tools/testing/scatterlist: Test new __sg_alloc_table_from_pages

Exercise the new __sg_alloc_table_from_pages API (and through
it also the old sg_alloc_table_from_pages), checking that the
created table has the expected number of segments depending on
the sequence of input pages and other conditions.

v2: Move to data driven for readability.
v3: Add some more testcases and -fsanitize=undefined. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <[e-mail]>
Cc: Chris Wilson <[e-mail]>
Cc: [e-mail]
Reviewed-by: Chris Wilson <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
[tursulin: whitespace fixup]

tools/testing/scatterlist/Makefile

···
+CFLAGS += -I. -I../../include -g -O2 -Wall -fsanitize=address
+LDFLAGS += -fsanitize=address -fsanitize=undefined
+TARGETS = main
+OFILES = main.o scatterlist.o
+
+ifeq ($(BUILD), 32)
+        CFLAGS += -m32
+        LDFLAGS += -m32
+endif
+
+targets: include $(TARGETS)
+
+main: $(OFILES)
+
+clean:
+	$(RM) $(TARGETS) $(OFILES) scatterlist.c linux/scatterlist.h linux/highmem.h linux/kmemleak.h asm/io.h
+	@rmdir asm
+
+scatterlist.c: ../../../lib/scatterlist.c
+	@sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
+.PHONY: include
+
+include: ../../../include/linux/scatterlist.h
+	@mkdir -p linux
+	@mkdir -p asm
+	@touch asm/io.h
+	@touch linux/highmem.h
+	@touch linux/kmemleak.h
+	@cp $< linux/scatterlist.h

tools/testing/scatterlist/linux/mm.h

···
+#ifndef _LINUX_MM_H
+#define _LINUX_MM_H
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+
+typedef unsigned long dma_addr_t;
+
+#define unlikely
+
+#define BUG_ON(x) assert(!(x))
+
+#define WARN_ON(condition) ({                                           \
+	int __ret_warn_on = !!(condition);                              \
+	unlikely(__ret_warn_on);                                        \
+})
+
+#define WARN_ON_ONCE(condition) ({                              \
+	int __ret_warn_on = !!(condition);                      \
+	if (unlikely(__ret_warn_on))                            \
+		assert(0);                                      \
+	unlikely(__ret_warn_on);                                \
+})
+
+#define PAGE_SIZE	(4096)
+#define PAGE_SHIFT	(12)
+#define PAGE_MASK	(~(PAGE_SIZE-1))
+
+#define __ALIGN_KERNEL(x, a)		__ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
+#define __ALIGN_KERNEL_MASK(x, mask)	(((x) + (mask)) & ~(mask))
+#define ALIGN(x, a)			__ALIGN_KERNEL((x), (a))
+
+#define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
+
+#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
+
+#define virt_to_page(x)	((void *)x)
+#define page_address(x)	((void *)x)
+
+static inline unsigned long page_to_phys(struct page *page)
+{
+	assert(0);
+
+	return 0;
+}
+
+#define page_to_pfn(page) ((unsigned long)(page) / PAGE_SIZE)
+#define pfn_to_page(pfn) (void *)((pfn) * PAGE_SIZE)
+#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
+
+#define __min(t1, t2, min1, min2, x, y) ({              \
+	t1 min1 = (x);                                  \
+	t2 min2 = (y);                                  \
+	(void) (&min1 == &min2);                        \
+	min1 < min2 ? min1 : min2; })
+
+#define ___PASTE(a,b) a##b
+#define __PASTE(a,b) ___PASTE(a,b)
+
+#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+#define min(x, y)                                       \
+	__min(typeof(x), typeof(y),                     \
+	      __UNIQUE_ID(min1_), __UNIQUE_ID(min2_),   \
+	      x, y)
+
+#define min_t(type, x, y)                               \
+	__min(type, type,                               \
+	      __UNIQUE_ID(min1_), __UNIQUE_ID(min2_),   \
+	      x, y)
+
+#define preemptible() (1)
+
+static inline void *kmap(struct page *page)
+{
+	assert(0);
+
+	return NULL;
+}
+
+static inline void *kmap_atomic(struct page *page)
+{
+	assert(0);
+
+	return NULL;
+}
+
+static inline void kunmap(void *addr)
+{
+	assert(0);
+}
+
+static inline void kunmap_atomic(void *addr)
+{
+	assert(0);
+}
+
+static inline unsigned long __get_free_page(unsigned int flags)
+{
+	return (unsigned long)malloc(PAGE_SIZE);
+}
+
+static inline void free_page(unsigned long page)
+{
+	free((void *)page);
+}
+
+static inline void *kmalloc(unsigned int size, unsigned int flags)
+{
+	return malloc(size);
+}
+
+#define kfree(x) free(x)
+
+#define kmemleak_alloc(a, b, c, d)
+#define kmemleak_free(a)
+
+#define PageSlab(p) (0)
+#define flush_kernel_dcache_page(p)
+
+#endif

