percpu: Per cpu code simplification fixup

PATCH In review [email protected] 4 participants 13 messages Jan 18, 2008 – Jan 21, 2008

Subsystems (6)

Memory management x86 PowerPC Library code +2 more subsystems

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[email protected]

author

2008-01-18 18:29 UTC #0 lore raw

cover percpu: Per cpu code simplification fixup

This patchset simplifies the code that arches need to maintain to support per cpu functionality. Most of the code is moved into arch independent code. Only a minimal set of definitions is kept for each arch.

The patch also unifies the x86 arch so that there is only a single asm-x86/percpu.h

Based on: 2.6.24-rc8-mm1

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---

fixup:

- rebased from 2.6.24-rc6-mm1 to 2.6.24-rc8-mm1 (removed changes that are in the git-x86.patch)
- added back in missing fold-percpu_modcopy pieces

V3->V4:
- rebased patchset on 2.6.24-rc6-mm1
(removes the percpu_modcopy changes that are already in.)
- change config ARCH_SETS_UP_PER_CPU_AREA to a global var and use select HAVE_SETUP_PER_CPU_AREA to specify.

V2->V3:
- fix x86_64 non-SMP case
- change SHIFT_PTR to SHIFT_PERCPU_PTR
- fix various percpu_modcopy()'s to reference correct per_cpu_offset()
- s390 has a special way to determine the pointer to a per cpu area

V1->V2:
- Add support for specifying attributes for per cpu declarations (preserves IA64 model(small) attribute).
- Drop first patch that removes the model(small) attribute for IA64
- Missing #endif in powerpc generic config / Wrong Kconfig
- Follow Randy's suggestions on how to do the Kconfig settings

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author

2008-01-18 18:29 UTC #1 lore raw

PATCH 1/7 Modules: Fold percpu_modcopy into module.c

percpu_modcopy() is defined multiple times in arch files. However, the only user is module.c. Put a static definition into module.c and remove the definitions from the arch files.

Cc Rusty Russell <[email protected]>

Cc Andi Kleen <[email protected]>

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---
 arch/ia64/kernel/module.c    |   11 -----------
 include/asm-generic/percpu.h |    8 --------
 include/asm-ia64/percpu.h    |    5 -----
 include/asm-powerpc/percpu.h |    9 ---------
 include/asm-s390/percpu.h    |    9 ---------
 kernel/module.c              |    8 ++++++++
 6 files changed, 8 insertions(+), 42 deletions(-)

arch/ia64/kernel/module.c +0 ~~-11~~

@@ -940,14 +940,3 @@ module_arch_cleanup (struct module *mod)
 	if (mod->arch.core_unw_table)
 		unw_remove_unwind_table(mod->arch.core_unw_table);
 }
-
-#ifdef CONFIG_SMP
-void
-percpu_modcopy (void *pcpudst, const void *src, unsigned long size)
-{
-	unsigned int i;
-	for_each_possible_cpu(i) {
-		memcpy(pcpudst + per_cpu_offset(i), src, size);
-	}
-}
-#endif /* CONFIG_SMP */

include/asm-generic/percpu.h +0 -8

@@ -63,14 +63,6 @@ extern unsigned long __per_cpu_offset[NR
 extern void setup_per_cpu_areas(void);
 #endif
 
-/* A macro to avoid #include hell... */
-#define percpu_modcopy(pcpudst, src, size)			\
-do {								\
-	unsigned int __i;					\
-	for_each_possible_cpu(__i)				\
-		memcpy((pcpudst)+per_cpu_offset(__i),		\
-		       (src), (size));				\
-} while (0)
 #else /* ! SMP */
 
 #define per_cpu(var, cpu)			(*((void)(cpu), &per_cpu_var(var)))

include/asm-ia64/percpu.h +0 -5

@@ -22,10 +22,6 @@
 #define DECLARE_PER_CPU(type, name)				\
 	extern PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
 
-/*
- * Pretty much a literal copy of asm-generic/percpu.h, except that percpu_modcopy() is an
- * external routine, to avoid include-hell.
- */
 #ifdef CONFIG_SMP
 
 extern unsigned long __per_cpu_offset[NR_CPUS];

@@ -38,7 +34,6 @@ DECLARE_PER_CPU(unsigned long, local_per
 #define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __ia64_per_cpu_var(local_per_cpu_offset)))
 #define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __ia64_per_cpu_var(local_per_cpu_offset)))
 
