[PATCH 3/7] powerpc/spufs: simplify spufs core dumping

From: Christoph Hellwig
Date: Tue May 05 2020 - 06:13:29 EST

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Replace the coredump ->read method with a ->dump method that must call
dump_emit itself. That way we avoid a buffer allocation an messing with
set_fs() to call into code that is intended to deal with user buffers.
For the ->get case we can now use a small on-stack buffer and avoid
memory allocations as well.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Jeremy Kerr <jk@xxxxxxxxxx>
---
arch/powerpc/platforms/cell/spufs/coredump.c | 87 +++-----
arch/powerpc/platforms/cell/spufs/file.c | 203 ++++++++-----------
arch/powerpc/platforms/cell/spufs/spufs.h | 3 +-
3 files changed, 117 insertions(+), 176 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 8b3296b62f651..3b75e8f60609c 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -21,22 +21,6 @@

#include "spufs.h"

-static ssize_t do_coredump_read(int num, struct spu_context *ctx, void *buffer,
- size_t size, loff_t *off)
-{
- u64 data;
- int ret;
-
- if (spufs_coredump_read[num].read)
- return spufs_coredump_read[num].read(ctx, buffer, size, off);
-
- data = spufs_coredump_read[num].get(ctx);
- ret = snprintf(buffer, size, "0x%.16llx", data);
- if (ret >= size)
- return size;
- return ++ret; /* count trailing NULL */
-}
-
static int spufs_ctx_note_size(struct spu_context *ctx, int dfd)
{
int i, sz, total = 0;
@@ -118,58 +102,43 @@ int spufs_coredump_extra_notes_size(void)
static int spufs_arch_write_note(struct spu_context *ctx, int i,
struct coredump_params *cprm, int dfd)
{
- loff_t pos = 0;
- int sz, rc, total = 0;
- const int bufsz = PAGE_SIZE;
- char *name;
- char fullname[80], *buf;
+ size_t sz = spufs_coredump_read[i].size;
+ char fullname[80];
struct elf_note en;
- size_t skip;
-
- buf = (void *)get_zeroed_page(GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
+ size_t ret;

- name = spufs_coredump_read[i].name;
- sz = spufs_coredump_read[i].size;
-
- sprintf(fullname, "SPU/%d/%s", dfd, name);
+ sprintf(fullname, "SPU/%d/%s", dfd, spufs_coredump_read[i].name);
en.n_namesz = strlen(fullname) + 1;
en.n_descsz = sz;
en.n_type = NT_SPU;

if (!dump_emit(cprm, &en, sizeof(en)))
- goto Eio;
-
+ return -EIO;
if (!dump_emit(cprm, fullname, en.n_namesz))
- goto Eio;
-
+ return -EIO;
if (!dump_align(cprm, 4))
- goto Eio;
-
- do {
- rc = do_coredump_read(i, ctx, buf, bufsz, &pos);
- if (rc > 0) {
- if (!dump_emit(cprm, buf, rc))
- goto Eio;
- total += rc;
- }
- } while (rc == bufsz && total < sz);
-
- if (rc < 0)
- goto out;
-
- skip = roundup(cprm->pos - total + sz, 4) - cprm->pos;
- if (!dump_skip(cprm, skip))
- goto Eio;
-
- rc = 0;
-out:
- free_page((unsigned long)buf);
- return rc;
-Eio:
- free_page((unsigned long)buf);
- return -EIO;
+ return -EIO;
+
+ if (spufs_coredump_read[i].dump) {
+ ret = spufs_coredump_read[i].dump(ctx, cprm);
+ if (ret < 0)
+ return ret;
+ } else {
+ char buf[32];
+
+ ret = snprintf(buf, sizeof(buf), "0x%.16llx",
+ spufs_coredump_read[i].get(ctx));
+ if (ret >= sizeof(buf))
+ return sizeof(buf);
+
+ /* count trailing the NULL: */
+ if (!dump_emit(cprm, buf, ret + 1))
+ return -EIO;
+ }
+
+ if (!dump_skip(cprm, roundup(cprm->pos - ret + sz, 4) - cprm->pos))
+ return -EIO;
+ return 0;
}

int spufs_coredump_extra_notes_write(struct coredump_params *cprm)
diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index bd30b5e0c4c37..e44427c245850 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -9,6 +9,7 @@

