Subject: Re: [PATCH net-next 1/2] tools: add missing infrastructure for building ptr_ring.h

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 5 Jul 2021 14:39:23 -0400

On Mon, Jul 05, 2021 at 11:57:34AM +0800, Yunsheng Lin wrote:
> In order to build ptr_ring.h in userspace, the cacheline
> aligning, cpu_relax() and slab related infrastructure is
> needed, so add them in this patch.
> 
> As L1_CACHE_BYTES may be different for different arch, which
> is mostly defined in include/generated/autoconf.h, so user may
> need to do "make defconfig" before building a tool using the
> API in linux/cache.h.
> 
> Also "linux/lockdep.h" is not added in "tools/include" yet,
> so remove it in "linux/spinlock.h", and the only place using
> "linux/spinlock.h" is tools/testing/radix-tree, removing that
> does not break radix-tree testing.
> 
> Signed-off-by: Yunsheng Lin <[email-masked]>

This is hard to review.
Try to split this please. Functional changes separate from
merely moving code around.

> ---
>  tools/include/asm/cache.h          | 56 ++++++++++++++++++++++++
>  tools/include/asm/processor.h      | 36 ++++++++++++++++
>  tools/include/generated/autoconf.h |  1 +
>  tools/include/linux/align.h        | 15 +++++++
>  tools/include/linux/cache.h        | 87 ++++++++++++++++++++++++++++++++++++++
>  tools/include/linux/gfp.h          |  4 ++
>  tools/include/linux/slab.h         | 46 ++++++++++++++++++++
>  tools/include/linux/spinlock.h     |  2 -
>  8 files changed, 245 insertions(+), 2 deletions(-)
>  create mode 100644 tools/include/asm/cache.h
>  create mode 100644 tools/include/asm/processor.h
>  create mode 100644 tools/include/generated/autoconf.h
>  create mode 100644 tools/include/linux/align.h
>  create mode 100644 tools/include/linux/cache.h
>  create mode 100644 tools/include/linux/slab.h
> 
> diff --git a/tools/include/asm/cache.h b/tools/include/asm/cache.h
> new file mode 100644
> index 0000000..071e310
> --- /dev/null
> +++ b/tools/include/asm/cache.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __TOOLS_LINUX_ASM_CACHE_H
> +#define __TOOLS_LINUX_ASM_CACHE_H
> +
> +#include <generated/autoconf.h>
> +
> +#if defined(__i386__) || defined(__x86_64__)
> +#define L1_CACHE_SHIFT	(CONFIG_X86_L1_CACHE_SHIFT)
> +#elif defined(__arm__)
> +#define L1_CACHE_SHIFT	(CONFIG_ARM_L1_CACHE_SHIFT)
> +#elif defined(__aarch64__)
> +#define L1_CACHE_SHIFT	(6)
> +#elif defined(__powerpc__)
> +
> +/* bytes per L1 cache line */
> +#if defined(CONFIG_PPC_8xx)
> +#define L1_CACHE_SHIFT	4
> +#elif defined(CONFIG_PPC_E500MC)
> +#define L1_CACHE_SHIFT	6
> +#elif defined(CONFIG_PPC32)
> +#if defined(CONFIG_PPC_47x)
> +#define L1_CACHE_SHIFT	7
> +#else
> +#define L1_CACHE_SHIFT	5
> +#endif
> +#else /* CONFIG_PPC64 */
> +#define L1_CACHE_SHIFT	7
> +#endif
> +
> +#elif defined(__sparc__)
> +#define L1_CACHE_SHIFT 5
> +#elif defined(__alpha__)
> +
> +#if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_EV6)
> +#define L1_CACHE_SHIFT	6
> +#else
> +/* Both EV4 and EV5 are write-through, read-allocate,
> +   direct-mapped, physical.
> +*/
> +#define L1_CACHE_SHIFT	5
> +#endif
> +
> +#elif defined(__mips__)
> +#define L1_CACHE_SHIFT	CONFIG_MIPS_L1_CACHE_SHIFT
> +#elif defined(__ia64__)
> +#define L1_CACHE_SHIFT	CONFIG_IA64_L1_CACHE_SHIFT
> +#elif defined(__nds32__)
> +#define L1_CACHE_SHIFT	5
> +#else
> +#define L1_CACHE_SHIFT	5
> +#endif
> +
> +#define L1_CACHE_BYTES	(1 << L1_CACHE_SHIFT)
> +
> +#endif
> diff --git a/tools/include/asm/processor.h b/tools/include/asm/processor.h
> new file mode 100644
> index 0000000..3198ad6
> --- /dev/null
> +++ b/tools/include/asm/processor.h
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __TOOLS_LINUX_ASM_PROCESSOR_H
> +#define __TOOLS_LINUX_ASM_PROCESSOR_H
> +
> +#include <pthread.h>
> +
> +#if defined(__i386__) || defined(__x86_64__)
> +#include "../../arch/x86/include/asm/vdso/processor.h"
> +#elif defined(__arm__)
> +#include "../../arch/arm/include/asm/vdso/processor.h"
> +#elif defined(__aarch64__)
> +#include "../../arch/arm64/include/asm/vdso/processor.h"
> +#elif defined(__powerpc__)
> +#include "../../arch/powerpc/include/vdso/processor.h"
> +#elif defined(__s390__)
> +#include "../../arch/s390/include/vdso/processor.h"
> +#elif defined(__sh__)
> +#include "../../arch/sh/include/asm/processor.h"
> +#elif defined(__sparc__)
> +#include "../../arch/sparc/include/asm/processor.h"
> +#elif defined(__alpha__)
> +#include "../../arch/alpha/include/asm/processor.h"
> +#elif defined(__mips__)
> +#include "../../arch/mips/include/asm/vdso/processor.h"
> +#elif defined(__ia64__)
> +#include "../../arch/ia64/include/asm/processor.h"
> +#elif defined(__xtensa__)
> +#include "../../arch/xtensa/include/asm/processor.h"
> +#elif defined(__nds32__)
> +#include "../../arch/nds32/include/asm/processor.h"
> +#else
> +#define cpu_relax()	sched_yield()

