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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v7 4/4] xen/common: use SYMBOL_HIDE when required
On Thu, 10 Jan 2019, Stefano Stabellini wrote:
> diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
> index 548b64d..3fa56ff 100644
> --- a/xen/include/xen/kernel.h
> +++ b/xen/include/xen/kernel.h
> @@ -66,27 +66,27 @@
> })
>
> extern char _start[], _end[], start[];
> -#define is_kernel(p) ({ \
> - char *__p = (char *)(unsigned long)(p); \
> - (__p >= _start) && (__p < _end); \
> +#define is_kernel(p) ({ \
> + const char *p__ = (char *)(unsigned long)(p); \
> + (p__ >= SYMBOL_HIDE(_start)) && (p__ < SYMBOL_HIDE(_end)); \
> })
>
> extern char _stext[], _etext[];
> -#define is_kernel_text(p) ({ \
> - char *__p = (char *)(unsigned long)(p); \
> - (__p >= _stext) && (__p < _etext); \
> +#define is_kernel_text(p) ({ \
> + const char *p__ = (char *)(unsigned long)(p); \
> + (p__ >= SYMBOL_HIDE(_stext)) && (p__ < SYMBOL_HIDE(_etext)); \
> })
>
> extern const char _srodata[], _erodata[];
> -#define is_kernel_rodata(p) ({ \
> - const char *__p = (const char *)(unsigned long)(p); \
> - (__p >= _srodata) && (__p < _erodata); \
> +#define is_kernel_rodata(p) ({ \
> + const char *p__ = (const char *)(unsigned long)(p); \
> + (p__ >= SYMBOL_HIDE(_srodata)) && (p__ < SYMBOL_HIDE(_erodata));\
> })
>
> extern char _sinittext[], _einittext[];
> -#define is_kernel_inittext(p) ({ \
> - char *__p = (char *)(unsigned long)(p); \
> - (__p >= _sinittext) && (__p < _einittext); \
> +#define is_kernel_inittext(p) ({ \
> + const char *p__ = (char *)(unsigned long)(p); \
> + (p__ >= SYMBOL_HIDE(_sinittext)) && (p__ < SYMBOL_HIDE(_einittext)); \
> })
I have just realized that it would be nicer to also switch the casts to
const char*. See patch below with this small change:
From 7fa76d73b275285ccf942eb0397ae52fb18fa683 Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Date: Thu, 10 Jan 2019 10:50:41 -0800
Subject: [PATCH] xen/common: use SYMBOL_HIDE when required
Use SYMBOL_HIDE in cases of comparisons and subtractions of:
_start, _end, _stext, _etext, _srodata, _erodata, _sinittext,
_einittext, __note_gnu_build_id_start, __note_gnu_build_id_end,
__lock_profile_start, __lock_profile_end, __initcall_start,
__initcall_end, __presmp_initcall_end, __ctors_start, __ctors_end,
__end_schedulers_array, __start_schedulers_array, __start_bug_frames,
__stop_bug_frames_0, __stop_bug_frames_1, __stop_bug_frames_2,
__stop_bug_frames_3,
as by the C standard [1].
M3CM: Rule-18.2: Subtraction between pointers shall only be applied to
pointers that address elements of the same array
Since we are changing the body of is_kernel_text and friends, take the
opportunity to remove the leading underscores in the local variables
names, which are violationg namespace rules. Also make the local p__
variable const.
[1]
https://wiki.sei.cmu.edu/confluence/display/c/ARR36-C.+Do+not+subtract+or+compare+two+pointers+that+do+not+refer+to+the+same+array
QAVerify: 2761
Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
CC: JBeulich@xxxxxxxx
CC: andrew.cooper3@xxxxxxxxxx
---
Changes in v7:
- add back second const in bug_frames
- switch from void* casts to unsigned long casts in xen_build_init
- switch p__ to const char*
- rename SYMBOL to SYMBOL_HIDE
Changes in v6:
- more accurate commit message
- remove hard tabs
- remove leading underscores
- code style
- use SYMBOL_HIDE only on the problematic bug_frames symbols
- use new SYMBOL_HIDE macro that returns the native type
Changes in v5:
- remove two spurious changes
- split into three patches
- remove SYMBOL_HIDE() from derived variables
---
xen/common/kernel.c | 8 ++++++--
xen/common/lib.c | 3 ++-
xen/common/schedule.c | 6 ++++--
xen/common/spinlock.c | 4 +++-
xen/common/version.c | 6 +++---
xen/common/virtual_region.c | 12 ++++++------
xen/include/xen/kernel.h | 24 ++++++++++++------------
7 files changed, 36 insertions(+), 27 deletions(-)
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 5766a0f..e546ba1 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -312,14 +312,18 @@ extern const initcall_t __initcall_start[],
__presmp_initcall_end[],
void __init do_presmp_initcalls(void)
{
const initcall_t *call;
- for ( call = __initcall_start; call < __presmp_initcall_end; call++ )
+ for ( call = SYMBOL_HIDE(__initcall_start);
+ call < SYMBOL_HIDE(__presmp_initcall_end);
+ call++ )
(*call)();
}
void __init do_initcalls(void)
{
const initcall_t *call;
- for ( call = __presmp_initcall_end; call < __initcall_end; call++ )
+ for ( call = SYMBOL_HIDE(__presmp_initcall_end);
+ call < SYMBOL_HIDE(__initcall_end);