#undef DEBUG

+#include <linux/coredump.h>
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/export.h>
@@ -129,6 +130,14 @@ static ssize_t spufs_attr_write(struct file *file, const char __user *buf,
return ret;
}

+static ssize_t spufs_dump_emit(struct coredump_params *cprm, void *buf,
+ size_t size)
+{
+ if (!dump_emit(cprm, buf, size))
+ return -EIO;
+ return size;
+}
+
#define DEFINE_SPUFS_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt) \
static int __fops ## _open(struct inode *inode, struct file *file) \
{ \
@@ -172,12 +181,9 @@ spufs_mem_release(struct inode *inode, struct file *file)
}

static ssize_t
-__spufs_mem_read(struct spu_context *ctx, char __user *buffer,
- size_t size, loff_t *pos)
+spufs_mem_dump(struct spu_context *ctx, struct coredump_params *cprm)
{
- char *local_store = ctx->ops->get_ls(ctx);
- return simple_read_from_buffer(buffer, size, pos, local_store,
- LS_SIZE);
+ return spufs_dump_emit(cprm, ctx->ops->get_ls(ctx), LS_SIZE);
}

static ssize_t
@@ -190,7 +196,8 @@ spufs_mem_read(struct file *file, char __user *buffer,
ret = spu_acquire(ctx);
if (ret)
return ret;
- ret = __spufs_mem_read(ctx, buffer, size, pos);
+ ret = simple_read_from_buffer(buffer, size, pos, ctx->ops->get_ls(ctx),
+ LS_SIZE);
spu_release(ctx);

return ret;
@@ -459,12 +466,10 @@ spufs_regs_open(struct inode *inode, struct file *file)
}

static ssize_t
-__spufs_regs_read(struct spu_context *ctx, char __user *buffer,
- size_t size, loff_t *pos)
+spufs_regs_dump(struct spu_context *ctx, struct coredump_params *cprm)
{
- struct spu_lscsa *lscsa = ctx->csa.lscsa;
- return simple_read_from_buffer(buffer, size, pos,
- lscsa->gprs, sizeof lscsa->gprs);
+ return spufs_dump_emit(cprm, ctx->csa.lscsa->gprs,
+ sizeof(ctx->csa.lscsa->gprs));
}

static ssize_t
@@ -482,7 +487,8 @@ spufs_regs_read(struct file *file, char __user *buffer,
ret = spu_acquire_saved(ctx);
if (ret)
return ret;
- ret = __spufs_regs_read(ctx, buffer, size, pos);
+ ret = simple_read_from_buffer(buffer, size, pos, ctx->csa.lscsa->gprs,
+ sizeof(ctx->csa.lscsa->gprs));
spu_release_saved(ctx);
return ret;
}
@@ -517,12 +523,10 @@ static const struct file_operations spufs_regs_fops = {
};

static ssize_t
-__spufs_fpcr_read(struct spu_context *ctx, char __user * buffer,
- size_t size, loff_t * pos)
+spufs_fpcr_dump(struct spu_context *ctx, struct coredump_params *cprm)
{
- struct spu_lscsa *lscsa = ctx->csa.lscsa;
- return simple_read_from_buffer(buffer, size, pos,
- &lscsa->fpcr, sizeof(lscsa->fpcr));
+ return spufs_dump_emit(cprm, &ctx->csa.lscsa->fpcr,
+ sizeof(ctx->csa.lscsa->fpcr));
}

static ssize_t
@@ -535,7 +539,8 @@ spufs_fpcr_read(struct file *file, char __user * buffer,
ret = spu_acquire_saved(ctx);
if (ret)
return ret;
- ret = __spufs_fpcr_read(ctx, buffer, size, pos);
+ ret = simple_read_from_buffer(buffer, size, pos, &ctx->csa.lscsa->fpcr,
+ sizeof(ctx->csa.lscsa->fpcr));
spu_release_saved(ctx);
return ret;
}
@@ -953,28 +958,26 @@ spufs_signal1_release(struct inode *inode, struct file *file)
return 0;
}

