	 * no danger of address overlap:
 	 */
-	if (init_kernel_text(addr))
+	if (is_kernel_inittext(addr))
 		return 1;
 	return 0;
 }
-- 
2.26.2

[PATCH v2 5/7] kallsyms: Rename is_kernel() and is_kernel_text()

[Kefeng Wang]

The is_kernel[_text]() function check the address whether or not
in kernel[_text] ranges, also they will check the address whether
or not in gate area, so use better name.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: bpf@vger.kernel.org
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/x86/net/bpf_jit_comp.c | 2 +-
 include/linux/kallsyms.h    | 8 ++++----
 kernel/cfi.c                | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 333650b9372a..c87d0dd4370d 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -372,7 +372,7 @@ static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 		       void *old_addr, void *new_addr)
 {
-	if (!is_kernel_text((long)ip) &&
+	if (!is_kernel_text_or_gate_area((long)ip) &&
 	    !is_bpf_text_address((long)ip))
 		/* BPF poking in modules is not supported */
 		return -EINVAL;
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 8a9d329c927c..4f501ac9c2c2 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -24,14 +24,14 @@
 struct cred;
 struct module;
 
-static inline int is_kernel_text(unsigned long addr)
+static inline int is_kernel_text_or_gate_area(unsigned long addr)
 {
 	if ((addr >= (unsigned long)_stext && addr < (unsigned long)_etext))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
 
-static inline int is_kernel(unsigned long addr)
+static inline int is_kernel_or_gate_area(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext && addr < (unsigned long)_end)
 		return 1;
@@ -41,9 +41,9 @@ static inline int is_kernel(unsigned long addr)
 static inline int is_ksym_addr(unsigned long addr)
 {
 	if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
-		return is_kernel(addr);
+		return is_kernel_or_gate_area(addr);
 
-	return is_kernel_text(addr) || is_kernel_inittext(addr);
+	return is_kernel_text_or_gate_area(addr) || is_kernel_inittext(addr);
 }
 
 static inline void *dereference_symbol_descriptor(void *ptr)
diff --git a/kernel/cfi.c b/kernel/cfi.c
index e17a56639766..e7d90eff4382 100644
--- a/kernel/cfi.c
+++ b/kernel/cfi.c
@@ -282,7 +282,7 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr)
 {
 	cfi_check_fn fn = NULL;
 
-	if (is_kernel_text(ptr))
+	if (is_kernel_text_or_gate_area(ptr))
 		return __cfi_check;
 
 	/*
-- 
2.26.2

Re: [PATCH v2 5/7] kallsyms: Rename is_kernel() and is_kernel_text()

[Steven Rostedt]

On Wed, 28 Jul 2021 16:13:18 +0800
Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> The is_kernel[_text]() function check the address whether or not
> in kernel[_text] ranges, also they will check the address whether
> or not in gate area, so use better name.

Do you know what a gate area is?

Because I believe gate area is kernel text, so the rename just makes it
redundant and more confusing.

-- Steve

Re: [PATCH v2 5/7] kallsyms: Rename is_kernel() and is_kernel_text()

[Kefeng Wang]

On 2021/7/28 23:28, Steven Rostedt wrote:
> On Wed, 28 Jul 2021 16:13:18 +0800
> Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>> The is_kernel[_text]() function check the address whether or not
>> in kernel[_text] ranges, also they will check the address whether
>> or not in gate area, so use better name.
> Do you know what a gate area is?
>
> Because I believe gate area is kernel text, so the rename just makes it
> redundant and more confusing.

Yes, the gate area(eg, vectors part on ARM32, similar on x86/ia64) is 
kernel text.

I want to keep the 'basic' section boundaries check, which only check 
the start/end

of sections, all in section.h,  could we use 'generic' or 'basic' or 
'core' in the naming?

  * is_kernel_generic_data()	--- come from core_kernel_data() in kernel.h
  * is_kernel_generic_text()

The old helper could remain unchanged, any suggestion, thanks.

>
> -- Steve
> .
>

Re: [PATCH v2 5/7] kallsyms: Rename is_kernel() and is_kernel_text()

[Steven Rostedt]

On Thu, 29 Jul 2021 10:00:51 +0800
Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> On 2021/7/28 23:28, Steven Rostedt wrote:
> > On Wed, 28 Jul 2021 16:13:18 +0800
> > Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
> >  
> >> The is_kernel[_text]() function check the address whether or not
> >> in kernel[_text] ranges, also they will check the address whether
> >> or not in gate area, so use better name.  
> > Do you know what a gate area is?
> >
> > Because I believe gate area is kernel text, so the rename just makes it
> > redundant and more confusing.  
> 
> Yes, the gate area(eg, vectors part on ARM32, similar on x86/ia64) is 
> kernel text.
> 
> I want to keep the 'basic' section boundaries check, which only check 
> the start/end
> 
> of sections, all in section.h,  could we use 'generic' or 'basic' or 
> 'core' in the naming?
> 
>   * is_kernel_generic_data()	--- come from core_kernel_data() in kernel.h
>   * is_kernel_generic_text()
> 
> The old helper could remain unchanged, any suggestion, thanks.

