[PATCH 1/3] vmcore: Convert copy_oldmem_page() to take an iov_iter
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: 2021-12-13 00:06:52
Also in:
kexec, linux-s390, lkml
Subsystem:
arm port, arm64 port (aarch64 architecture), filesystems (vfs and infrastructure), kdump, linux for powerpc (32-bit and 64-bit), mips, proc filesystem, risc-v architecture, s390 architecture, superh, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Russell King, Catalin Marinas, Will Deacon, Alexander Viro, Christian Brauner, Andrew Morton, Baoquan He, Mike Rapoport, Pasha Tatashin, Pratyush Yadav, Madhavan Srinivasan, Michael Ellerman, Thomas Bogendoerfer, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Instead of passing in a 'buf' and 'userbuf' argument, pass in an iov_iter. s390 needs more work to pass the iov_iter down further, or refactor, but I'd be more comfortable if someone who can test on s390 did that work. It's more convenient to convert the whole of read_from_oldmem() to take an iov_iter at the same time, so rename it to read_from_oldmem_iter() and add a temporary read_from_oldmem() wrapper that creates an iov_iter. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- arch/arm/kernel/crash_dump.c | 14 ++------- arch/arm64/kernel/crash_dump.c | 14 ++------- arch/ia64/kernel/crash_dump.c | 12 ++------ arch/mips/kernel/crash_dump.c | 13 ++------ arch/powerpc/kernel/crash_dump.c | 20 +++--------- arch/riscv/kernel/crash_dump.c | 13 ++------ arch/s390/kernel/crash_dump.c | 12 +++++--- arch/sh/kernel/crash_dump.c | 15 +++------ arch/x86/kernel/crash_dump_32.c | 13 ++------ arch/x86/kernel/crash_dump_64.c | 24 ++++++--------- fs/proc/vmcore.c | 53 ++++++++++++++++++++------------ include/linux/crash_dump.h | 9 +++--- 12 files changed, 79 insertions(+), 133 deletions(-)
diff --git a/arch/arm/kernel/crash_dump.c b/arch/arm/kernel/crash_dump.c
index 53cb92435392..15d7db782f24 100644
--- a/arch/arm/kernel/crash_dump.c
+++ b/arch/arm/kernel/crash_dump.c@@ -27,9 +27,8 @@ * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes * copied or negative error in case of failure. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, - int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr;
@@ -40,14 +39,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (!vaddr) return -ENOMEM; - if (userbuf) { - if (copy_to_user(buf, vaddr + offset, csize)) { - iounmap(vaddr); - return -EFAULT; - } - } else { - memcpy(buf, vaddr + offset, csize); - } + csize = copy_to_iter(vaddr + offset, csize, iter); iounmap(vaddr); return csize;
diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c
index 58303a9ec32c..991d30aac439 100644
--- a/arch/arm64/kernel/crash_dump.c
+++ b/arch/arm64/kernel/crash_dump.c@@ -25,9 +25,8 @@ * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes * copied or negative error in case of failure. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, - int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr;
@@ -38,14 +37,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (!vaddr) return -ENOMEM; - if (userbuf) { - if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { - memunmap(vaddr); - return -EFAULT; - } - } else { - memcpy(buf, vaddr + offset, csize); - } + csize = copy_to_iter(vaddr + offset, csize, iter); memunmap(vaddr);
diff --git a/arch/ia64/kernel/crash_dump.c b/arch/ia64/kernel/crash_dump.c
index 0ed3c3dee4cd..bc331272bbd6 100644
--- a/arch/ia64/kernel/crash_dump.c
+++ b/arch/ia64/kernel/crash_dump.c@@ -31,21 +31,15 @@ * copying the data to a pre-allocated kernel page and then copying to user * space in non-atomic context. */ -ssize_t -copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr; if (!csize) return 0; vaddr = __va(pfn<<PAGE_SHIFT); - if (userbuf) { - if (copy_to_user(buf, (vaddr + offset), csize)) { - return -EFAULT; - } - } else - memcpy(buf, (vaddr + offset), csize); + csize = copy_to_iter(vaddr + offset, csize, iter); return csize; }
diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
index 2e50f55185a6..926665c798b6 100644
--- a/arch/mips/kernel/crash_dump.c
+++ b/arch/mips/kernel/crash_dump.c@@ -15,8 +15,8 @@ * Copy a page from "oldmem". For this page, there is no pte mapped * in the current kernel. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr;
@@ -24,14 +24,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, return 0; vaddr = kmap_local_pfn(pfn); - - if (!userbuf) { - memcpy(buf, vaddr + offset, csize); - } else { - if (copy_to_user(buf, vaddr + offset, csize)) - csize = -EFAULT; - } - + csize = copy_to_iter(vaddr + offset, csize, iter); kunmap_local(vaddr); return csize;