-static ssize_t __spufs_signal1_read(struct spu_context *ctx, char __user *buf,
- size_t len, loff_t *pos)
+static ssize_t spufs_signal1_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
- int ret = 0;
- u32 data;
+ if (!ctx->csa.spu_chnlcnt_RW[3])
+ return 0;
+ return spufs_dump_emit(cprm, &ctx->csa.spu_chnldata_RW[3],
+ sizeof(ctx->csa.spu_chnldata_RW[3]));
+}

- if (len < 4)
+static ssize_t __spufs_signal1_read(struct spu_context *ctx, char __user *buf,
+ size_t len)
+{
+ if (len < sizeof(ctx->csa.spu_chnldata_RW[3]))
return -EINVAL;
-
- if (ctx->csa.spu_chnlcnt_RW[3]) {
- data = ctx->csa.spu_chnldata_RW[3];
- ret = 4;
- }
-
- if (!ret)
- goto out;
-
- if (copy_to_user(buf, &data, 4))
+ if (!ctx->csa.spu_chnlcnt_RW[3])
+ return 0;
+ if (copy_to_user(buf, &ctx->csa.spu_chnldata_RW[3],
+ sizeof(ctx->csa.spu_chnldata_RW[3])))
return -EFAULT;
-
-out:
- return ret;
+ return sizeof(ctx->csa.spu_chnldata_RW[3]);
}

static ssize_t spufs_signal1_read(struct file *file, char __user *buf,
@@ -986,7 +989,7 @@ static ssize_t spufs_signal1_read(struct file *file, char __user *buf,
ret = spu_acquire_saved(ctx);
if (ret)
return ret;
- ret = __spufs_signal1_read(ctx, buf, len, pos);
+ ret = __spufs_signal1_read(ctx, buf, len);
spu_release_saved(ctx);

return ret;
@@ -1090,28 +1093,26 @@ spufs_signal2_release(struct inode *inode, struct file *file)
return 0;
}

-static ssize_t __spufs_signal2_read(struct spu_context *ctx, char __user *buf,
- size_t len, loff_t *pos)
+static ssize_t spufs_signal2_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
- int ret = 0;
- u32 data;
+ if (!ctx->csa.spu_chnlcnt_RW[4])
+ return 0;
+ return spufs_dump_emit(cprm, &ctx->csa.spu_chnldata_RW[4],
+ sizeof(ctx->csa.spu_chnldata_RW[4]));
+}

- if (len < 4)
+static ssize_t __spufs_signal2_read(struct spu_context *ctx, char __user *buf,
+ size_t len)
+{
+ if (len < sizeof(ctx->csa.spu_chnldata_RW[4]))
return -EINVAL;
-
- if (ctx->csa.spu_chnlcnt_RW[4]) {
- data = ctx->csa.spu_chnldata_RW[4];
- ret = 4;
- }
-
- if (!ret)
- goto out;
-
- if (copy_to_user(buf, &data, 4))
+ if (!ctx->csa.spu_chnlcnt_RW[4])
+ return 0;
+ if (copy_to_user(buf, &ctx->csa.spu_chnldata_RW[4],
+ sizeof(ctx->csa.spu_chnldata_RW[4])))
return -EFAULT;
-
-out:
- return ret;
+ return sizeof(ctx->csa.spu_chnldata_RW[4]);
}

static ssize_t spufs_signal2_read(struct file *file, char __user *buf,
@@ -1123,7 +1124,7 @@ static ssize_t spufs_signal2_read(struct file *file, char __user *buf,
ret = spu_acquire_saved(ctx);
if (ret)
return ret;
- ret = __spufs_signal2_read(ctx, buf, len, pos);
+ ret = __spufs_signal2_read(ctx, buf, len);
spu_release_saved(ctx);

return ret;
@@ -1947,18 +1948,13 @@ static const struct file_operations spufs_caps_fops = {
.release = single_release,
};

