| Message ID | a84da6cc458b44d949058b5f475ed3225008cfd9.1679431886.git.lstoakes@gmail.com (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | convert read_kcore(), vread() to use iterators | expand |
Hi Lorenzo, On 03/21/23 at 08:54pm, Lorenzo Stoakes wrote: > Now we have eliminated spinlocks from the vread() case, convert > read_kcore() to read_kcore_iter(). Sorry for late comment. Here I could miss something important, I don't get where we have eliminated spinlocks from the vread() case. Do I misunderstand this sentence? > > For the time being we still use a bounce buffer for vread(), however in the > next patch we will convert this to interact directly with the iterator and > eliminate the bounce buffer altogether. > > Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> > --- > fs/proc/kcore.c | 58 ++++++++++++++++++++++++------------------------- > 1 file changed, 29 insertions(+), 29 deletions(-) > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index 556f310d6aa4..25e0eeb8d498 100644 > --- a/fs/proc/kcore.c > +++ b/fs/proc/kcore.c > @@ -24,7 +24,7 @@ > #include <linux/memblock.h> > #include <linux/init.h> > #include <linux/slab.h> > -#include <linux/uaccess.h> > +#include <linux/uio.h> > #include <asm/io.h> > #include <linux/list.h> > #include <linux/ioport.h> > @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, > } > > static ssize_t > -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) > { > + struct file *file = iocb->ki_filp; > char *buf = file->private_data; > + loff_t *ppos = &iocb->ki_pos; > + > size_t phdrs_offset, notes_offset, data_offset; > size_t page_offline_frozen = 1; > size_t phdrs_len, notes_len; > @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > size_t tsz; > int nphdr; > unsigned long start; > + size_t buflen = iov_iter_count(iter); > size_t orig_buflen = buflen; > int ret = 0; > > @@ -333,7 +337,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > notes_offset = phdrs_offset + phdrs_len; > > /* ELF file header. */ > - if (buflen && *fpos < sizeof(struct elfhdr)) { > + if (buflen && *ppos < sizeof(struct elfhdr)) { > struct elfhdr ehdr = { > .e_ident = { > [EI_MAG0] = ELFMAG0, > @@ -355,19 +359,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > .e_phnum = nphdr, > }; > > - tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); > - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { > + tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *ppos); > + if (copy_to_iter((char *)&ehdr + *ppos, tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > > - buffer += tsz; > buflen -= tsz; > - *fpos += tsz; > + *ppos += tsz; > } > > /* ELF program headers. */ > - if (buflen && *fpos < phdrs_offset + phdrs_len) { > + if (buflen && *ppos < phdrs_offset + phdrs_len) { > struct elf_phdr *phdrs, *phdr; > > phdrs = kzalloc(phdrs_len, GFP_KERNEL); > @@ -397,22 +400,21 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > phdr++; > } > > - tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); > - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, > - tsz)) { > + tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *ppos); > + if (copy_to_iter((char *)phdrs + *ppos - phdrs_offset, tsz, > + iter) != tsz) { > kfree(phdrs); > ret = -EFAULT; > goto out; > } > kfree(phdrs); > > - buffer += tsz; > buflen -= tsz; > - *fpos += tsz; > + *ppos += tsz; > } > > /* ELF note segment. */ > - if (buflen && *fpos < notes_offset + notes_len) { > + if (buflen && *ppos < notes_offset + notes_len) { > struct elf_prstatus prstatus = {}; > struct elf_prpsinfo prpsinfo = { > .pr_sname = 'R', > @@ -447,24 +449,23 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > vmcoreinfo_data, > min(vmcoreinfo_size, notes_len - i)); > > - tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); > - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { > + tsz = min_t(size_t, buflen, notes_offset + notes_len - *ppos); > + if (copy_to_iter(notes + *ppos - notes_offset, tsz, iter) != tsz) { > kfree(notes); > ret = -EFAULT; > goto out; > } > kfree(notes); > > - buffer += tsz; > buflen -= tsz; > - *fpos += tsz; > + *ppos += tsz; > } > > /* > * Check to see if our file offset matches with any of > * the addresses in the elf_phdr on our list. > */ > - start = kc_offset_to_vaddr(*fpos - data_offset); > + start = kc_offset_to_vaddr(*ppos - data_offset); > if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) > tsz = buflen; > > @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > } > > if (!m) { > - if (clear_user(buffer, tsz)) { > + if (iov_iter_zero(tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > case KCORE_VMALLOC: > vread(buf, (char *)start, tsz); > /* we have to zero-fill user buffer even if no read */ > - if (copy_to_user(buffer, buf, tsz)) { > + if (copy_to_iter(buf, tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > break; > case KCORE_USER: > /* User page is handled prior to