-extern void percpu_modcopy(void *pcpudst, const void *src, unsigned long size);
 extern void setup_per_cpu_areas (void);
 extern void *per_cpu_init(void);

include/asm-powerpc/percpu.h +0 -9

@@ -21,15 +21,6 @@
 #define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
 #define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, local_paca->data_offset))
 
-/* A macro to avoid #include hell... */
-#define percpu_modcopy(pcpudst, src, size)			\
-do {								\
-	unsigned int __i;					\
-	for_each_possible_cpu(__i)				\
-		memcpy((pcpudst)+__per_cpu_offset(__i),		\
-		       (src), (size));				\
-} while (0)
-
 extern void setup_per_cpu_areas(void);
 
 #else /* ! SMP */

include/asm-s390/percpu.h +0 -9

@@ -39,15 +39,6 @@ extern unsigned long __per_cpu_offset[NR
 #define per_cpu(var,cpu) __reloc_hide(var,__per_cpu_offset[cpu])
 #define per_cpu_offset(x) (__per_cpu_offset[x])
 
-/* A macro to avoid #include hell... */
-#define percpu_modcopy(pcpudst, src, size)			\
-do {								\
-	unsigned int __i;					\
-	for_each_possible_cpu(__i)				\
-		memcpy((pcpudst)+__per_cpu_offset[__i],		\
-		       (src), (size));				\
-} while (0)
-
 #else /* ! SMP */
 
 #define __get_cpu_var(var) __reloc_hide(var,0)

kernel/module.c +8 -0

@@ -422,6 +422,14 @@ static unsigned int find_pcpusec(Elf_Ehd
 	return find_sec(hdr, sechdrs, secstrings, ".data.percpu");
 }
 
+static void percpu_modcopy(void *pcpudest, const void *from, unsigned long size)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		memcpy(pcpudest + per_cpu_offset(cpu), from, size);
+}
+
 static int percpu_modinit(void)
 {
 	pcpu_num_used = 2;

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Rusty Russell

Acked-by on v1 1/7

2008-01-18 19:46 UTC #2 lore raw

Re: [PATCH 1/7] Modules: Fold percpu_modcopy into module.c

Quoted 3 lines · On Saturday 19 January 2008 05:29:54 [email protected] wrote:

percpu_modcopy() is defined multiple times in arch files. However, the only user is module.c. Put a static definition into module.c and remove the definitions from the arch files.

Acked-by Rusty Russell <[email protected]>

Thanks!
Rusty.

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David Miller

2008-01-21 08:08 UTC #3 lore raw

Re: [PATCH 1/7] Modules: Fold percpu_modcopy into module.c

In reply to [email protected]

Quoted 8 lines

percpu_modcopy() is defined multiple times in arch files. However, the only user is module.c. Put a static definition into module.c and remove the definitions from the arch files.
Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Signed-off-by Christoph Lameter <[email protected]>
Signed-off-by Mike Travis <[email protected]>

This doesn't build on sparc64.

The percpu_modcopy() removal from include/asm-sparc64/percpu.h leaked into patch #3 instead of being done here in patch #1 where it belongs (so that this series is properly bisectable).

It also seems that the include/asm-x86/percpu_{32,64}.h defines aren't removed in this patch either.

Mike Travis

author

2008-01-21 15:41 UTC #4 lore raw

Re: [PATCH 1/7] Modules: Fold percpu_modcopy into module.c

Quoted 12 lines · David Miller

From: [email protected]
Date: Fri, 18 Jan 2008 10:29:54 -0800
Quoted 8 lines
percpu_modcopy() is defined multiple times in arch files. However, the only user is module.c. Put a static definition into module.c and remove the definitions from the arch files.
Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Signed-off-by Christoph Lameter <[email protected]>
Signed-off-by Mike Travis <[email protected]>

Quoted 8 lines

This doesn't build on sparc64.
The percpu_modcopy() removal from include/asm-sparc64/percpu.h leaked into patch #3 instead of being done here in patch #1 where it belongs (so that this series is properly bisectable).
It also seems that the include/asm-x86/percpu_{32,64}.h defines aren't removed in this patch either.

Hi,

I think I have this fixed in the newest version. Yes, it's been a hat dance with some changes coming through the git-x86 patch and others not. I'll submit the new one shortly.