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 5693e1c67c2b..541bcc01490c 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c@@ -68,18 +68,6 @@ void __init setup_kdump_trampoline(void) } #endif /* CONFIG_NONSTATIC_KERNEL */ -static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, - unsigned long offset, int userbuf) -{ - if (userbuf) { - if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) - return -EFAULT; - } else - memcpy(buf, (vaddr + offset), csize); - - return csize; -} - /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied
@@ -93,8 +81,8 @@ static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, * Copy a page from "oldmem". For this page, there is no pte mapped * in the current kernel. We stitch up a pte, similar to kmap_atomic. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr; phys_addr_t paddr;
@@ -107,10 +95,10 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (memblock_is_region_memory(paddr, csize)) { vaddr = __va(paddr); - csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); + csize = copy_to_iter(vaddr + offset, csize, iter); } else { vaddr = ioremap_cache(paddr, PAGE_SIZE); - csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); + csize = copy_to_iter(vaddr + offset, csize, iter); iounmap(vaddr); }
diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c
index 86cc0ada5752..f4dffb8c7eb7 100644
--- a/arch/riscv/kernel/crash_dump.c
+++ b/arch/riscv/kernel/crash_dump.c@@ -20,9 +20,8 @@ * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes * copied or negative error in case of failure. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, - int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void *vaddr;
@@ -33,13 +32,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (!vaddr) return -ENOMEM; - if (userbuf) { - if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { - memunmap(vaddr); - return -EFAULT; - } - } else - memcpy(buf, vaddr + offset, csize); + csize = copy_to_iter(vaddr + offset, csize, iter); memunmap(vaddr); return csize;
diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 785d54c9350c..09bf559f2c5b 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c@@ -214,8 +214,8 @@ static int copy_oldmem_user(void __user *dst, void *src, size_t count) /* * Copy one page from "oldmem" */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize, + unsigned long offset) { void *src; int rc;
@@ -223,10 +223,12 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, if (!csize) return 0; src = (void *) (pfn << PAGE_SHIFT) + offset; - if (userbuf) - rc = copy_oldmem_user((void __force __user *) buf, src, csize); + + /* XXX: pass the iov_iter down to a common function */ + if (iter_is_iovec(iter)) + rc = copy_oldmem_user(iter->iov->iov_base, src, csize); else - rc = copy_oldmem_kernel((void *) buf, src, csize); + rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize); return rc; }
diff --git a/arch/sh/kernel/crash_dump.c b/arch/sh/kernel/crash_dump.c
index 5b41b59698c1..26081861cb62 100644
--- a/arch/sh/kernel/crash_dump.c
+++ b/arch/sh/kernel/crash_dump.c@@ -23,8 +23,8 @@ * Copy a page from "oldmem". For this page, there is no pte mapped * in the current kernel. We stitch up a pte, similar to kmap_atomic. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { void __iomem *vaddr;
@@ -32,15 +32,8 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, return 0; vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); - - if (userbuf) { - if (copy_to_user((void __user *)buf, (vaddr + offset), csize)) { - iounmap(vaddr); - return -EFAULT; - } - } else - memcpy(buf, (vaddr + offset), csize); - + csize = copy_to_iter(vaddr + offset, csize, iter); iounmap(vaddr); + return csize; }
diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index 5fcac46aaf6b..23d38ecf5de2 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c@@ -42,8 +42,8 @@ static inline bool is_crashed_pfn_valid(unsigned long pfn) * Copy a page from "oldmem". For this page, there might be no pte mapped * in the current kernel. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize, + unsigned long offset) { void *vaddr;
@@ -54,14 +54,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, return -EFAULT; vaddr = kmap_local_pfn(pfn); - - if (!userbuf) { - memcpy(buf, vaddr + offset, csize); - } else { - if (copy_to_user(buf, vaddr + offset, csize)) - csize = -EFAULT; - } - + csize = copy_to_iter(vaddr + offset, csize, iter); kunmap_local(vaddr); return csize;