Does this have a chance to work outside of kernel?

> +#endif

did you actually test or even test build all these arches?
Not sure we need to bother with hacks like these.

> +
> +#endif
> diff --git a/tools/include/generated/autoconf.h b/tools/include/generated/autoconf.h
> new file mode 100644
> index 0000000..c588a2f
> --- /dev/null
> +++ b/tools/include/generated/autoconf.h
> @@ -0,0 +1 @@
> +#include "../../../include/generated/autoconf.h"
> diff --git a/tools/include/linux/align.h b/tools/include/linux/align.h
> new file mode 100644
> index 0000000..4e82cdf
> --- /dev/null
> +++ b/tools/include/linux/align.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TOOLS_LINUX_ALIGN_H
> +#define __TOOLS_LINUX_ALIGN_H
> +
> +#include <linux/const.h>
> +
> +/* @a is a power of 2 value */
> +#define ALIGN(x, a)		__ALIGN_KERNEL((x), (a))
> +#define ALIGN_DOWN(x, a)	__ALIGN_KERNEL((x) - ((a) - 1), (a))
> +#define __ALIGN_MASK(x, mask)	__ALIGN_KERNEL_MASK((x), (mask))
> +#define PTR_ALIGN(p, a)		((typeof(p))ALIGN((unsigned long)(p), (a)))
> +#define PTR_ALIGN_DOWN(p, a)	((typeof(p))ALIGN_DOWN((unsigned long)(p), (a)))
> +#define IS_ALIGNED(x, a)		(((x) & ((typeof(x))(a) - 1)) == 0)
> +
> +#endif	/* _LINUX_ALIGN_H */
> diff --git a/tools/include/linux/cache.h b/tools/include/linux/cache.h
> new file mode 100644
> index 0000000..8f86b1b
> --- /dev/null
> +++ b/tools/include/linux/cache.h
> @@ -0,0 +1,87 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TOOLS_LINUX__CACHE_H
> +#define __TOOLS_LINUX__CACHE_H
> +
> +#include <asm/cache.h>
> +
> +#ifndef L1_CACHE_ALIGN
> +#define L1_CACHE_ALIGN(x) __ALIGN_KERNEL(x, L1_CACHE_BYTES)
> +#endif
> +
> +#ifndef SMP_CACHE_BYTES
> +#define SMP_CACHE_BYTES L1_CACHE_BYTES
> +#endif
> +
> +/*
> + * __read_mostly is used to keep rarely changing variables out of frequently
> + * updated cachelines. Its use should be reserved for data that is used
> + * frequently in hot paths. Performance traces can help decide when to use
> + * this. You want __read_mostly data to be tightly packed, so that in the
> + * best case multiple frequently read variables for a hot path will be next
> + * to each other in order to reduce the number of cachelines needed to
> + * execute a critical path. We should be mindful and selective of its use.
> + * ie: if you're going to use it please supply a *good* justification in your
> + * commit log
> + */
> +#ifndef __read_mostly
> +#define __read_mostly
> +#endif
> +
> +/*
> + * __ro_after_init is used to mark things that are read-only after init (i.e.
> + * after mark_rodata_ro() has been called). These are effectively read-only,
> + * but may get written to during init, so can't live in .rodata (via "const").
> + */
> +#ifndef __ro_after_init
> +#define __ro_after_init __section(".data..ro_after_init")
> +#endif
> +
> +#ifndef ____cacheline_aligned
> +#define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
> +#endif
> +
> +#ifndef ____cacheline_aligned_in_smp
> +#ifdef CONFIG_SMP
> +#define ____cacheline_aligned_in_smp ____cacheline_aligned
> +#else
