From e74e396204bfcb67570ba4517b08f5918e69afea Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 30 Mar 2009 19:07:44 +0900 Subject: percpu: use dynamic percpu allocator as the default percpu allocator This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo Acked-by: Rusty Russell Acked-by: David S. Miller Acked-by: Benjamin Herrenschmidt Acked-by: Martin Schwidefsky Reviewed-by: Christoph Lameter Cc: Paul Mundt Cc: Russell King Cc: Mikael Starvik Cc: Ralf Baechle Cc: Bryan Wu Cc: Kyle McMartin Cc: Matthew Wilcox Cc: Grant Grundler Cc: Hirokazu Takata Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Heiko Carstens Cc: Ingo Molnar --- arch/s390/Kconfig | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/s390') diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index a14dba0e4d67..f4a3cc62d28f 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -75,6 +75,9 @@ config VIRT_CPU_ACCOUNTING config ARCH_SUPPORTS_DEBUG_PAGEALLOC def_bool y +config HAVE_LEGACY_PER_CPU_AREA + def_bool y + mainmenu "Linux Kernel Configuration" config S390 -- cgit v1.2.2 From 405d967dc70002991f8fc35c20e0d3cbc7614f63 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Jun 2009 15:13:38 +0900 Subject: linker script: throw away .discard section x86 throws away .discard section but no other archs do. Also, .discard is not thrown away while linking modules. Make every arch and module linking throw it away. This will be used to define dummy variables for percpu declarations and definitions. This patch is based on Ivan Kokshaysky's alpha percpu patch. [ Impact: always throw away everything in .discard ] Signed-off-by: Tejun Heo Cc: Ivan Kokshaysky Cc: Richard Henderson Cc: Russell King Cc: Haavard Skinnemoen Cc: Bryan Wu Cc: Mikael Starvik Cc: Jesper Nilsson Cc: David Howells Cc: Yoshinori Sato Cc: Tony Luck Cc: Hirokazu Takata Cc: Geert Uytterhoeven Cc: Michal Simek Cc: Ralf Baechle Cc: Kyle McMartin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Paul Mundt Cc: David S. Miller Cc: Jeff Dike Cc: Chris Zankel Cc: Rusty Russell Cc: Ingo Molnar --- arch/s390/kernel/vmlinux.lds.S | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/s390') diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index a53db23ee092..98867dfea469 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -161,6 +161,7 @@ SECTIONS /DISCARD/ : { EXIT_DATA *(.exitcall.exit) + *(.discard) } /* Debugging sections. */ -- cgit v1.2.2 From 9a0ef2923abd2cc2c6f78d3663ac7af34c0220e8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Jun 2009 15:13:53 +0900 Subject: s390: switch to dynamic percpu allocator 64bit s390 shares the same problem with alpha regarding percpu symbol addressing from modules. It needs assembly magic to force GOTENT reference when building module as the percpu address will be outside the usual 4G range from the module text. This can be solved by using weak percpu variable definitions. This patch makes s390 use weak definitions and switch to dynamic percpu allocator. Please note that weak attribute is not added if !SMP as percpu variables behave exactly the same as normal variables on UP. Compile tested. Generation of GOTENT reference verified. This patch is based on Ivan Kokshaysky's alpha percpu patch. [ Impact: use dynamic percpu allocator ] Signed-off-by: Tejun Heo Cc: Martin Schwidefsky Cc: Heiko Carstens --- arch/s390/Kconfig | 3 --- arch/s390/include/asm/percpu.h | 32 ++++++++------------------------ 2 files changed, 8 insertions(+), 27 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index f4a3cc62d28f..a14dba0e4d67 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -75,9 +75,6 @@ config VIRT_CPU_ACCOUNTING config ARCH_SUPPORTS_DEBUG_PAGEALLOC def_bool y -config HAVE_LEGACY_PER_CPU_AREA - def_bool y - mainmenu "Linux Kernel Configuration" config S390 diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 408d60b4f75b..f7ad8719d02d 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -1,37 +1,21 @@ #ifndef __ARCH_S390_PERCPU__ #define __ARCH_S390_PERCPU__ -#include -#include - /* * s390 uses its own implementation for per cpu data, the offset of * the cpu local data area is cached in the cpu's lowcore memory. - * For 64 bit module code s390 forces the use of a GOT slot for the - * address of the per cpu variable. This is needed because the module - * may be more than 4G above the per cpu area. */ -#if defined(__s390x__) && defined(MODULE) - -#define SHIFT_PERCPU_PTR(ptr,offset) (({ \ - extern int simple_identifier_##var(void); \ - unsigned long *__ptr; \ - asm ( "larl %0, %1@GOTENT" \ - : "=a" (__ptr) : "X" (ptr) ); \ - (typeof(ptr))((*__ptr) + (offset)); })) - -#else - -#define SHIFT_PERCPU_PTR(ptr, offset) (({ \ - extern int simple_identifier_##var(void); \ - unsigned long __ptr; \ - asm ( "" : "=a" (__ptr) : "0" (ptr) ); \ - (typeof(ptr)) (__ptr + (offset)); })) +#define __my_cpu_offset S390_lowcore.percpu_offset +/* + * For 64 bit module code, the module may be more than 4G above the + * per cpu area, use weak definitions to force the compiler to + * generate external references. + */ +#if defined(CONFIG_SMP) && defined(__s390x__) && defined(MODULE) +#define ARCH_NEEDS_WEAK_PER_CPU #endif -#define __my_cpu_offset S390_lowcore.percpu_offset - #include #endif /* __ARCH_S390_PERCPU__ */ -- cgit v1.2.2 From 023bf6f1b8bf58dc4da7f0dc1cf4787b0d5297c1 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 9 Jul 2009 11:27:40 +0900 Subject: linker script: unify usage of discard definition Discarded sections in different archs share some commonality but have considerable differences. This led to linker script for each arch implementing its own /DISCARD/ definition, which makes maintaining tedious and adding new entries error-prone. This patch makes all linker scripts to move discard definitions to the end of the linker script and use the common DISCARDS macro. As ld uses the first matching section definition, archs can include default discarded sections by including them earlier in the linker script. ia64 is notable because it first throws away some ia64 specific subsections and then include the rest of the sections into the final image, so those sections must be discarded before the inclusion. defconfig compile tested for x86, x86-64, powerpc, powerpc64, ia64, alpha, sparc, sparc64 and s390. Michal Simek tested microblaze. Signed-off-by: Tejun Heo Acked-by: Paul Mundt Acked-by: Mike Frysinger Tested-by: Michal Simek Cc: linux-arch@vger.kernel.org Cc: Michal Simek Cc: microblaze-uclinux@itee.uq.edu.au Cc: Sam Ravnborg Cc: Tony Luck --- arch/s390/kernel/vmlinux.lds.S | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index 98867dfea469..82415c75b996 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -157,14 +157,10 @@ SECTIONS _end = . ; - /* Sections to be discarded */ - /DISCARD/ : { - EXIT_DATA - *(.exitcall.exit) - *(.discard) - } - /* Debugging sections. */ STABS_DEBUG DWARF_DEBUG + + /* Sections to be discarded */ + DISCARDS } -- cgit v1.2.2