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Subject[RFC PATCH] powerpc/spufs: fix copy_to_user while atomic
Date
Currently, we may perform a copy_to_user (through
simple_read_from_buffer()) while holding a context's register_lock,
while accessing the context save area.

This change uses a temporary buffers for the context save area data,
which we then pass to simple_read_from_buffer.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
---

Christoph - this fixes the copy_to_user while atomic, hopefully with
only minimal distruption to your series.

---
arch/powerpc/platforms/cell/spufs/file.c | 110 +++++++++++++++--------
1 file changed, 74 insertions(+), 36 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index c0f950a3f4e1..c62d77ddaf7d 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -1978,8 +1978,9 @@ static ssize_t __spufs_mbox_info_read(struct spu_context *ctx,
static ssize_t spufs_mbox_info_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
- int ret;
struct spu_context *ctx = file->private_data;
+ u32 stat, data;
+ int ret;

if (!access_ok(buf, len))
return -EFAULT;
@@ -1988,11 +1989,16 @@ static ssize_t spufs_mbox_info_read(struct file *file, char __user *buf,
if (ret)
return ret;
spin_lock(&ctx->csa.register_lock);
- ret = __spufs_mbox_info_read(ctx, buf, len, pos);
+ stat = ctx->csa.prob.mb_stat_R;
+ data = ctx->csa.prob.pu_mb_R;
spin_unlock(&ctx->csa.register_lock);
spu_release_saved(ctx);

- return ret;
+ /* EOF if there's no entry in the mbox */
+ if (!(stat & 0x0000ff))
+ return 0;
+
+ return simple_read_from_buffer(buf, len, pos, &data, sizeof(data));
}

static const struct file_operations spufs_mbox_info_fops = {
@@ -2019,6 +2025,7 @@ static ssize_t spufs_ibox_info_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
struct spu_context *ctx = file->private_data;
+ u32 stat, data;
int ret;

if (!access_ok(buf, len))
@@ -2028,11 +2035,16 @@ static ssize_t spufs_ibox_info_read(struct file *file, char __user *buf,
if (ret)
return ret;
spin_lock(&ctx->csa.register_lock);
- ret = __spufs_ibox_info_read(ctx, buf, len, pos);
+ stat = ctx->csa.prob.mb_stat_R;
+ data = ctx->csa.priv2.puint_mb_R;
spin_unlock(&ctx->csa.register_lock);
spu_release_saved(ctx);

- return ret;
+ /* EOF if there's no entry in the ibox */
+ if (!(stat & 0xff0000))
+ return 0;
+
+ return simple_read_from_buffer(buf, len, pos, &data, sizeof(data));
}

static const struct file_operations spufs_ibox_info_fops = {
@@ -2041,6 +2053,11 @@ static const struct file_operations spufs_ibox_info_fops = {
.llseek = generic_file_llseek,
};

+static size_t spufs_wbox_info_cnt(struct spu_context *ctx)
+{
+ return (4 - ((ctx->csa.prob.mb_stat_R & 0x00ff00) >> 8)) * sizeof(u32);
+}
+
static ssize_t __spufs_wbox_info_read(struct spu_context *ctx,
char __user *buf, size_t len, loff_t *pos)
{
@@ -2049,7 +2066,7 @@ static ssize_t __spufs_wbox_info_read(struct spu_context *ctx,
u32 wbox_stat;

wbox_stat = ctx->csa.prob.mb_stat_R;
- cnt = 4 - ((wbox_stat & 0x00ff00) >> 8);
+ cnt = spufs_wbox_info_cnt(ctx);
for (i = 0; i < cnt; i++) {
data[i] = ctx->csa.spu_mailbox_data[i];
}
@@ -2062,7 +2079,8 @@ static ssize_t spufs_wbox_info_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
struct spu_context *ctx = file->private_data;
- int ret;
+ u32 data[ARRAY_SIZE(ctx->csa.spu_mailbox_data)];
+ int ret, count;

if (!access_ok(buf, len))
return -EFAULT;
@@ -2071,11 +2089,13 @@ static ssize_t spufs_wbox_info_read(struct file *file, char __user *buf,
if (ret)
return ret;
spin_lock(&ctx->csa.register_lock);
- ret = __spufs_wbox_info_read(ctx, buf, len, pos);
+ count = spufs_wbox_info_cnt(ctx);
+ memcpy(&data, &ctx->csa.spu_mailbox_data, sizeof(data));
spin_unlock(&ctx->csa.register_lock);
spu_release_saved(ctx);

- return ret;
+ return simple_read_from_buffer(buf, len, pos, &data,
+ count * sizeof(u32));
}

static const struct file_operations spufs_wbox_info_fops = {
@@ -2084,20 +2104,19 @@ static const struct file_operations spufs_wbox_info_fops = {
.llseek = generic_file_llseek,
};

-static ssize_t __spufs_dma_info_read(struct spu_context *ctx,
- char __user *buf, size_t len, loff_t *pos)
+static void ___spufs_dma_info_read(struct spu_context *ctx,
+ struct spu_dma_info *info)
{
- struct spu_dma_info info;
struct mfc_cq_sr *qp, *spuqp;
int i;