Thanks,
Mike

[email protected]

author

2008-01-18 18:29 UTC #5 lore raw

PATCH 2/7 percpu: Change Kconfig ARCH_SETS_UP_PER_CPU_AREA to HAVE_SETUP_PER_CPU_AREA

In reply to [email protected]

Change "config ARCH_SETS_UP_PER_CPU_AREA" to "select HAVE_SETUP_PER_CPU_AREA" as suggested by Sam.

Cc Rusty Russell <[email protected]>

Cc Andi Kleen <[email protected]>

Cc Sam Ravnborg <[email protected]>

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---
 arch/Kconfig                 |    3 +++
 arch/ia64/Kconfig            |    4 +---
 arch/powerpc/Kconfig         |    4 +---
 arch/sparc64/Kconfig         |    4 +---
 arch/x86/Kconfig             |    4 +---
 include/asm-generic/percpu.h |    2 +-
 init/main.c                  |    4 ++--
 7 files changed, 10 insertions(+), 15 deletions(-)

arch/Kconfig +3 -0

@@ -1,3 +1,6 @@
 #
 # General architecture dependent options
 #
+
+config HAVE_SETUP_PER_CPU_AREA
+	def_bool n

arch/ia64/Kconfig +1 -3

@@ -17,6 +17,7 @@ config IA64
 	select ARCH_SUPPORTS_MSI
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_SETUP_PER_CPU_AREA
 	default y
 	help
 	  The Itanium Processor Family is Intel's 64-bit successor to

@@ -82,9 +83,6 @@ config GENERIC_TIME_VSYSCALL
 	bool
 	default y
 
-config ARCH_SETS_UP_PER_CPU_AREA
-	def_bool y
-
 config DMI
 	bool
 	default y

arch/powerpc/Kconfig +1 -3

@@ -42,9 +42,6 @@ config GENERIC_HARDIRQS
 	bool
 	default y
 
-config ARCH_SETS_UP_PER_CPU_AREA
-	def_bool PPC64
-
 config IRQ_PER_CPU
 	bool
 	default y

@@ -89,6 +86,7 @@ config PPC
 	default y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_SETUP_PER_CPU_AREA if PPC64
 
 config EARLY_PRINTK
 	bool

arch/sparc64/Kconfig +1 -3

@@ -10,6 +10,7 @@ config SPARC
 	default y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_SETUP_PER_CPU_AREA
 
 config SPARC64
 	bool

@@ -68,9 +69,6 @@ config AUDIT_ARCH
 	bool
 	default y
 
-config ARCH_SETS_UP_PER_CPU_AREA
-	def_bool y
-
 config ARCH_NO_VIRT_TO_BUS
 	def_bool y

arch/x86/Kconfig +1 -3

@@ -20,6 +20,7 @@ config X86
 	def_bool y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_SETUP_PER_CPU_AREA if X86_64
 
 config GENERIC_LOCKBREAK
 	def_bool n

@@ -106,9 +107,6 @@ config GENERIC_TIME_VSYSCALL
 	bool
 	default X86_64
 
-config ARCH_SETS_UP_PER_CPU_AREA
-	def_bool X86_64
-
 config ARCH_SUPPORTS_OPROFILE
 	bool
 	default y

include/asm-generic/percpu.h +1 -1

@@ -59,7 +59,7 @@ extern unsigned long __per_cpu_offset[NR
 	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))
 
 
-#ifdef CONFIG_ARCH_SETS_UP_PER_CPU_AREA
+#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
 extern void setup_per_cpu_areas(void);
 #endif

init/main.c +2 -2

@@ -363,7 +363,7 @@ static inline void smp_prepare_cpus(unsi
 
 #else
 
-#ifndef CONFIG_ARCH_SETS_UP_PER_CPU_AREA
+#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
 
 EXPORT_SYMBOL(__per_cpu_offset);

@@ -384,7 +384,7 @@ static void __init setup_per_cpu_areas(v
 		ptr += size;
 	}
 }
-#endif /* CONFIG_ARCH_SETS_UP_CPU_AREA */
+#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
 
 /* Called by boot processor to activate the rest. */
 static void __init smp_init(void)

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author

2008-01-18 18:29 UTC #6 lore raw

PATCH 3/7 Sparc64: Use generic percpu

In reply to [email protected]

Sparc64 has a way of providing the base address for the per cpu area of the currently executing processor in a global register.

Sparc64 also provides a way to calculate the address of a per cpu area from a base address instead of performing an array lookup.