+ call++ )
(*call)();
}
diff --git a/xen/common/lib.c b/xen/common/lib.c
index 8ebec81..a788a1c 100644
--- a/xen/common/lib.c
+++ b/xen/common/lib.c
@@ -497,7 +497,8 @@ extern const ctor_func_t __ctors_start[], __ctors_end[];
void __init init_constructors(void)
{
const ctor_func_t *f;
- for ( f = __ctors_start; f < __ctors_end; ++f )
+
+ for ( f = SYMBOL_HIDE(__ctors_start); f < SYMBOL_HIDE(__ctors_end); ++f )
(*f)();
/* Putting this here seems as good (or bad) as any other place. */
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index a957c5e..3e00fcf 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -67,8 +67,10 @@ DEFINE_PER_CPU(struct scheduler *, scheduler);
/* Scratch space for cpumasks. */
DEFINE_PER_CPU(cpumask_t, cpumask_scratch);
-extern const struct scheduler *__start_schedulers_array[],
*__end_schedulers_array[];
-#define NUM_SCHEDULERS (__end_schedulers_array - __start_schedulers_array)
+extern const struct scheduler *__start_schedulers_array[],
+ *__end_schedulers_array[];
+#define NUM_SCHEDULERS (SYMBOL_HIDE(__end_schedulers_array) - \
+ SYMBOL_HIDE(__start_schedulers_array))
#define schedulers __start_schedulers_array
static struct scheduler __read_mostly ops;
diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index 6bc52d7..a870f03 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -474,7 +474,9 @@ static int __init lock_prof_init(void)
{
struct lock_profile **q;
- for ( q = &__lock_profile_start; q < &__lock_profile_end; q++ )
+ for ( q = SYMBOL_HIDE(&__lock_profile_start);
+ q < SYMBOL_HIDE(&__lock_profile_end);
+ q++ )
{
(*q)->next = lock_profile_glb_q.elem_q;
lock_profile_glb_q.elem_q = *q;
diff --git a/xen/common/version.c b/xen/common/version.c
index 223cb52..e882793 100644
--- a/xen/common/version.c
+++ b/xen/common/version.c
@@ -147,14 +147,14 @@ static int __init xen_build_init(void)
int rc;
/* --build-id invoked with wrong parameters. */
- if ( __note_gnu_build_id_end <= &n[0] )
+ if ( SYMBOL_HIDE(__note_gnu_build_id_end) <= &n[0] )
return -ENODATA;
/* Check for full Note header. */
- if ( &n[1] >= __note_gnu_build_id_end )
+ if ( &n[1] >= SYMBOL_HIDE(__note_gnu_build_id_end) )
return -ENODATA;
- sz = (void *)__note_gnu_build_id_end - (void *)n;
+ sz = (unsigned long)SYMBOL_HIDE(__note_gnu_build_id_end) - (unsigned
long)n;
rc = xen_build_id_check(n, sz, &build_id_p, &build_id_len);
diff --git a/xen/common/virtual_region.c b/xen/common/virtual_region.c
index aa23918..cd7f373 100644
--- a/xen/common/virtual_region.c
+++ b/xen/common/virtual_region.c
@@ -103,13 +103,13 @@ void __init setup_virtual_regions(const struct
exception_table_entry *start,
{
size_t sz;
unsigned int i;
- static const struct bug_frame *const __initconstrel bug_frames[] = {
- __start_bug_frames,
- __stop_bug_frames_0,
- __stop_bug_frames_1,
- __stop_bug_frames_2,
+ const struct bug_frame *const bug_frames[] = {
+ SYMBOL_HIDE(__start_bug_frames),
+ SYMBOL_HIDE(__stop_bug_frames_0),
+ SYMBOL_HIDE(__stop_bug_frames_1),
+ SYMBOL_HIDE(__stop_bug_frames_2),
#ifdef CONFIG_X86
- __stop_bug_frames_3,
+ SYMBOL_HIDE(__stop_bug_frames_3),
#endif
NULL
};
diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
index 548b64d..0733dfe 100644
--- a/xen/include/xen/kernel.h
+++ b/xen/include/xen/kernel.h
@@ -66,27 +66,27 @@
})
extern char _start[], _end[], start[];
-#define is_kernel(p) ({ \
- char *__p = (char *)(unsigned long)(p); \
- (__p >= _start) && (__p < _end); \
+#define is_kernel(p) ({ \
+ const char *p__ = (const char *)(unsigned long)(p); \
+ (p__ >= SYMBOL_HIDE(_start)) && (p__ < SYMBOL_HIDE(_end)); \
})
extern char _stext[], _etext[];
-#define is_kernel_text(p) ({ \
- char *__p = (char *)(unsigned long)(p); \
- (__p >= _stext) && (__p < _etext); \
+#define is_kernel_text(p) ({ \
+ const char *p__ = (const char *)(unsigned long)(p); \
+ (p__ >= SYMBOL_HIDE(_stext)) && (p__ < SYMBOL_HIDE(_etext)); \
})
extern const char _srodata[], _erodata[];
-#define is_kernel_rodata(p) ({ \
- const char *__p = (const char *)(unsigned long)(p); \
- (__p >= _srodata) && (__p < _erodata); \
+#define is_kernel_rodata(p) ({ \
+ const char *p__ = (const char *)(unsigned long)(p); \
+ (p__ >= SYMBOL_HIDE(_srodata)) && (p__ < SYMBOL_HIDE(_erodata));\
})
extern char _sinittext[], _einittext[];
-#define is_kernel_inittext(p) ({ \
- char *__p = (char *)(unsigned long)(p); \
- (__p >= _sinittext) && (__p < _einittext); \
+#define is_kernel_inittext(p) ({ \
+ const char *p__ = (const char *)(unsigned long)(p); \
+ (p__ >= SYMBOL_HIDE(_sinittext)) && (p__ < SYMBOL_HIDE(_einittext)); \
})
extern enum system_state {
--
1.9.1
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