-static ssize_t __spufs_mbox_info_read(struct spu_context *ctx,
- char __user *buf, size_t len, loff_t *pos)
+static ssize_t spufs_mbox_info_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
- u32 data;
-
- /* EOF if there's no entry in the mbox */
if (!(ctx->csa.prob.mb_stat_R & 0x0000ff))
return 0;
-
- data = ctx->csa.prob.pu_mb_R;
-
- return simple_read_from_buffer(buf, len, pos, &data, sizeof data);
+ return spufs_dump_emit(cprm, &ctx->csa.prob.pu_mb_R,
+ sizeof(ctx->csa.prob.pu_mb_R));
}

static ssize_t spufs_mbox_info_read(struct file *file, char __user *buf,
@@ -1990,18 +1986,13 @@ static const struct file_operations spufs_mbox_info_fops = {
.llseek = generic_file_llseek,
};

-static ssize_t __spufs_ibox_info_read(struct spu_context *ctx,
- char __user *buf, size_t len, loff_t *pos)
+static ssize_t spufs_ibox_info_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
- u32 data;
-
- /* EOF if there's no entry in the ibox */
if (!(ctx->csa.prob.mb_stat_R & 0xff0000))
return 0;
-
- data = ctx->csa.priv2.puint_mb_R;
-
- return simple_read_from_buffer(buf, len, pos, &data, sizeof data);
+ return spufs_dump_emit(cprm, &ctx->csa.priv2.puint_mb_R,
+ sizeof(ctx->csa.priv2.puint_mb_R));
}

static ssize_t spufs_ibox_info_read(struct file *file, char __user *buf,
@@ -2038,21 +2029,11 @@ 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)
+static ssize_t spufs_wbox_info_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
- int i, cnt;
- u32 data[4];
- u32 wbox_stat;
-
- wbox_stat = ctx->csa.prob.mb_stat_R;
- cnt = spufs_wbox_info_cnt(ctx);
- for (i = 0; i < cnt; i++) {
- data[i] = ctx->csa.spu_mailbox_data[i];
- }
-
- return simple_read_from_buffer(buf, len, pos, &data,
- cnt * sizeof(u32));
+ return spufs_dump_emit(cprm, &ctx->csa.spu_mailbox_data,
+ spufs_wbox_info_cnt(ctx));
}

static ssize_t spufs_wbox_info_read(struct file *file, char __user *buf,
@@ -2102,15 +2083,13 @@ static void spufs_get_dma_info(struct spu_context *ctx,
}
}

-static ssize_t __spufs_dma_info_read(struct spu_context *ctx,
- char __user *buf, size_t len, loff_t *pos)
+static ssize_t spufs_dma_info_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
struct spu_dma_info info;

spufs_get_dma_info(ctx, &info);
-
- return simple_read_from_buffer(buf, len, pos, &info,
- sizeof info);
+ return spufs_dump_emit(cprm, &info, sizeof(info));
}

static ssize_t spufs_dma_info_read(struct file *file, char __user *buf,
@@ -2158,22 +2137,13 @@ static void spufs_get_proxydma_info(struct spu_context *ctx,
}
}

