[PATCH 5.19 144/155] ALSA: memalloc: Revive x86-specific WC page allocations again

Greg Kroah-Hartman
2022-09-06T14:21:02Z

From: Takashi Iwai <tiwai@suse.de>

commit a8d302a0b77057568350fe0123e639d02dba0745 upstream.

We dropped the x86-specific hack for WC-page allocations with a hope
that the standard dma_alloc_wc() works nowadays. Alas, it doesn't,
and we need to take back some workaround again, but in a different
form, as the previous one was broken for some platforms.

This patch re-introduces the x86-specific WC-page allocations, but it
uses rather the manual page allocations instead of
dma_alloc_coherent(). The use of dma_alloc_coherent() was also a
potential problem in the recent addition of the fallback allocation
for noncontig pages, and this patch eliminates both at once.

Fixes: 9882d63bea14 ("ALSA: memalloc: Drop x86-specific hack for WC allocations")
Cc: <stable@vger.kernel.org>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216363
Link: https://lore.kernel.org/r/20220821155911.10715-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/core/memalloc.c | 87 ++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 71 insertions(+), 16 deletions(-)

--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -20,6 +20,13 @@

static const struct snd_malloc_ops *snd_dma_get_ops(struct snd_dma_buffer *dmab);

+#ifdef CONFIG_SND_DMA_SGBUF
+static void *do_alloc_fallback_pages(struct device *dev, size_t size,
+ dma_addr_t *addr, bool wc);
+static void do_free_fallback_pages(void *p, size_t size, bool wc);
+static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size);
+#endif
+
/* a cast to gfp flag from the dev pointer; for CONTINUOUS and VMALLOC types */
static inline gfp_t snd_mem_get_gfp_flags(const struct snd_dma_buffer *dmab,
gfp_t default_gfp)
@@ -269,16 +276,21 @@ EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);
/*
* Continuous pages allocator
*/
-static void *snd_dma_continuous_alloc(struct snd_dma_buffer *dmab, size_t size)
+static void *do_alloc_pages(size_t size, dma_addr_t *addr, gfp_t gfp)
{
- gfp_t gfp = snd_mem_get_gfp_flags(dmab, GFP_KERNEL);
void *p = alloc_pages_exact(size, gfp);

if (p)
- dmab->addr = page_to_phys(virt_to_page(p));
+ *addr = page_to_phys(virt_to_page(p));
return p;
}

+static void *snd_dma_continuous_alloc(struct snd_dma_buffer *dmab, size_t size)
+{
+ return do_alloc_pages(size, &dmab->addr,
+ snd_mem_get_gfp_flags(dmab, GFP_KERNEL));
+}
+
static void snd_dma_continuous_free(struct snd_dma_buffer *dmab)
{
free_pages_exact(dmab->area, dmab->bytes);
@@ -455,6 +467,25 @@ static const struct snd_malloc_ops snd_d
/*
* Write-combined pages
*/
+/* x86-specific allocations */
+#ifdef CONFIG_SND_DMA_SGBUF
+static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
+{
+ return do_alloc_fallback_pages(dmab->dev.dev, size, &dmab->addr, true);
+}
+
+static void snd_dma_wc_free(struct snd_dma_buffer *dmab)
+{
+ do_free_fallback_pages(dmab->area, dmab->bytes, true);
+}
+
+static int snd_dma_wc_mmap(struct snd_dma_buffer *dmab,
+ struct vm_area_struct *area)
+{
+ area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
+ return snd_dma_continuous_mmap(dmab, area);
+}
+#else
static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
{
return dma_alloc_wc(dmab->dev.dev, size, &dmab->addr, DEFAULT_GFP);
@@ -471,6 +502,7 @@ static int snd_dma_wc_mmap(struct snd_dm
return dma_mmap_wc(dmab->dev.dev, area,
dmab->area, dmab->addr, dmab->bytes);
}
+#endif /* CONFIG_SND_DMA_SGBUF */

static const struct snd_malloc_ops snd_dma_wc_ops = {
.alloc = snd_dma_wc_alloc,
@@ -478,10 +510,6 @@ static const struct snd_malloc_ops snd_d
.mmap = snd_dma_wc_mmap,
};

-#ifdef CONFIG_SND_DMA_SGBUF
-static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size);
-#endif
-
/*
* Non-contiguous pages allocator
*/
@@ -661,6 +689,37 @@ static const struct snd_malloc_ops snd_d
.get_chunk_size = snd_dma_noncontig_get_chunk_size,
};

+/* manual page allocations with wc setup */
+static void *do_alloc_fallback_pages(struct device *dev, size_t size,
+ dma_addr_t *addr, bool wc)
+{
+ gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
+ void *p;
+
+ again:
+ p = do_alloc_pages(size, addr, gfp);
+ if (!p || (*addr + size - 1) & ~dev->coherent_dma_mask) {
+ if (IS_ENABLED(CONFIG_ZONE_DMA32) && !(gfp & GFP_DMA32)) {
+ gfp |= GFP_DMA32;
+ goto again;
+ }
+ if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
+ gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
+ goto again;
+ }
+ }
+ if (p && wc)
+ set_memory_wc((unsigned long)(p), size >> PAGE_SHIFT);
+ return p;
+}
+
+static void do_free_fallback_pages(void *p, size_t size, bool wc)
+{
+ if (wc)
+ set_memory_wb((unsigned long)(p), size >> PAGE_SHIFT);
+ free_pages_exact(p, size);
+}
+
/* Fallback SG-buffer allocations for x86 */
struct snd_dma_sg_fallback {
size_t count;
@@ -671,14 +730,11 @@ struct snd_dma_sg_fallback {
static void __snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab,
struct snd_dma_sg_fallback *sgbuf)
{
+ bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
size_t i;

- if (sgbuf->count && dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
- set_pages_array_wb(sgbuf->pages, sgbuf->count);
for (i = 0; i < sgbuf->count && sgbuf->pages[i]; i++)
- dma_free_coherent(dmab->dev.dev, PAGE_SIZE,
- page_address(sgbuf->pages[i]),
- sgbuf->addrs[i]);
+ do_free_fallback_pages(page_address(sgbuf->pages[i]), PAGE_SIZE, wc);
kvfree(sgbuf->pages);
kvfree(sgbuf->addrs);
kfree(sgbuf);
@@ -690,6 +746,7 @@ static void *snd_dma_sg_fallback_alloc(s
struct page **pages;
size_t i, count;
void *p;
+ bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;

sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
if (!sgbuf)
@@ -704,15 +761,13 @@ static void *snd_dma_sg_fallback_alloc(s
goto error;

for (i = 0; i < count; sgbuf->count++, i++) {
- p = dma_alloc_coherent(dmab->dev.dev, PAGE_SIZE,
- &sgbuf->addrs[i], DEFAULT_GFP);
+ p = do_alloc_fallback_pages(dmab->dev.dev, PAGE_SIZE,
+ &sgbuf->addrs[i], wc);
if (!p)
goto error;
sgbuf->pages[i] = virt_to_page(p);
}

- if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
- set_pages_array_wc(pages, count);
p = vmap(pages, count, VM_MAP, PAGE_KERNEL);
if (!p)
goto error;