> +#define ____cacheline_aligned_in_smp
> +#endif /* CONFIG_SMP */
> +#endif
> +
> +#ifndef __cacheline_aligned
> +#define __cacheline_aligned					\
> +  __attribute__((__aligned__(SMP_CACHE_BYTES),			\
> +		 __section__(".data..cacheline_aligned")))
> +#endif /* __cacheline_aligned */
> +
> +#ifndef __cacheline_aligned_in_smp
> +#ifdef CONFIG_SMP
> +#define __cacheline_aligned_in_smp __cacheline_aligned
> +#else
> +#define __cacheline_aligned_in_smp
> +#endif /* CONFIG_SMP */
> +#endif
> +
> +/*
> + * The maximum alignment needed for some critical structures
> + * These could be inter-node cacheline sizes/L3 cacheline
> + * size etc.  Define this in asm/cache.h for your arch
> + */
> +#ifndef INTERNODE_CACHE_SHIFT
> +#define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT
> +#endif
> +
> +#if !defined(____cacheline_internodealigned_in_smp)
> +#if defined(CONFIG_SMP)
> +#define ____cacheline_internodealigned_in_smp \
> +	__attribute__((__aligned__(1 << (INTERNODE_CACHE_SHIFT))))
> +#else
> +#define ____cacheline_internodealigned_in_smp
> +#endif
> +#endif
> +
> +#ifndef CONFIG_ARCH_HAS_CACHE_LINE_SIZE
> +#define cache_line_size()	L1_CACHE_BYTES
> +#endif
> +
> +#endif /* __LINUX_CACHE_H */
> diff --git a/tools/include/linux/gfp.h b/tools/include/linux/gfp.h
> index 2203075..d7041c0 100644
> --- a/tools/include/linux/gfp.h
> +++ b/tools/include/linux/gfp.h
> @@ -1,4 +1,8 @@
>  #ifndef _TOOLS_INCLUDE_LINUX_GFP_H
>  #define _TOOLS_INCLUDE_LINUX_GFP_H
>  
> +#include <linux/types.h>
> +
> +#define __GFP_ZERO		0x100u
> +
>  #endif /* _TOOLS_INCLUDE_LINUX_GFP_H */
> diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h
> new file mode 100644
> index 0000000..f0b7da6
> --- /dev/null
> +++ b/tools/include/linux/slab.h
> @@ -0,0 +1,46 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TOOLS_LINUX_SLAB_H
> +#define __TOOLS_LINUX_SLAB_H
> +
> +#include <linux/gfp.h>
> +#include <linux/cache.h>
> +
> +static inline void *kmalloc(size_t size, gfp_t gfp)
> +{
> +	void *p;
> +
> +	p = memalign(SMP_CACHE_BYTES, size);
> +	if (!p)
> +		return p;
> +
> +	if (gfp & __GFP_ZERO)
> +		memset(p, 0, size);
> +
> +	return p;
> +}
> +
> +static inline void *kzalloc(size_t size, gfp_t flags)
> +{
> +	return kmalloc(size, flags | __GFP_ZERO);
> +}
> +
> +static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
> +{
> +	return kmalloc(n * size, flags);
> +}
> +
> +static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
> +{
> +	return kmalloc_array(n, size, flags | __GFP_ZERO);
> +}
> +
> +static inline void kfree(void *p)
> +{
> +	free(p);
> +}
> +
> +#define kvmalloc_array		kmalloc_array
> +#define kvfree			kfree
> +#define KMALLOC_MAX_SIZE	SIZE_MAX
> +
> +#endif
> diff --git a/tools/include/linux/spinlock.h b/tools/include/linux/spinlock.h
> index c934572..622266b 100644
> --- a/tools/include/linux/spinlock.h
> +++ b/tools/include/linux/spinlock.h
> @@ -37,6 +37,4 @@ static inline bool arch_spin_is_locked(arch_spinlock_t *mutex)
>  	return true;
>  }
>  
> -#include <linux/lockdep.h>
> -
>  #endif
> -- 
> 2.7.4