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

On Tue, Jul 06, 2021 at 10:04:02AM +0800, Yunsheng Lin wrote:

On 2021/7/6 2:39, Michael S. Tsirkin wrote:

quoted

On Mon, Jul 05, 2021 at 11:57:34AM +0800, Yunsheng Lin wrote:

quoted

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 <redacted>

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

Sure.

quoted

quoted

---
 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?

I am not sure I understand what you meant here.
sched_yield() is a pthread API, so it should work in the
user space.
And it allow the rigntest to compile when it is built on
the arch which is not handled as above.

It might compile but is likely too heavy to behave
reasonably.

Also, given you did not actually test it I don't
think you should add such arch code.
Note you broke at least s390 here:
../../arch/s390/include/vdso/processor.h
does not actually exist. Where these headers
do exit they tend to include lots of code which won't
build out of kernel.

All this is just for cpu_relax - open coding that seems way easier.

quoted

quoted

+#endif

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

Only x86_64 and arm64 arches have been built and tested.

In that case I think you should not add code that you
have not even built let alone tested.

This is added referring the tools/include/asm/barrier.h.

quoted

quoted

+