Because it looks like the check of just being in the range of "_stext"
to "_end" is just an internal helper, why not do what we do all over
the kernel, and just prefix the function with a couple of underscores,
that denote that it's internal?

  __is_kernel_text()

Then you have:

 static inline int is_kernel_text(unsigned long addr)
 {
	if (__is_kernel_text(addr))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }

-- Steve

Re: [PATCH v2 5/7] kallsyms: Rename is_kernel() and is_kernel_text()

[Kefeng Wang]

On 2021/7/29 12:05, Steven Rostedt wrote:
> On Thu, 29 Jul 2021 10:00:51 +0800
> Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>> On 2021/7/28 23:28, Steven Rostedt wrote:
>>> On Wed, 28 Jul 2021 16:13:18 +0800
>>> Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>>>   
>>>> The is_kernel[_text]() function check the address whether or not
>>>> in kernel[_text] ranges, also they will check the address whether
>>>> or not in gate area, so use better name.
>>> Do you know what a gate area is?
>>>
>>> Because I believe gate area is kernel text, so the rename just makes it
>>> redundant and more confusing.
>> Yes, the gate area(eg, vectors part on ARM32, similar on x86/ia64) is
>> kernel text.
>>
>> I want to keep the 'basic' section boundaries check, which only check
>> the start/end
>>
>> of sections, all in section.h,  could we use 'generic' or 'basic' or
>> 'core' in the naming?
>>
>>    * is_kernel_generic_data()	--- come from core_kernel_data() in kernel.h
>>    * is_kernel_generic_text()
>>
>> The old helper could remain unchanged, any suggestion, thanks.
> Because it looks like the check of just being in the range of "_stext"
> to "_end" is just an internal helper, why not do what we do all over
> the kernel, and just prefix the function with a couple of underscores,
> that denote that it's internal?
>
>    __is_kernel_text()

OK， thanks for your advise,  there's already a __is_kernel_text() in 
arch/x86/mm/init_32.c,

I will change it to is_x32_kernel_text() to avoid conflict on x86_32.

>
> Then you have:
>
>   static inline int is_kernel_text(unsigned long addr)
>   {
> 	if (__is_kernel_text(addr))
>   		return 1;
>   	return in_gate_area_no_mm(addr);
>   }
>
> -- Steve
> .
>

[PATCH v2 6/7] sections: Add new is_kernel() and is_kernel_text()

[Kefeng Wang]

The new is_kernel() check the kernel address ranges, and the
new is_kernel_text() check the kernel text section ranges.

Then use them to make some code clear.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/asm-generic/sections.h | 27 +++++++++++++++++++++++++++
 include/linux/kallsyms.h       |  4 ++--
 kernel/extable.c               |  3 +--
 mm/kasan/report.c              |  2 +-
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 4f2f32aa2b7a..6b143637ab88 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -170,6 +170,20 @@ static inline bool is_kernel_rodata(unsigned long addr)
 	       addr < (unsigned long)__end_rodata;
 }
 
+/**
+ * is_kernel_text - checks if the pointer address is located in the
+ *                  .text section
+ *
+ * @addr: address to check
+ *
+ * Returns: true if the address is located in .text, false otherwise.
+ */
+static inline bool is_kernel_text(unsigned long addr)
+{
+	return addr >= (unsigned long)_stext &&
+	       addr < (unsigned long)_etext;
+}
+
 /**
  * is_kernel_inittext - checks if the pointer address is located in the
  *                    .init.text section
@@ -184,4 +198,17 @@ static inline bool is_kernel_inittext(unsigned long addr)
 	       addr < (unsigned long)_einittext;
 }
 
+/**
+ * is_kernel - checks if the pointer address is located in the kernel range
+ *
+ * @addr: address to check
+ *
+ * Returns: true if the address is located in kernel range, false otherwise.
+ */
+static inline bool is_kernel(unsigned long addr)
+{
+	return addr >= (unsigned long)_stext &&
+	       addr < (unsigned long)_end;
+}
+
 #endif /* _ASM_GENERIC_SECTIONS_H_ */
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 4f501ac9c2c2..897d5720884f 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -26,14 +26,14 @@ struct module;
 
 static inline int is_kernel_text_or_gate_area(unsigned long addr)
 {
-	if ((addr >= (unsigned long)_stext && addr < (unsigned long)_etext))
+	if (is_kernel_text(addr))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
 