normal kernel page: */ > - if (copy_to_user(buffer, (char *)start, tsz)) { > + if (copy_to_iter((char *)start, tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > */ > if (!page || PageOffline(page) || > is_page_hwpoison(page) || !pfn_is_ram(pfn)) { > - if (clear_user(buffer, tsz)) { > + if (iov_iter_zero(tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > @@ -541,25 +542,24 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > case KCORE_VMEMMAP: > case KCORE_TEXT: > /* > - * We use _copy_to_user() to bypass usermode hardening > + * We use _copy_to_iter() to bypass usermode hardening > * which would otherwise prevent this operation. > */ > - if (_copy_to_user(buffer, (char *)start, tsz)) { > + if (_copy_to_iter((char *)start, tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > break; > default: > pr_warn_once("Unhandled KCORE type: %d\n", m->type); > - if (clear_user(buffer, tsz)) { > + if (iov_iter_zero(tsz, iter) != tsz) { > ret = -EFAULT; > goto out; > } > } > skip: > buflen -= tsz; > - *fpos += tsz; > - buffer += tsz; > + *ppos += tsz; > start += tsz; > tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); > } > @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct file *file) > } > > static const struct proc_ops kcore_proc_ops = { > - .proc_read = read_kcore, > + .proc_read_iter = read_kcore_iter, > .proc_open = open_kcore, > .proc_release = release_kcore, > .proc_lseek = default_llseek, > -- > 2.39.2 >
On Wed, Mar 22, 2023 at 09:15:48AM +0800, Baoquan He wrote: > Hi Lorenzo, > > On 03/21/23 at 08:54pm, Lorenzo Stoakes wrote: > > Now we have eliminated spinlocks from the vread() case, convert > > read_kcore() to read_kcore_iter(). > > Sorry for late comment. > > Here I could miss something important, I don't get where we have > eliminated spinlocks from the vread() case. Do I misunderstand this > sentence? > Apologies, I didn't update the commit message after the latest revision! We can just drop this sentence altogether. Andrew - could you change the commit message to simply read:- For the time being we still use a bounce buffer for vread(), however in the next patch we will convert this to interact directly with the iterator and eliminate the bounce buffer altogether. Thanks! > > > > For the time being we still use a bounce buffer for vread(), however in the > > next patch we will convert this to interact directly with the iterator and > > eliminate the bounce buffer altogether. > > > > Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> > > --- > > fs/proc/kcore.c | 58 ++++++++++++++++++++++++------------------------- > > 1 file changed, 29 insertions(+), 29 deletions(-) > > > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > > index 556f310d6aa4..25e0eeb8d498 100644 > > --- a/fs/proc/kcore.c > > +++ b/fs/proc/kcore.c > > @@ -24,7 +24,7 @@ > > #include <linux/memblock.h> > > #include <linux/init.h> > > #include <linux/slab.h> > > -#include <linux/uaccess.h> > > +#include <linux/uio.h> > > #include <asm/io.h> > > #include <linux/list.h> > > #include <linux/ioport.h> > > @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, > > } > > > > static ssize_t > > -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) > > { > > + struct file *file = iocb->ki_filp; > > char *buf = file->private_data; > > + loff_t *ppos = &iocb->ki_pos; > > + > > size_t phdrs_offset, notes_offset, data_offset; > > size_t page_offline_frozen = 1; > > size_t phdrs_len, notes_len; > > @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > size_t tsz; > > int nphdr; > > unsigned long start; > > + size_t buflen = iov_iter_count(iter); > > size_t orig_buflen = buflen; > > int ret = 0; > > > > @@ -333,7 +337,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > notes_offset = phdrs_offset + phdrs_len; > > > > /* ELF file header. */ > > - if (buflen && *fpos < sizeof(struct elfhdr)) { > > + if (buflen && *ppos < sizeof(struct elfhdr)) { > > struct elfhdr ehdr = { > > .e_ident = { > > [EI_MAG0] = ELFMAG0, > > @@ -355,19 +359,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > .e_phnum = nphdr, > > }; > > > > - tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); > > - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { > > + tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *ppos); > > + if (copy_to_iter((char *)&ehdr + *ppos, tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > > > - buffer += tsz; > > buflen -= tsz; > > - *fpos += tsz; > > + *ppos += tsz; > > } > > > > /* ELF program headers. */ > > - if (buflen && *fpos < phdrs_offset + phdrs_len) { > > + if (buflen && *ppos < phdrs_offset + phdrs_len) { > > struct elf_phdr *phdrs, *phdr; > > > > phdrs = kzalloc(phdrs_len, GFP_KERNEL); > > @@ -397,22 +400,21 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > phdr++; > > } > > > > - tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); > > - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, > > - tsz)) { > > + tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *ppos); > > + if (copy_to_iter((char *)phdrs + *ppos - phdrs_offset, tsz, > > + iter) != tsz) { > > kfree(phdrs); > > ret = -EFAULT; > > goto out; > > } > > kfree(phdrs); > > > > - buffer += tsz; > > buflen -= tsz; > > - *fpos += tsz; > > + *ppos += tsz; > > } > > > > /* ELF note segment. */ > > - if (buflen && *fpos < notes_offset + notes_len) { > > + if (buflen && *ppos < notes_offset + notes_len) { > > struct elf_prstatus prstatus = {}; > > struct elf_prpsinfo prpsinfo = { > > .pr_sname = 'R', > > @@ -447,24 +449,23 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > vmcoreinfo_data, > > min(vmcoreinfo_size, notes_len - i)); > > > > - tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); > > - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { > > + tsz = min_t(size_t, buflen, notes_offset + notes_len - *ppos); > > + if (copy_to_iter(notes + *ppos - notes_offset, tsz, iter) != tsz) { > > kfree(notes); > > ret = -EFAULT; > > goto out; > > } > > kfree(notes); > > > > - buffer += tsz; > > buflen -= tsz; > > - *fpos += tsz; > > + *ppos += tsz; > > } > > > > /* > > * Check to see if our file offset matches with any of > > * the addresses in the elf_phdr on our list. > > */ > > - start = kc_offset_to_vaddr(*fpos - data_offset); > > + start = kc_offset_to_vaddr(*ppos - data_offset); > > if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) > > tsz = buflen; > > > > @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > } > > > > if (!m) { > > - if (clear_user(buffer, tsz)) { > > + if (iov_iter_zero(tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > case KCORE_VMALLOC: > > vread(buf, (char *)start, tsz); > > /* we have to zero-fill user buffer even if no read */ > > - if (copy_to_user(buffer, buf, tsz)) { > > + if (copy_to_iter(buf, tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > break; > > case KCORE_USER: > > /* User page is handled prior to normal kernel page: */ > > - if (copy_to_user(buffer, (char *)start, tsz)) { > > + if (copy_to_iter((char *)start, tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > */ > > if (!page || PageOffline(page) || > > is_page_hwpoison(page) || !pfn_is_ram(pfn)) { > > - if (clear_user(buffer, tsz)) { > > + if (iov_iter_zero(tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > @@ -541,25 +542,24 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > case KCORE_VMEMMAP: > > case KCORE_TEXT: > > /* > > - * We use _copy_to_user() to bypass usermode hardening > > + * We use _copy_to_iter() to bypass usermode hardening > > * which would otherwise prevent this operation. > > */ > > - if (_copy_to_user(buffer, (char *)start, tsz)) { > > + if (_copy_to_iter((char *)start, tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > break; > > default: > > pr_warn_once("Unhandled KCORE type: %d\n", m->type); > > - if (clear_user(buffer, tsz)) { > > + if (iov_iter_zero(tsz, iter) != tsz) { > > ret = -EFAULT; > > goto out; > > } > > } > > skip: > > buflen -= tsz; > > - *fpos += tsz; > > - buffer += tsz; > > + *ppos += tsz; > > start += tsz; > > tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); > > } > > @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct file *file) > > } > > > > static const struct proc_ops kcore_proc_ops = { > > - .proc_read = read_kcore, > > + .proc_read_iter = read_kcore_iter, > > .proc_open = open_kcore, > > .proc_release = release_kcore, > > .proc_lseek = default_llseek, > > -- > > 2.39.2 > > >
On 21.03.23 21:54, Lorenzo Stoakes wrote: > Now we have eliminated spinlocks from the vread() case, convert > read_kcore() to read_kcore_iter(). > > For the time being we still use a bounce buffer for vread(), however in the > next patch we will convert this to interact directly with the iterator and > eliminate the bounce buffer altogether. > > Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> > --- > fs/proc/kcore.c | 58 ++++++++++++++++++++++++------------------------- > 1 file changed, 29 insertions(+), 29 deletions(-) > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index 556f310d6aa4..25e0eeb8d498 100644 > --- a/fs/proc/kcore.c > +++ b/fs/proc/kcore.c > @@ -24,7 +24,7 @@ > #include <linux/memblock.h> > #include <linux/init.h> > #include <linux/slab.h> > -#include <linux/uaccess.h> > +#include <linux/uio.h> > #include <asm/io.h> > #include <linux/list.h> > #include <linux/ioport.h> > @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, > } > > static ssize_t > -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) > { > + struct file *file = iocb->ki_filp; > char *buf = file->private_data; > + loff_t *ppos = &iocb->ki_pos; Not renaming fpos -> ppos in this patch would result in less noise in this patch. Just like you didn't rename buflen. In general, LGTM Reviewed-by: David Hildenbrand <david@redhat.com>
