* [PATCH 1/2] bug.h: Introduce HAVE_ARCH_WARN @ 2007-10-11 17:12 Olof Johansson 2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson 0 siblings, 1 reply; 8+ messages in thread From: Olof Johansson @ 2007-10-11 17:12 UTC (permalink / raw) To: linux-kernel; +Cc: akpm, lethal, grundler, kyle HAVE_ARCH_WARN is used to determine if an arch already has a __WARN() macro, or if a generic one is needed. With this, some of the arch-specific WARN_ON() implementations can be made common instead (see follow-up patch for powerpc). Signed-off-by: Olof Johansson <olof@lixom.net> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index d56fedb..c6b8386 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -31,14 +31,19 @@ struct bug_entry { #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while(0) #endif +#ifndef HAVE_ARCH_WARN +#define __WARN() do { \ + printk("WARNING: at %s:%d %s()\n", __FILE__, \ + __LINE__, __FUNCTION__); \ + dump_stack(); \ +} while (0) +#endif + #ifndef HAVE_ARCH_WARN_ON #define WARN_ON(condition) ({ \ int __ret_warn_on = !!(condition); \ - if (unlikely(__ret_warn_on)) { \ - printk("WARNING: at %s:%d %s()\n", __FILE__, \ - __LINE__, __FUNCTION__); \ - dump_stack(); \ - } \ + if (unlikely(__ret_warn_on)) \ + __WARN(); \ unlikely(__ret_warn_on); \ }) #endif diff --git a/include/asm-parisc/bug.h b/include/asm-parisc/bug.h index 8cfc553..3f68100 100644 --- a/include/asm-parisc/bug.h +++ b/include/asm-parisc/bug.h @@ -8,6 +8,7 @@ #ifdef CONFIG_BUG #define HAVE_ARCH_BUG +#define HAVE_ARCH_WARN #define HAVE_ARCH_WARN_ON /* the break instruction is used as BUG() marker. */ diff --git a/include/asm-powerpc/bug.h b/include/asm-powerpc/bug.h index e55d1f6..02e171c 100644 --- a/include/asm-powerpc/bug.h +++ b/include/asm-powerpc/bug.h @@ -110,6 +110,7 @@ }) #define HAVE_ARCH_BUG +#define HAVE_ARCH_WARN #define HAVE_ARCH_BUG_ON #define HAVE_ARCH_WARN_ON #endif /* __ASSEMBLY __ */ diff --git a/include/asm-sh/bug.h b/include/asm-sh/bug.h index a78d482..4ea415b 100644 --- a/include/asm-sh/bug.h +++ b/include/asm-sh/bug.h @@ -5,6 +5,7 @@ #ifdef CONFIG_BUG #define HAVE_ARCH_BUG +#define HAVE_ARCH_WARN #define HAVE_ARCH_WARN_ON /** ^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-11 17:12 [PATCH 1/2] bug.h: Introduce HAVE_ARCH_WARN Olof Johansson @ 2007-10-11 17:14 ` Olof Johansson 2007-10-11 19:55 ` Scott Wood ` (2 more replies) 0 siblings, 3 replies; 8+ messages in thread From: Olof Johansson @ 2007-10-11 17:14 UTC (permalink / raw) To: linux-kernel; +Cc: grundler, kyle, linuxppc-dev, lethal, akpm Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about 4K text on a ppc64_defconfig. The main reason seems to be that prepping the arguments to the conditional trap instructions is more work than just doing a compare and branch. Signed-off-by: Olof Johansson <olof@lixom.net> diff --git a/include/asm-powerpc/bug.h b/include/asm-powerpc/bug.h index 02e171c..966de9b 100644 --- a/include/asm-powerpc/bug.h +++ b/include/asm-powerpc/bug.h @@ -54,12 +54,6 @@ ".previous\n" #endif -/* - * BUG_ON() and WARN_ON() do their best to cooperate with compile-time - * optimisations. However depending on the complexity of the condition - * some compiler versions may not produce optimal results. - */ - #define BUG() do { \ __asm__ __volatile__( \ "1: twi 31,0,0\n" \ @@ -69,20 +63,6 @@ for(;;) ; \ } while (0) -#define BUG_ON(x) do { \ - if (__builtin_constant_p(x)) { \ - if (x) \ - BUG(); \ - } else { \ - __asm__ __volatile__( \ - "1: "PPC_TLNEI" %4,0\n" \ - _EMIT_BUG_ENTRY \ - : : "i" (__FILE__), "i" (__LINE__), "i" (0), \ - "i" (sizeof(struct bug_entry)), \ - "r" ((__force long)(x))); \ - } \ -} while (0) - #define __WARN() do { \ __asm__ __volatile__( \ "1: twi 31,0,0\n" \ @@ -92,27 +72,8 @@ "i" (sizeof(struct bug_entry))); \ } while (0) -#define WARN_ON(x) ({ \ - int __ret_warn_on = !!