 static inline int is_kernel_or_gate_area(unsigned long addr)
 {
-	if (addr >= (unsigned long)_stext && addr < (unsigned long)_end)
+	if (is_kernel(addr))
 		return 1;
 	return in_gate_area_no_mm(addr);
 }
diff --git a/kernel/extable.c b/kernel/extable.c
index 98ca627ac5ef..0ba383d850ff 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -64,8 +64,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 
 int notrace core_kernel_text(unsigned long addr)
 {
-	if (addr >= (unsigned long)_stext &&
-	    addr < (unsigned long)_etext)
+	if (is_kernel_text(addr))
 		return 1;
 
 	if (system_state < SYSTEM_RUNNING &&
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 884a950c7026..88f5b0c058b7 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -235,7 +235,7 @@ static void describe_object(struct kmem_cache *cache, void *object,
 
 static inline bool kernel_or_module_addr(const void *addr)
 {
-	if (addr >= (void *)_stext && addr < (void *)_end)
+	if (is_kernel((unsigned long)addr))
 		return true;
 	if (is_module_address((unsigned long)addr))
 		return true;
-- 
2.26.2

Re: [PATCH v2 6/7] sections: Add new is_kernel() and is_kernel_text()

[Steven Rostedt]

On Wed, 28 Jul 2021 16:13:19 +0800
Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> @@ -64,8 +64,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
>  
>  int notrace core_kernel_text(unsigned long addr)
>  {
> -	if (addr >= (unsigned long)_stext &&
> -	    addr < (unsigned long)_etext)
> +	if (is_kernel_text(addr))

Perhaps this was a bug, and these functions should be checking the gate
area as well, as that is part of kernel text.

-- Steve


>  		return 1;
>  
>  	if (system_state < SYSTEM_RUNNING &&
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 884a950c7026..88f5b0c058b7 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -235,7 +235,7 @@ static void describe_object(struct kmem_cache *cache, void *object,
>  
>  static inline bool kernel_or_module_addr(const void *addr)
>  {
> -	if (addr >= (void *)_stext && addr < (void *)_end)
> +	if (is_kernel((unsigned long)addr))
>  		return true;
>  	if (is_module_address((unsigned long)addr))
>  		return true;
> -- 

Re: [PATCH v2 6/7] sections: Add new is_kernel() and is_kernel_text()

[Kefeng Wang]

On 2021/7/28 23:32, Steven Rostedt wrote:
> On Wed, 28 Jul 2021 16:13:19 +0800
> Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>> @@ -64,8 +64,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
>>   
>>   int notrace core_kernel_text(unsigned long addr)
>>   {
>> -	if (addr >= (unsigned long)_stext &&
>> -	    addr < (unsigned long)_etext)
>> +	if (is_kernel_text(addr))
> Perhaps this was a bug, and these functions should be checking the gate
> area as well, as that is part of kernel text.
Ok, I would fix this if patch5 is reviewed well.
>
> -- Steve
>
>
>>   		return 1;
>>   
>>   	if (system_state < SYSTEM_RUNNING &&
>> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
>> index 884a950c7026..88f5b0c058b7 100644
>> --- a/mm/kasan/report.c
>> +++ b/mm/kasan/report.c
>> @@ -235,7 +235,7 @@ static void describe_object(struct kmem_cache *cache, void *object,
>>   
>>   static inline bool kernel_or_module_addr(const void *addr)
>>   {
>> -	if (addr >= (void *)_stext && addr < (void *)_end)
>> +	if (is_kernel((unsigned long)addr))
>>   		return true;
>>   	if (is_module_address((unsigned long)addr))
>>   		return true;
>> -- 
> .
>

[PATCH v2 7/7] powerpc/mm: Use is_kernel_text() and is_kernel_inittext() helper

[Kefeng Wang]

Use is_kernel_text() and is_kernel_inittext() helper to simplify code,
also drop etext, _stext, _sinittext, _einittext declaration which
already declared in section.h.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/powerpc/mm/pgtable_32.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index dcf5ecca19d9..13c798308c2e 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -33,8 +33,6 @@
 
 #include <mm/mmu_decl.h>
 
-extern char etext[], _stext[], _sinittext[], _einittext[];
-
 static u8 early_fixmap_pagetable[FIXMAP_PTE_SIZE] __page_aligned_data;
 
 notrace void __init early_ioremap_init(void)
@@ -104,14 +102,13 @@ static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
 {
 	unsigned long v, s;
 	phys_addr_t p;
-	int ktext;
+	bool ktext;
 
 	s = offset;
 	v = PAGE_OFFSET + s;
 	p = memstart_addr + s;
 	for (; s < top; s += PAGE_SIZE) {
-		ktext = ((char *)v >= _stext && (char *)v < etext) ||
-			((char *)v >= _sinittext && (char *)v < _einittext);
+		ktext = (is_kernel_text(v) || is_kernel_inittext(v));
 		map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
 		v += PAGE_SIZE;
 		p += PAGE_SIZE;
-- 
2.26.2