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 556f310d6aa4..25e0eeb8d498 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -24,7 +24,7 @@ #include <linux/memblock.h> #include <linux/init.h> #include <linux/slab.h> -#include <linux/uaccess.h> +#include <linux/uio.h> #include <asm/io.h> #include <linux/list.h> #include <linux/ioport.h> @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, } static ssize_t -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { + struct file *file = iocb->ki_filp; char *buf = file->private_data; + loff_t *ppos = &iocb->ki_pos; + size_t phdrs_offset, notes_offset, data_offset; size_t page_offline_frozen = 1; size_t phdrs_len, notes_len; @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) size_t tsz; int nphdr; unsigned long start; + size_t buflen = iov_iter_count(iter); size_t orig_buflen = buflen; int ret = 0; @@ -333,7 +337,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) notes_offset = phdrs_offset + phdrs_len; /* ELF file header. */ - if (buflen && *fpos < sizeof(struct elfhdr)) { + if (buflen && *ppos < sizeof(struct elfhdr)) { struct elfhdr ehdr = { .e_ident = { [EI_MAG0] = ELFMAG0, @@ -355,19 +359,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) .e_phnum = nphdr, }; - tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { + tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *ppos); + if (copy_to_iter((char *)&ehdr + *ppos, tsz, iter) != tsz) { ret = -EFAULT; goto out; } - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* ELF program headers. */ - if (buflen && *fpos < phdrs_offset + phdrs_len) { + if (buflen && *ppos < phdrs_offset + phdrs_len) { struct elf_phdr *phdrs, *phdr; phdrs = kzalloc(phdrs_len, GFP_KERNEL); @@ -397,22 +400,21 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) phdr++; } - tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, - tsz)) { + tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *ppos); + if (copy_to_iter((char *)phdrs + *ppos - phdrs_offset, tsz, + iter) != tsz) { kfree(phdrs); ret = -EFAULT; goto out; } kfree(phdrs); - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* ELF note segment. */ - if (buflen && *fpos < notes_offset + notes_len) { + if (buflen && *ppos < notes_offset + notes_len) { struct elf_prstatus prstatus = {}; struct elf_prpsinfo prpsinfo = { .pr_sname = 'R', @@ -447,24 +449,23 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) vmcoreinfo_data, min(vmcoreinfo_size, notes_len - i)); - tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { + tsz = min_t(size_t, buflen, notes_offset + notes_len - *ppos); + if (copy_to_iter(notes + *ppos - notes_offset, tsz, iter) != tsz) { kfree(notes); ret = -EFAULT; goto out; } kfree(notes); - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* * Check to see if our file offset matches with any of * the addresses in the elf_phdr on our list. */ - start = kc_offset_to_vaddr(*fpos - data_offset); + start = kc_offset_to_vaddr(*ppos - data_offset); if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) } if (!m) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMALLOC: vread(buf, (char *)start, tsz); /* we have to zero-fill user buffer even if no read */ - if (copy_to_user(buffer, buf, tsz)) { + if (copy_to_iter(buf, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; case KCORE_USER: /* User page is handled prior to normal kernel page: */ - if (copy_to_user(buffer, (char *)start, tsz)) { + if (copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) */ if (!page || PageOffline(page) || is_page_hwpoison(page) || !pfn_is_ram(pfn)) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -541,25 +542,24 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMEMMAP: case KCORE_TEXT: /* - * We use _copy_to_user() to bypass usermode hardening + * We use _copy_to_iter() to bypass usermode hardening * which would otherwise prevent this operation. */ - if (_copy_to_user(buffer, (char *)start, tsz)) { + if (_copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; default: pr_warn_once("Unhandled KCORE type: %d\n", m->type); - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } } skip: buflen -= tsz; - *fpos += tsz; - buffer += tsz; + *ppos += tsz; start += tsz; tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct file *file) } static const struct proc_ops kcore_proc_ops = { - .proc_read = read_kcore, + .proc_read_iter = read_kcore_iter, .proc_open = open_kcore, .proc_release = release_kcore, .proc_lseek = default_llseek,
Now we have eliminated spinlocks from the vread() case, convert read_kcore() to read_kcore_iter(). For the time being we still use a bounce buffer for vread(), however in the next patch we will convert this to interact directly with the iterator and eliminate the bounce buffer altogether. Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> --- fs/proc/kcore.c | 58 ++++++++++++++++++++++++------------------------- 1 file changed, 29 insertions(+), 29 deletions(-)