(x); \ - if (__builtin_constant_p(__ret_warn_on)) { \ - if (__ret_warn_on) \ - __WARN(); \ - } else { \ - __asm__ __volatile__( \ - "1: "PPC_TLNEI" %4,0\n" \ - _EMIT_BUG_ENTRY \ - : : "i" (__FILE__), "i" (__LINE__), \ - "i" (BUGFLAG_WARNING), \ - "i" (sizeof(struct bug_entry)), \ - "r" (__ret_warn_on)); \ - } \ - unlikely(__ret_warn_on); \ -}) - #define HAVE_ARCH_BUG #define HAVE_ARCH_WARN -#define HAVE_ARCH_BUG_ON -#define HAVE_ARCH_WARN_ON #endif /* __ASSEMBLY __ */ #endif /* CONFIG_BUG */ ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson @ 2007-10-11 19:55 ` Scott Wood 2007-10-12 1:23 ` Paul Mackerras 2007-10-19 2:03 ` [PATCH v2] [2/2] " Olof Johansson 2 siblings, 0 replies; 8+ messages in thread From: Scott Wood @ 2007-10-11 19:55 UTC (permalink / raw) To: Olof Johansson; +Cc: grundler, linux-kernel, kyle, linuxppc-dev, lethal, akpm On Thu, Oct 11, 2007 at 12:14:13PM -0500, Olof Johansson wrote: > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about > 4K text on a ppc64_defconfig. The main reason seems to be that prepping > the arguments to the conditional trap instructions is more work than > just doing a compare and branch. It'd be nice if we could get GCC to generate bug table entries for __builtin_trap(); that way we could use GCC's ability to put arbitrary conditions in the trap instruction. -Scott ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson 2007-10-11 19:55 ` Scott Wood @ 2007-10-12 1:23 ` Paul Mackerras 2007-10-12 2:04 ` Kyle McMartin 2007-10-12 2:40 ` Olof Johansson 2007-10-19 2:03 ` [PATCH v2] [2/2] " Olof Johansson 2 siblings, 2 replies; 8+ messages in thread From: Paul Mackerras @ 2007-10-12 1:23 UTC (permalink / raw) To: Olof Johansson; +Cc: grundler, linux-kernel, kyle, linuxppc-dev, lethal, akpm Olof Johansson writes: > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about > 4K text on a ppc64_defconfig. The main reason seems to be that prepping > the arguments to the conditional trap instructions is more work than > just doing a compare and branch. It might be more instructions but it takes fewer cycles, I would expect. Do you have the actual instruction sequences to compare? Paul. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-12 1:23 ` Paul Mackerras @ 2007-10-12 2:04 ` Kyle McMartin 2007-10-12 2:41 ` Olof Johansson 2007-10-12 2:40 ` Olof Johansson 1 sibling, 1 reply; 8+ messages in thread From: Kyle McMartin @ 2007-10-12 2:04 UTC (permalink / raw) To: Paul Mackerras Cc: grundler, linux-kernel, kyle, linuxppc-dev, lethal, Olof Johansson, akpm On Fri, Oct 12, 2007 at 11:23:39AM +1000, Paul Mackerras wrote: > Olof Johansson writes: > > > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about > > 4K text on a ppc64_defconfig. The main reason seems to be that prepping > > the arguments to the conditional trap instructions is more work than > > just doing a compare and branch. > > It might be more instructions but it takes fewer cycles, I would > expect. Do you have the actual instruction sequences to compare? > I really hope WARN_ON/BUG_ON aren't hotpaths on powerpc. ;-) Cheers, Kyle ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-12 2:04 ` Kyle McMartin @ 2007-10-12 2:41 ` Olof Johansson 0 siblings, 0 replies; 8+ messages in thread From: Olof Johansson @ 2007-10-12 2:41 UTC (permalink / raw) To: Kyle McMartin Cc: grundler, linux-kernel, kyle, linuxppc-dev, lethal, Paul Mackerras, akpm On Thu, Oct 11, 2007 at 10:04:19PM -0400, Kyle McMartin wrote: > On Fri, Oct 12, 2007 at 11:23:39AM +1000, Paul Mackerras wrote: > > Olof Johansson writes: > > > > > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about > > > 4K text on a ppc64_defconfig. The main reason seems to be that prepping > > > the arguments to the conditional trap instructions is more work than > > > just doing a compare and branch. > > > > It might be more instructions but it takes fewer cycles, I would > > expect. Do you have the actual instruction sequences to compare? > > > > I really hope WARN_ON/BUG_ON aren't hotpaths on powerpc. ;-) Not the taken branch of them, no. :) But making it past them as fast as possible when they're not tripping is always good. -Olof ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-12 1:23 ` Paul Mackerras 2007-10-12 2:04 ` Kyle McMartin @ 2007-10-12 2:40 ` Olof Johansson 1 sibling, 0 replies; 8+ messages in thread From: Olof Johansson @ 2007-10-12 2:40 UTC (permalink / raw) To: Paul Mackerras; +Cc: grundler, linux-kernel, kyle, linuxppc-dev, lethal, akpm On Fri, Oct 12, 2007 at 11:23:39AM +1000, Paul Mackerras wrote: > Olof Johansson writes: > > > Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about > > 4K text on a ppc64_defconfig. The main reason seems to be that prepping > > the arguments to the conditional trap instructions is more work than > > just doing a compare and branch. > > It might be more instructions but it takes fewer cycles, I would > expect. Do you have the actual instruction sequences to compare? Sure. Just looking at a couple of cases: On range comparisons such as (a < CONST): * without this patch, you end up with a comparison, then a cr-to-cr op + mfcr + mask operation + tdnei. * with the patch, you get a comparison and a conditional branch with twi out of line. On multiple comparisons like WARN_ON( a || b), it seems that there's an added li to make the tdnei always hit for the first case. There it uses a regular conditional branch, so no real difference in generated code besides that. Code examples. This was with a ppc64_defconfig, so CONFIG_POWER4_ONLY wasn't enabled. It uses mfocrf when it is, which is alot cheaper. Still, the rest of the code sequence is the same: void irq_free_virt(unsigned int virq, unsigned int count) { unsigned long flags; unsigned int i; WARN_ON (virq < NUM_ISA_INTERRUPTS); WARN_ON (count == 0 || (virq + count) > irq_virq_count); spin_lock_irqsave(&irq_big_lock, flags); Without the patch: c00000000000b33c <.irq_free_virt>: c00000000000b33c: 7c 08 02 a6 mflr r0 c00000000000b340: 2b 83 00 0f cmplwi cr7,r3,15 c00000000000b344: fb c1 ff f0 std r30,-16(r1) c00000000000b348: fb e1 ff f8 std r31,-8(r1) c00000000000b34c: 7c 9e 23 78 mr r30,r4 c00000000000b350: 7c 7f 1b 78 mr r31,r3 c00000000000b354: 4f dd e8 42 crnot 4*cr7+eq,4*cr7+gt c00000000000b358: f8 01 00 10 std r0,16(r1) c00000000000b35c: f8 21 ff 81 stdu r1,-128(r1) c00000000000b360: 7c 00 00 26 mfcr r0 c00000000000b364: 54 00 ff fe rlwinm r0,r0,31,31,31 c00000000000b368: 0b 00 00 00 tdnei r0,0 c00000000000b36c: 2f a4 00 00 cmpdi cr7,r4,0 c00000000000b370: 38 00 00 01 li r0,1 c00000000000b374: 41 9e 00 1c beq cr7,c00000000000b390 <.irq_free_virt+0x54> c00000000000b378: e9 22 80 d8 ld r9,-32552(r2) c00000000000b37c: 7d 63 22 14 add r11,r3,r4 c00000000000b380: 80 09 00 00 lwz r0,0(r9) c00000000000b384: 7f 8b 00 40 cmplw cr7,r11,r0 c00000000000b388: 7c 00 00 26 mfcr r0 c00000000000b38c: 54 00 f7 fe rlwinm r0,r0,30,31,31 c00000000000b390: 0b 00 00 00 tdnei r0,0 c00000000000b394: e8 62 80 f8 ld r3,-32520(r2) c00000000000b398: 48 54 4c b1 bl c000000000550048 <._spin_lock_irqsave> c00000000000b39c: 60 00 00 00 nop With the patch: c00000000000b0b0 <.irq_free_virt>: c00000000000b0b0: 7c 08 02 a6 mflr r0 c00000000000b0b4: 2b 83 00 0f cmplwi cr7,r3,15 c00000000000b0b8: fb c1 ff f0 