[Xen-devel] [PATCH] xen/lockprof: Move .lockprofile.data into .rodata

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The entire contents of .lockprofile.data are unchanging pointers to
lock_profile structure in .data.  Annotate the type as such, and link the
section in .rodata.  As these are just pointers, 32byte alignment is
unnecessary.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>

v2:
 * New
v3:
 * Explicitly introduce POINTER_ALIGN to avoid forcing 8 byte alignment on
   arm32
---
 xen/arch/arm/xen.lds.S       | 15 ++++++++-------
 xen/arch/x86/xen.lds.S       | 14 +++++++-------
 xen/include/asm-arm/config.h |  1 +
 xen/include/asm-x86/config.h |  1 +
 xen/include/xen/spinlock.h   |  2 +-
 5 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index f501a2f..1b5e516 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -50,6 +50,14 @@ SECTIONS
        __stop_bug_frames_2 = .;
        *(.rodata)
        *(.rodata.*)
+
+#ifdef LOCK_PROFILE
+       . = ALIGN(POINTER_ALIGN);
+       __lock_profile_start = .;
+       *(.lockprofile.data)
+       __lock_profile_end = .;
+#endif
+
         _erodata = .;          /* End of read-only data */
   } :text
 
@@ -83,13 +91,6 @@ SECTIONS
        *(.data.rel.ro.*)
   } :text
 
-#ifdef LOCK_PROFILE
-  . = ALIGN(32);
-  __lock_profile_start = .;
-  .lockprofile.data : { *(.lockprofile.data) } :text
-  __lock_profile_end = .;
-#endif
-
   . = ALIGN(8);
   .arch.info : {
       _splatform = .;
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 9fde1db..8390ec2 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -65,6 +65,13 @@ SECTIONS
 
        *(.rodata)
        *(.rodata.*)
+
+#ifdef LOCK_PROFILE
+       . = ALIGN(POINTER_ALIGN);
+       __lock_profile_start = .;
+       *(.lockprofile.data)
+       __lock_profile_end = .;
+#endif
   } :text
 
   . = ALIGN(SMP_CACHE_BYTES);
@@ -97,13 +104,6 @@ SECTIONS
        CONSTRUCTORS
   } :text
 
-#ifdef LOCK_PROFILE
-  . = ALIGN(32);
-  __lock_profile_start = .;
-  .lockprofile.data : { *(.lockprofile.data) } :text
-  __lock_profile_end = .;
-#endif
-
   . = ALIGN(PAGE_SIZE);             /* Init code and data */
   __init_begin = .;
   .init.text : {
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index c3a2c30..c0ad469 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -15,6 +15,7 @@
 
 #define BYTES_PER_LONG (1 << LONG_BYTEORDER)
 #define BITS_PER_LONG (BYTES_PER_LONG << 3)
+#define POINTER_ALIGN BYTES_PER_LONG
 
 /* xen_ulong_t is always 64 bits */
 #define BITS_PER_XEN_ULONG 64
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index 07f3c1f..7291b59 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -13,6 +13,7 @@
 #define BYTES_PER_LONG (1 << LONG_BYTEORDER)
 #define BITS_PER_LONG (BYTES_PER_LONG << 3)
 #define BITS_PER_BYTE 8
+#define POINTER_ALIGN BYTES_PER_LONG
 
 #define BITS_PER_XEN_ULONG BITS_PER_LONG
 
diff --git a/xen/include/xen/spinlock.h b/xen/include/xen/spinlock.h
index 77ab7d5..88b53f9 100644
--- a/xen/include/xen/spinlock.h
+++ b/xen/include/xen/spinlock.h
@@ -79,7 +79,7 @@ struct lock_profile_qhead {
 
 #define _LOCK_PROFILE(name) { 0, #name, &name, 0, 0, 0, 0, 0 }
 #define _LOCK_PROFILE_PTR(name)                                               \
-    static struct lock_profile *__lock_profile_##name                         \
+    static struct lock_profile * const __lock_profile_##name                  \
     __used_section(".lockprofile.data") =                                     \
     &__lock_profile_data_##name
 #define _SPIN_LOCK_UNLOCKED(x) { { 0 }, SPINLOCK_NO_CPU, 0, _LOCK_DEBUG, x }
-- 
2.1.4


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