Cc David Miller <[email protected]>

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---
 arch/sparc64/mm/init.c       |    5 +++++
 include/asm-sparc64/percpu.h |   22 +++-------------------
 2 files changed, 8 insertions(+), 19 deletions(-)

arch/sparc64/mm/init.c +5 -0

@@ -1328,6 +1328,11 @@ pgd_t swapper_pg_dir[2048];
 static void sun4u_pgprot_init(void);
 static void sun4v_pgprot_init(void);
 
+/* Dummy function */
+void __init setup_per_cpu_areas(void)
+{
+}
+
 void __init paging_init(void)
 {
 	unsigned long end_pfn, pages_avail, shift, phys_base;

include/asm-sparc64/percpu.h +3 ~~-19~~

@@ -7,7 +7,6 @@ register unsigned long __local_per_cpu_o
 
 #ifdef CONFIG_SMP
 
-#define setup_per_cpu_areas()			do { } while (0)
 extern void real_setup_per_cpu_areas(void);
 
 extern unsigned long __per_cpu_base;

@@ -16,29 +15,14 @@ extern unsigned long __per_cpu_shift;
 	(__per_cpu_base + ((unsigned long)(__cpu) << __per_cpu_shift))
 #define per_cpu_offset(x) (__per_cpu_offset(x))
 
-/* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset(cpu)))
-#define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __local_per_cpu_offset))
-#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __local_per_cpu_offset))
-
-/* A macro to avoid #include hell... */
-#define percpu_modcopy(pcpudst, src, size)			\
-do {								\
-	unsigned int __i;					\
-	for_each_possible_cpu(__i)				\
-		memcpy((pcpudst)+__per_cpu_offset(__i),		\
-		       (src), (size));				\
-} while (0)
+#define __my_cpu_offset __local_per_cpu_offset
+
 #else /* ! SMP */
 
 #define real_setup_per_cpu_areas()		do { } while (0)
 
-#define per_cpu(var, cpu)			(*((void)cpu, &per_cpu__##var))
-#define __get_cpu_var(var)			per_cpu__##var
-#define __raw_get_cpu_var(var)			per_cpu__##var
-
 #endif	/* SMP */
 
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
+#include <asm-generic/percpu.h>
 
 #endif /* __ARCH_SPARC64_PERCPU__ */

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author

2008-01-18 18:29 UTC #7 lore raw

PATCH 4/7 ia64: Use generic percpu

In reply to [email protected]

ia64 has a special processor specific mapping that can be used to locate the offset for the current per cpu area.

Cc [email protected]

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---

V1->V2:
- Merge fixes
- Remove transitional check for PER_CPU_ATTRIBUTES from linux/percpu.h

V2-.V3:
- use generic percpy_modcopy()

---
 include/asm-ia64/percpu.h |   24 +++++++-----------------
 include/linux/percpu.h    |    4 ----
 2 files changed, 7 insertions(+), 21 deletions(-)

include/asm-ia64/percpu.h +7 ~~-17~~

@@ -19,29 +19,14 @@
 # define PER_CPU_ATTRIBUTES	__attribute__((__model__ (__small__)))
 #endif
 
-#define DECLARE_PER_CPU(type, name)				\
-	extern PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
-
 #ifdef CONFIG_SMP
 
-extern unsigned long __per_cpu_offset[NR_CPUS];
-#define per_cpu_offset(x) (__per_cpu_offset[x])
-
-/* Equal to __per_cpu_offset[smp_processor_id()], but faster to access: */
-DECLARE_PER_CPU(unsigned long, local_per_cpu_offset);
-
-#define per_cpu(var, cpu)  (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
-#define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __ia64_per_cpu_var(local_per_cpu_offset)))
-#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __ia64_per_cpu_var(local_per_cpu_offset)))
+#define __my_cpu_offset	__ia64_per_cpu_var(local_per_cpu_offset)
 
-extern void setup_per_cpu_areas (void);
 extern void *per_cpu_init(void);
 
 #else /* ! SMP */
 
-#define per_cpu(var, cpu)			(*((void)(cpu), &per_cpu__##var))
-#define __get_cpu_var(var)			per_cpu__##var
-#define __raw_get_cpu_var(var)			per_cpu__##var
 #define per_cpu_init()				(__phys_per_cpu_start)
 