- info.dma_info_type = ctx->csa.priv2.spu_tag_status_query_RW;
- info.dma_info_mask = ctx->csa.lscsa->tag_mask.slot[0];
- info.dma_info_status = ctx->csa.spu_chnldata_RW[24];
- info.dma_info_stall_and_notify = ctx->csa.spu_chnldata_RW[25];
- info.dma_info_atomic_command_status = ctx->csa.spu_chnldata_RW[27];
+ info->dma_info_type = ctx->csa.priv2.spu_tag_status_query_RW;
+ info->dma_info_mask = ctx->csa.lscsa->tag_mask.slot[0];
+ info->dma_info_status = ctx->csa.spu_chnldata_RW[24];
+ info->dma_info_stall_and_notify = ctx->csa.spu_chnldata_RW[25];
+ info->dma_info_atomic_command_status = ctx->csa.spu_chnldata_RW[27];
for (i = 0; i < 16; i++) {
- qp = &info.dma_info_command_data[i];
+ qp = &info->dma_info_command_data[i];
spuqp = &ctx->csa.priv2.spuq[i];

qp->mfc_cq_data0_RW = spuqp->mfc_cq_data0_RW;
@@ -2105,6 +2124,14 @@ static ssize_t __spufs_dma_info_read(struct spu_context *ctx,
qp->mfc_cq_data2_RW = spuqp->mfc_cq_data2_RW;
qp->mfc_cq_data3_RW = spuqp->mfc_cq_data3_RW;
}
+}
+
+static ssize_t __spufs_dma_info_read(struct spu_context *ctx,
+ char __user *buf, size_t len, loff_t *pos)
+{
+ struct spu_dma_info info;
+
+ ___spufs_dma_info_read(ctx, &info);

return simple_read_from_buffer(buf, len, pos, &info,
sizeof info);
@@ -2114,6 +2141,7 @@ static ssize_t spufs_dma_info_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
struct spu_context *ctx = file->private_data;
+ struct spu_dma_info info;
int ret;

if (!access_ok(buf, len))
@@ -2123,11 +2151,12 @@ static ssize_t spufs_dma_info_read(struct file *file, char __user *buf,
if (ret)
return ret;
spin_lock(&ctx->csa.register_lock);
- ret = __spufs_dma_info_read(ctx, buf, len, pos);
+ ___spufs_dma_info_read(ctx, &info);
spin_unlock(&ctx->csa.register_lock);
spu_release_saved(ctx);

- return ret;
+ return simple_read_from_buffer(buf, len, pos, &info,
+ sizeof(info));
}

static const struct file_operations spufs_dma_info_fops = {
@@ -2136,13 +2165,31 @@ static const struct file_operations spufs_dma_info_fops = {
.llseek = no_llseek,
};

+static void ___spufs_proxydma_info_read(struct spu_context *ctx,
+ struct spu_proxydma_info *info)
+{
+ int i;
+
+ info->proxydma_info_type = ctx->csa.prob.dma_querytype_RW;
+ info->proxydma_info_mask = ctx->csa.prob.dma_querymask_RW;
+ info->proxydma_info_status = ctx->csa.prob.dma_tagstatus_R;
+
+ for (i = 0; i < 8; i++) {
+ struct mfc_cq_sr *qp = &info->proxydma_info_command_data[i];
+ struct mfc_cq_sr *puqp = &ctx->csa.priv2.puq[i];
+
+ qp->mfc_cq_data0_RW = puqp->mfc_cq_data0_RW;
+ qp->mfc_cq_data1_RW = puqp->mfc_cq_data1_RW;
+ qp->mfc_cq_data2_RW = puqp->mfc_cq_data2_RW;
+ qp->mfc_cq_data3_RW = puqp->mfc_cq_data3_RW;
+ }
+}
+
static ssize_t __spufs_proxydma_info_read(struct spu_context *ctx,
char __user *buf, size_t len, loff_t *pos)
{
struct spu_proxydma_info info;
- struct mfc_cq_sr *qp, *puqp;
int ret = sizeof info;
- int i;

if (len < ret)
return -EINVAL;
@@ -2150,18 +2197,7 @@ static ssize_t __spufs_proxydma_info_read(struct spu_context *ctx,
if (!access_ok(buf, len))
return -EFAULT;

- info.proxydma_info_type = ctx->csa.prob.dma_querytype_RW;
- info.proxydma_info_mask = ctx->csa.prob.dma_querymask_RW;
- info.proxydma_info_status = ctx->csa.prob.dma_tagstatus_R;
- for (i = 0; i < 8; i++) {
- qp = &info.proxydma_info_command_data[i];
- puqp = &ctx->csa.priv2.puq[i];
-
- qp->mfc_cq_data0_RW = puqp->mfc_cq_data0_RW;
- qp->mfc_cq_data1_RW = puqp->mfc_cq_data1_RW;
- qp->mfc_cq_data2_RW = puqp->mfc_cq_data2_RW;
- qp->mfc_cq_data3_RW = puqp->mfc_cq_data3_RW;
- }
+ ___spufs_proxydma_info_read(ctx, &info);

return simple_read_from_buffer(buf, len, pos, &info,
sizeof info);
@@ -2171,17 +2207,19 @@ static ssize_t spufs_proxydma_info_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
struct spu_context *ctx = file->private_data;
+ struct spu_proxydma_info info;
int ret;

ret = spu_acquire_saved(ctx);
if (ret)
return ret;
spin_lock(&ctx->csa.register_lock);
- ret = __spufs_proxydma_info_read(ctx, buf, len, pos);
+ ___spufs_proxydma_info_read(ctx, &info);
spin_unlock(&ctx->csa.register_lock);
spu_release_saved(ctx);

- return ret;
+ return simple_read_from_buffer(buf, len, pos, &info,
+ sizeof(info));
}

static const struct file_operations spufs_proxydma_info_fops = {
--
2.17.1
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