std r30,-16(r1) c00000000000b0bc: fb e1 ff f8 std r31,-8(r1) c00000000000b0c0: 7c 9e 23 78 mr r30,r4 c00000000000b0c4: 7c 7f 1b 78 mr r31,r3 c00000000000b0c8: f8 01 00 10 std r0,16(r1) c00000000000b0cc: f8 21 ff 81 stdu r1,-128(r1) c00000000000b0d0: 41 bd 00 08 bgt cr7,c00000000000b0d8 <.irq_free_virt+0x28> c00000000000b0d4: 0f e0 00 00 twi 31,r0,0 c00000000000b0d8: 2f be 00 00 cmpdi cr7,r30,0 c00000000000b0dc: 41 9e 00 18 beq cr7,c00000000000b0f4 <.irq_free_virt+0x44> c00000000000b0e0: e9 22 80 d8 ld r9,-32552(r2) c00000000000b0e4: 7d 7f f2 14 add r11,r31,r30 c00000000000b0e8: 80 09 00 00 lwz r0,0(r9) c00000000000b0ec: 7f 8b 00 40 cmplw cr7,r11,r0 c00000000000b0f0: 40 bd 00 08 ble cr7,c00000000000b0f8 <.irq_free_virt+0x48> c00000000000b0f4: 0f e0 00 00 twi 31,r0,0 c00000000000b0f8: e8 62 80 f8 ld r3,-32520(r2) c00000000000b0fc: 48 54 3f 75 bl c00000000054f070 <._spin_lock_irqsave> c00000000000b100: 60 00 00 00 nop ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2] [2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() 2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson 2007-10-11 19:55 ` Scott Wood 2007-10-12 1:23 ` Paul Mackerras @ 2007-10-19 2:03 ` Olof Johansson 2 siblings, 0 replies; 8+ messages in thread From: Olof Johansson @ 2007-10-19 2:03 UTC (permalink / raw) To: linux-kernel; +Cc: grundler, kyle, linuxppc-dev, lethal, akpm [POWERPC] Switch to generic WARN_ON()/BUG_ON() Not using the ppc-specific WARN_ON/BUG_ON constructs actually saves about 4K text on a ppc64_defconfig. The main reason seems to be that prepping the arguments to the conditional trap instructions is more work than just doing a compare and branch. Signed-off-by: Olof Johansson <olof@lixom.net> Index: k.org/include/asm-powerpc/bug.h =================================================================== --- k.org.orig/include/asm-powerpc/bug.h +++ k.org/include/asm-powerpc/bug.h @@ -54,12 +54,6 @@ ".previous\n" #endif -/* - * BUG_ON() and WARN_ON() do their best to cooperate with compile-time - * optimisations. However depending on the complexity of the condition - * some compiler versions may not produce optimal results. - */ - #define BUG() do { \ __asm__ __volatile__( \ "1: twi 31,0,0\n" \ @@ -69,20 +63,6 @@ for(;;) ; \ } while (0) -#define BUG_ON(x) do { \ - if (__builtin_constant_p(x)) { \ - if (x) \ - BUG(); \ - } else { \ - __asm__ __volatile__( \ - "1: "PPC_TLNEI" %4,0\n" \ - _EMIT_BUG_ENTRY \ - : : "i" (__FILE__), "i" (__LINE__), "i" (0), \ - "i" (sizeof(struct bug_entry)), \ - "r" ((__force long)(x))); \ - } \ -} while (0) - #define __WARN() do { \ __asm__ __volatile__( \ "1: twi 31,0,0\n" \ @@ -92,23 +72,6 @@ "i" (sizeof(struct bug_entry))); \ } while (0) -#define WARN_ON(x) ({ \ - int __ret_warn_on = !!(x); \ - if (__builtin_constant_p(__ret_warn_on)) { \ - if (__ret_warn_on) \ - __WARN(); \ - } else { \ - __asm__ __volatile__( \ - "1: "PPC_TLNEI" %4,0\n" \ - _EMIT_BUG_ENTRY \ - : : "i" (__FILE__), "i" (__LINE__), \ - "i" (BUGFLAG_WARNING), \ - "i" (sizeof(struct bug_entry)), \ - "r" (__ret_warn_on)); \ - } \ - unlikely(__ret_warn_on); \ -}) - #endif /* __ASSEMBLY __ */ #endif /* CONFIG_BUG */ ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2007-10-19 2:03 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2007-10-11 17:12 [PATCH 1/2] bug.h: Introduce HAVE_ARCH_WARN Olof Johansson 2007-10-11 17:14 ` [PATCH 2/2] powerpc: Switch to generic WARN_ON()/BUG_ON() Olof Johansson 2007-10-11 19:55 ` Scott Wood 2007-10-12 1:23 ` Paul Mackerras 2007-10-12 2:04 ` Kyle McMartin 2007-10-12 2:41 ` Olof Johansson 2007-10-12 2:40 ` Olof Johansson 2007-10-19 2:03 ` [PATCH v2] [2/2] " Olof Johansson
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