 #endif	/* SMP */

@@ -52,7 +37,12 @@ extern void *per_cpu_init(void);
  * On the positive side, using __ia64_per_cpu_var() instead of __get_cpu_var() is slightly
  * more efficient.
  */
-#define __ia64_per_cpu_var(var)	(per_cpu__##var)
+#define __ia64_per_cpu_var(var)	per_cpu__##var
+
+#include <asm-generic/percpu.h>
+
+/* Equal to __per_cpu_offset[smp_processor_id()], but faster to access: */
+DECLARE_PER_CPU(unsigned long, local_per_cpu_offset);
 
 #endif /* !__ASSEMBLY__ */

include/linux/percpu.h +0 -4

@@ -9,10 +9,6 @@
 
 #include <asm/percpu.h>
 
-#ifndef PER_CPU_ATTRIBUTES
-#define PER_CPU_ATTRIBUTES
-#endif
-
 #ifdef CONFIG_SMP
 #define DEFINE_PER_CPU(type, name)					\
 	__attribute__((__section__(".data.percpu")))			\

[email protected]

author

2008-01-18 18:29 UTC #8 lore raw

PATCH 5/7 Powerpc: Use generic per cpu

In reply to [email protected]

Powerpc has a way to determine the address of the per cpu area of the currently executing processor via the paca and the array of per cpu offsets is avoided by looking up the per cpu area from the remote paca's (copying x86_64).

Cc Paul Mackerras <[email protected]>

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---

V1->V2:
- add missing #endif

V2->V3:
- use generic percpy_modcopy()

---
 include/asm-powerpc/percpu.h |   20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

include/asm-powerpc/percpu.h +2 ~~-18~~

@@ -16,25 +16,9 @@
 #define __my_cpu_offset() get_paca()->data_offset
 #define per_cpu_offset(x) (__per_cpu_offset(x))
 
-/* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset(cpu)))
-#define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
-#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, local_paca->data_offset))
+#endif /* CONFIG_SMP */
+#endif /* __powerpc64__ */
 
-extern void setup_per_cpu_areas(void);
-
-#else /* ! SMP */
-
-#define per_cpu(var, cpu)			(*((void)(cpu), &per_cpu__##var))
-#define __get_cpu_var(var)			per_cpu__##var
-#define __raw_get_cpu_var(var)			per_cpu__##var
-
-#endif	/* SMP */
-
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
-
-#else
 #include <asm-generic/percpu.h>
-#endif
 
 #endif /* _ASM_POWERPC_PERCPU_H_ */

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author

2008-01-18 18:29 UTC #9 lore raw

PATCH 6/7 s390: Use generic percpu

In reply to [email protected]

Change s390 percpu.h to use asm-generic/percpu.h

Cc [email protected]

Signed-off-by Christoph Lameter <[email protected]>

Signed-off-by Mike Travis <[email protected]>

---

V2->V3:

Quoted 8 lines · Martin Schwidefsky

Quoted 6 lines · Christoph Lameter
s390 has a special way to determine the pointer to a per cpu area plus there is a way to access the base of the per cpu area of the currently executing processor.
Note: I had to do a minor change to ASM code. Please check that this was done right.

Quoted 6 lines

Hi Christoph,
after fixing the trainwreck with Gregs kset changes I've got rc3-mm2 compiled with your percpu patches. The new s390 percpu code works fine:
Acked-by Martin Schwidefsky <[email protected]>

---
 include/asm-s390/percpu.h |   33 +++++++++------------------------
 1 file changed, 9 insertions(+), 24 deletions(-)

include/asm-s390/percpu.h +9 ~~-24~~

@@ -13,40 +13,25 @@
  */
 #if defined(__s390x__) && defined(MODULE)
 
-#define __reloc_hide(var,offset) (*({			\
+#define SHIFT_PERCPU_PTR(ptr,offset) (({			\
 	extern int simple_identifier_##var(void);	\
 	unsigned long *__ptr;				\
-	asm ( "larl %0,per_cpu__"#var"@GOTENT"		\
-	    : "=a" (__ptr) : "X" (per_cpu__##var) );	\
-	(typeof(&per_cpu__##var))((*__ptr) + (offset));	}))
+	asm ( "larl %0, %1@GOTENT"		\
+	    : "=a" (__ptr) : "X" (ptr) );		\
+	(typeof(ptr))((*__ptr) + (offset));	}))
 
 #else
 
-#define __reloc_hide(var, offset) (*({				\
+#define SHIFT_PERCPU_PTR(ptr, offset) (({				\
 	extern int simple_identifier_##var(void);		\
 	unsigned long __ptr;					\
-	asm ( "" : "=a" (__ptr) : "0" (&per_cpu__##var) );	\
-	(typeof(&per_cpu__##var)) (__ptr + (offset)); }))
+	asm ( "" : "=a" (__ptr) : "0" (ptr) );			\
+	(typeof(ptr)) (__ptr + (offset)); }))
 