-static ssize_t __spufs_proxydma_info_read(struct spu_context *ctx,
- char __user *buf, size_t len, loff_t *pos)
+static ssize_t spufs_proxydma_info_dump(struct spu_context *ctx,
+ struct coredump_params *cprm)
{
struct spu_proxydma_info info;
- int ret = sizeof info;
-
- if (len < ret)
- return -EINVAL;
-
- if (!access_ok(buf, len))
- return -EFAULT;

spufs_get_proxydma_info(ctx, &info);
-
- return simple_read_from_buffer(buf, len, pos, &info,
- sizeof info);
+ return spufs_dump_emit(cprm, &info, sizeof(info));
}

static ssize_t spufs_proxydma_info_read(struct file *file, char __user *buf,
@@ -2183,6 +2153,9 @@ static ssize_t spufs_proxydma_info_read(struct file *file, char __user *buf,
struct spu_proxydma_info info;
int ret;

+ if (len < sizeof(info))
+ return -EINVAL;
+
ret = spu_acquire_saved(ctx);
if (ret)
return ret;
@@ -2636,23 +2609,23 @@ const struct spufs_tree_descr spufs_dir_debug_contents[] = {
};

const struct spufs_coredump_reader spufs_coredump_read[] = {
- { "regs", __spufs_regs_read, NULL, sizeof(struct spu_reg128[128])},
- { "fpcr", __spufs_fpcr_read, NULL, sizeof(struct spu_reg128) },
+ { "regs", spufs_regs_dump, NULL, sizeof(struct spu_reg128[128])},
+ { "fpcr", spufs_fpcr_dump, NULL, sizeof(struct spu_reg128) },
{ "lslr", NULL, spufs_lslr_get, 19 },
{ "decr", NULL, spufs_decr_get, 19 },
{ "decr_status", NULL, spufs_decr_status_get, 19 },
- { "mem", __spufs_mem_read, NULL, LS_SIZE, },
- { "signal1", __spufs_signal1_read, NULL, sizeof(u32) },
+ { "mem", spufs_mem_dump, NULL, LS_SIZE, },
+ { "signal1", spufs_signal1_dump, NULL, sizeof(u32) },
{ "signal1_type", NULL, spufs_signal1_type_get, 19 },
- { "signal2", __spufs_signal2_read, NULL, sizeof(u32) },
+ { "signal2", spufs_signal2_dump, NULL, sizeof(u32) },
{ "signal2_type", NULL, spufs_signal2_type_get, 19 },
{ "event_mask", NULL, spufs_event_mask_get, 19 },
{ "event_status", NULL, spufs_event_status_get, 19 },
- { "mbox_info", __spufs_mbox_info_read, NULL, sizeof(u32) },
- { "ibox_info", __spufs_ibox_info_read, NULL, sizeof(u32) },
- { "wbox_info", __spufs_wbox_info_read, NULL, 4 * sizeof(u32)},
- { "dma_info", __spufs_dma_info_read, NULL, sizeof(struct spu_dma_info)},
- { "proxydma_info", __spufs_proxydma_info_read,
+ { "mbox_info", spufs_mbox_info_dump, NULL, sizeof(u32) },
+ { "ibox_info", spufs_ibox_info_dump, NULL, sizeof(u32) },
+ { "wbox_info", spufs_wbox_info_dump, NULL, 4 * sizeof(u32)},
+ { "dma_info", spufs_dma_info_dump, NULL, sizeof(struct spu_dma_info)},
+ { "proxydma_info", spufs_proxydma_info_dump,
NULL, sizeof(struct spu_proxydma_info)},
{ "object-id", NULL, spufs_object_id_get, 19 },
{ "npc", NULL, spufs_npc_get, 19 },
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 413c89afe1126..1ba4d884febfa 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -337,8 +337,7 @@ void spufs_dma_callback(struct spu *spu, int type);
extern struct spu_coredump_calls spufs_coredump_calls;
struct spufs_coredump_reader {
char *name;
- ssize_t (*read)(struct spu_context *ctx,
- char __user *buffer, size_t size, loff_t *pos);
+ ssize_t (*dump)(struct spu_context *ctx, struct coredump_params *cprm);
u64 (*get)(struct spu_context *ctx);
size_t size;
};
--
2.26.2

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