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index a7f617a3981d..8d91e5f2e14d 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c@@ -12,8 +12,8 @@ #include <linux/io.h> #include <linux/cc_platform.h> -static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf, +static ssize_t __copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset, bool encrypted) { void *vaddr;
@@ -29,13 +29,7 @@ static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, if (!vaddr) return -ENOMEM; - if (userbuf) { - if (copy_to_user((void __user *)buf, vaddr + offset, csize)) { - iounmap((void __iomem *)vaddr); - return -EFAULT; - } - } else - memcpy(buf, vaddr + offset, csize); + csize = copy_to_iter(vaddr + offset, csize, iter); set_iounmap_nonlazy(); iounmap((void __iomem *)vaddr);
@@ -55,10 +49,10 @@ static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, * Copy a page from the old kernel's memory. For this page, there is no pte * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize, + unsigned long offset) { - return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false); + return __copy_oldmem_page(iter, pfn, csize, offset, false); } /**
@@ -66,10 +60,10 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, * memory with the encryption mask set to accommodate kdump on SME-enabled * machines. */ -ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf) +ssize_t copy_oldmem_page_encrypted(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) { - return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true); + return __copy_oldmem_page(iter, pfn, csize, offset, true); } ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 509f85148fee..049bafe9c007 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c@@ -132,9 +132,8 @@ static int open_vmcore(struct inode *inode, struct file *file) } /* Reads a page from the oldmem device from given offset. */ -ssize_t read_from_oldmem(char *buf, size_t count, - u64 *ppos, int userbuf, - bool encrypted) +ssize_t read_from_oldmem_iter(struct iov_iter *iter, size_t count, + u64 *ppos, bool encrypted) { unsigned long pfn, offset; size_t nr_bytes;
@@ -155,29 +154,23 @@ ssize_t read_from_oldmem(char *buf, size_t count, /* If pfn is not ram, return zeros for sparse dump files */ if (!pfn_is_ram(pfn)) { - tmp = 0; - if (!userbuf) - memset(buf, 0, nr_bytes); - else if (clear_user(buf, nr_bytes)) - tmp = -EFAULT; + tmp = iov_iter_zero(nr_bytes, iter); } else { if (encrypted) - tmp = copy_oldmem_page_encrypted(pfn, buf, + tmp = copy_oldmem_page_encrypted(iter, pfn, nr_bytes, - offset, - userbuf); + offset); else - tmp = copy_oldmem_page(pfn, buf, nr_bytes, - offset, userbuf); + tmp = copy_oldmem_page(iter, pfn, nr_bytes, + offset); } - if (tmp < 0) { + if (tmp < nr_bytes) { up_read(&vmcore_cb_rwsem); - return tmp; + return -EFAULT; } *ppos += nr_bytes; count -= nr_bytes; - buf += nr_bytes; read += nr_bytes; ++pfn; offset = 0;
@@ -187,6 +180,27 @@ ssize_t read_from_oldmem(char *buf, size_t count, return read; } +ssize_t read_from_oldmem(char *buf, size_t count, + u64 *ppos, int userbuf, + bool encrypted) +{ + struct iov_iter iter; + struct iovec iov; + struct kvec kvec; + + if (userbuf) { + iov.iov_base = (__force void __user *)buf; + iov.iov_len = count; + iov_iter_init(&iter, READ, &iov, 1, count); + } else { + kvec.iov_base = buf; + kvec.iov_len = count; + iov_iter_kvec(&iter, READ, &kvec, 1, count); + } + + return read_from_oldmem_iter(&iter, count, ppos, encrypted); +} + /* * Architectures may override this function to allocate ELF header in 2nd kernel */
@@ -231,11 +245,10 @@ int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma, /* * Architectures which support memory encryption override this. */ -ssize_t __weak -copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize, - unsigned long offset, int userbuf) +ssize_t __weak copy_oldmem_page_encrypted(struct iov_iter *iter, + unsigned long pfn, size_t csize, unsigned long offset) { - return copy_oldmem_page(pfn, buf, csize, offset, userbuf); + return copy_oldmem_page(iter, pfn, csize, offset); } /*
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 620821549b23..a1cf7d5c03c7 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h@@ -24,11 +24,10 @@ extern int remap_oldmem_pfn_range(struct vm_area_struct *vma, unsigned long from, unsigned long pfn, unsigned long size, pgprot_t prot); -extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, - unsigned long, int); -extern ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, - int userbuf); +ssize_t copy_oldmem_page(struct iov_iter *i, unsigned long pfn, size_t csize, + unsigned long offset); +ssize_t copy_oldmem_page_encrypted(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset); void vmcore_cleanup(void);
--
2.33.0