 #endif
 
-#ifdef CONFIG_SMP
+#define __my_cpu_offset S390_lowcore.percpu_offset
 
-extern unsigned long __per_cpu_offset[NR_CPUS];
-
-#define __get_cpu_var(var) __reloc_hide(var,S390_lowcore.percpu_offset)
-#define __raw_get_cpu_var(var) __reloc_hide(var,S390_lowcore.percpu_offset)
-#define per_cpu(var,cpu) __reloc_hide(var,__per_cpu_offset[cpu])
-#define per_cpu_offset(x) (__per_cpu_offset[x])
-
-#else /* ! SMP */
-
-#define __get_cpu_var(var) __reloc_hide(var,0)
-#define __raw_get_cpu_var(var) __reloc_hide(var,0)
-#define per_cpu(var,cpu) __reloc_hide(var,0)
-
-#endif /* SMP */
-
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
+#include <asm-generic/percpu.h>
 
 #endif /* __ARCH_S390_PERCPU__ */

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[email protected]

author

2008-01-18 18:30 UTC #10 lore raw

PATCH 7/7 percpu: Add debug detection of uninitialized usage of per_cpu variable

In reply to [email protected]

Provide a means to trap usages of per_cpu variables before the per_cpu_areas are setup. Define CONFIG_DEBUG_PER_CPU to activate.

Signed-off-by Mike Travis <[email protected]>

---
 include/asm-generic/percpu.h |   11 ++++++++++-
 lib/Kconfig.debug            |   12 ++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

include/asm-generic/percpu.h +10 -1

@@ -47,12 +47,21 @@ extern unsigned long __per_cpu_offset[NR
 #endif
 
 /*
- * A percpu variable may point to a discarded reghions. The following are
+ * A percpu variable may point to a discarded regions. The following are
  * established ways to produce a usable pointer from the percpu variable
  * offset.
  */
+#ifdef	CONFIG_DEBUG_PER_CPU
+#define per_cpu(var, cpu) (*({		\
+	if(!per_cpu_offset(cpu)) {	\
+		printk("KERN_NOTICE per_cpu(%s,%d): not available!\n", #var, (int)cpu); \
+		BUG();			\
+	}				\
+	SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu));}))
+#else
 #define per_cpu(var, cpu) \
 	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
+#endif
 #define __get_cpu_var(var) \
 	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))
 #define __raw_get_cpu_var(var) \

lib/Kconfig.debug +12 -0

@@ -610,6 +610,18 @@ config PROVIDE_OHCI1394_DMA_INIT
 
 	  See Documentation/debugging-via-ohci1394.txt for more information.
 
+config DEBUG_PER_CPU
+	bool "Debug per_cpu usage"
+	depends on DEBUG_KERNEL
+	depends on SMP
+	default n
+	help
+	  Say Y here to add code that verifies the per_cpu area is
+	  setup before accessing a per_cpu variable.  It does add a
+	  significant amount of code to kernel memory.
+
+	  If unsure, say N.
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"

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Ingo Molnar

2008-01-18 20:39 UTC #11 lore raw

In reply to [email protected]

Quoted 9 lines · * [email protected] <[email protected]> wrote:

This patchset simplifies the code that arches need to maintain to support per cpu functionality. Most of the code is moved into arch independent code. Only a minimal set of definitions is kept for each arch.
The patch also unifies the x86 arch so that there is only a single asm-x86/percpu.h
Based on: 2.6.24-rc8-mm1

just to make sure i got it right: due to the multi-arch scope of this patchset, this is for -mm, right?

Ingo

Mike Travis

author

2008-01-18 20:51 UTC #12 lore raw

Quoted 10 lines · Ingo Molnar

Quoted 8 lines · * [email protected] <[email protected]> wrote:
This patchset simplifies the code that arches need to maintain to support per cpu functionality. Most of the code is moved into arch independent code. Only a minimal set of definitions is kept for each arch.
The patch also unifies the x86 arch so that there is only a single asm-x86/percpu.h

Quoted 6 lines

Quoted 1 line
Based on: 2.6.24-rc8-mm1
just to make sure i got it right: due to the multi-arch scope of this patchset, this is for -mm, right?
Ingo

Yes, it is.

Thanks,
Mike