tools/testing/scatterlist/main.c

···
+#include <stdio.h>
+#include <assert.h>
+
+#include <linux/scatterlist.h>
+
+#define MAX_PAGES (64)
+
+static void set_pages(struct page **pages, const unsigned *array, unsigned num)
+{
+	unsigned int i;
+
+	assert(num < MAX_PAGES);
+	for (i = 0; i < num; i++)
+		pages[i] = (struct page *)(unsigned long)
+			   ((1 + array[i]) * PAGE_SIZE);
+}
+
+#define pfn(...) (unsigned []){ __VA_ARGS__ }
+
+int main(void)
+{
+	const unsigned int sgmax = SCATTERLIST_MAX_SEGMENT;
+	struct test {
+		int alloc_ret;
+		unsigned num_pages;
+		unsigned *pfn;
+		unsigned size;
+		unsigned int max_seg;
+		unsigned int expected_segments;
+	} *test, tests[] = {
+		{ -EINVAL, 1, pfn(0), PAGE_SIZE, PAGE_SIZE + 1, 1 },
+		{ -EINVAL, 1, pfn(0), PAGE_SIZE, 0, 1 },
+		{ -EINVAL, 1, pfn(0), PAGE_SIZE, sgmax + 1, 1 },
+		{ 0, 1, pfn(0), PAGE_SIZE, sgmax, 1 },
+		{ 0, 1, pfn(0), 1, sgmax, 1 },
+		{ 0, 2, pfn(0, 1), 2 * PAGE_SIZE, sgmax, 1 },
+		{ 0, 2, pfn(1, 0), 2 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 3, pfn(0, 1, 2), 3 * PAGE_SIZE, sgmax, 1 },
+		{ 0, 3, pfn(0, 2, 1), 3 * PAGE_SIZE, sgmax, 3 },
+		{ 0, 3, pfn(0, 1, 3), 3 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 3, pfn(1, 2, 4), 3 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 3, pfn(1, 3, 4), 3 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 4, pfn(0, 1, 3, 4), 4 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 5, pfn(0, 1, 3, 4, 5), 5 * PAGE_SIZE, sgmax, 2 },
+		{ 0, 5, pfn(0, 1, 3, 4, 6), 5 * PAGE_SIZE, sgmax, 3 },
+		{ 0, 5, pfn(0, 1, 2, 3, 4), 5 * PAGE_SIZE, sgmax, 1 },
+		{ 0, 5, pfn(0, 1, 2, 3, 4), 5 * PAGE_SIZE, 2 * PAGE_SIZE, 3 },
+		{ 0, 6, pfn(0, 1, 2, 3, 4, 5), 6 * PAGE_SIZE, 2 * PAGE_SIZE, 3 },
+		{ 0, 6, pfn(0, 2, 3, 4, 5, 6), 6 * PAGE_SIZE, 2 * PAGE_SIZE, 4 },
+		{ 0, 6, pfn(0, 1, 3, 4, 5, 6), 6 * PAGE_SIZE, 2 * PAGE_SIZE, 3 },
+		{ 0, 0, NULL, 0, 0, 0 },
+	};
+	unsigned int i;
+
+	for (i = 0, test = tests; test->expected_segments; test++, i++) {
+		struct page *pages[MAX_PAGES];
+		struct sg_table st;
+		int ret;
+
+		set_pages(pages, test->pfn, test->num_pages);
+
+		ret = __sg_alloc_table_from_pages(&st, pages, test->num_pages,
+						  0, test->size, test->max_seg,
+						  GFP_KERNEL);
+		assert(ret == test->alloc_ret);
+
+		if (test->alloc_ret)
+			continue;
+
+		assert(st.nents == test->expected_segments);
+		assert(st.orig_nents == test->expected_segments);
+
+		sg_free_table(&st);
+	}
+
+	assert(i == (sizeof(tests) / sizeof(tests[0])) - 1);
+
+	return 0;
+}