[PATCH 1/3] s390/kernel: add system calls for access PCI memory

[Alexey Ishchuk <aishchuk-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

Add the new __NR_s390_pci_mmio_write and __NR_s390_pci_mmio_read
system calls to allow user space applications to access device PCI I/O
memory pages on s390x platform.

Signed-off-by: Alexey Ishchuk <alexey_ishchuk-JgLE2wv1ufrQT0dZR+AlfA@public.gmane.org>
---
 arch/s390/include/uapi/asm/unistd.h |   4 +-
 arch/s390/kernel/Makefile           |   1 +
 arch/s390/kernel/entry.h            |   4 +
 arch/s390/kernel/pci_mmio.c         | 207 ++++++++++++++++++++++++++++++++++++
 arch/s390/kernel/syscalls.S         |   2 +
 5 files changed, 217 insertions(+), 1 deletion(-)
 create mode 100644 arch/s390/kernel/pci_mmio.c

diff --git a/arch/s390/include/uapi/asm/unistd.h b/arch/s390/include/uapi/asm/unistd.h
index 3802d2d..ab49d1d 100644
--- a/arch/s390/include/uapi/asm/unistd.h
+++ b/arch/s390/include/uapi/asm/unistd.h
@@ -283,7 +283,9 @@
 #define __NR_sched_setattr	345
 #define __NR_sched_getattr	346
 #define __NR_renameat2		347
-#define NR_syscalls 348
+#define __NR_s390_pci_mmio_write	348
+#define __NR_s390_pci_mmio_read		349
+#define NR_syscalls 350
 
 /* 
  * There are some system calls that are not present on 64 bit, some
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 33225e8..3e71b7e 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -60,6 +60,7 @@ ifdef CONFIG_64BIT
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf.o perf_cpum_sf.o \
 						perf_cpum_cf_events.o
 obj-y				+= runtime_instr.o cache.o
+obj-y				+= pci_mmio.o
 endif
 
 # vdso
diff --git a/arch/s390/kernel/entry.h b/arch/s390/kernel/entry.h
index 6ac7819..a36b6f9 100644
--- a/arch/s390/kernel/entry.h
+++ b/arch/s390/kernel/entry.h
@@ -70,4 +70,8 @@ struct old_sigaction;
 long sys_s390_personality(unsigned int personality);
 long sys_s390_runtime_instr(int command, int signum);
 
+long sys_s390_pci_mmio_write(const unsigned long mmio_addr,
+			     const void *user_buffer, const size_t length);
+long sys_s390_pci_mmio_read(const unsigned long mmio_addr,
+			    void *user_buffer, const size_t length);
 #endif /* _ENTRY_H */
diff --git a/arch/s390/kernel/pci_mmio.c b/arch/s390/kernel/pci_mmio.c
new file mode 100644
index 0000000..f318207
--- /dev/null
+++ b/arch/s390/kernel/pci_mmio.c
@@ -0,0 +1,207 @@
+/*
+ * Access to PCI I/O memory from user space programs.
+ *
+ * Copyright IBM Corp. 2014
+ * Author(s): Alexey Ishchuk <aishchuk-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
+ */
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/pci.h>
+
+union value_buffer {
+	u8 buf8;
+	u16 buf16;
+	u32 buf32;
+	u64 buf64;
+	u8 buf_large[64];
+};
+
+static long get_pfn(const unsigned long user_addr,
+		    const unsigned long access,
+		    unsigned long *pfn)
+{
+	struct vm_area_struct *vma = NULL;
+	long ret = 0L;
+
+	if (!pfn)
+		return -EINVAL;
+
+	down_read(&current->mm->mmap_sem);
+	vma = find_vma(current->mm, user_addr);
+	if (vma) {
+		if (!(vma->vm_flags & access))
+			ret = -EACCES;
+		else
+			ret = follow_pfn(vma, user_addr, pfn);
+	} else {
+		ret = -EINVAL;
+	}
+	up_read(&current->mm->mmap_sem);
+
+	return ret;
+}
+
+static inline int verify_page_addr(const unsigned long page_addr)
+{
+	return !(page_addr < ZPCI_IOMAP_ADDR_BASE ||
+	    page_addr > (ZPCI_IOMAP_ADDR_BASE | ZPCI_IOMAP_ADDR_IDX_MASK));
+}
+
+static long choose_buffer(const size_t length,
+			  union value_buffer *value,
+			  void **buf)
+{
+	long ret = 0L;
+
+	if (length > sizeof(value->buf_large)) {
+		*buf = kmalloc(length, GFP_KERNEL);
+		if (!*buf)
+			return -ENOMEM;
+		ret = 1;
+	} else {
+		*buf = value->buf_large;
+	}
+	return ret;
+}
+
+SYSCALL_DEFINE3(s390_pci_mmio_write,
+		const unsigned long, mmio_addr,
+		const void __user *, user_buffer,
+		const size_t, length)
+{
+	long ret = 0L;
+	void *buf = NULL;
+	long buf_allocated = 0;
+	void __iomem *io_addr = NULL;
+	unsigned long pfn = 0UL;
+	unsigned long offset = 0UL;
+	unsigned long page_addr = 0UL;
+	union value_buffer value;
+
+	if (!length)
+		return -EINVAL;
+	if (!zpci_is_enabled())
+		return -ENODEV;
+
+	ret = get_pfn(mmio_addr, VM_WRITE, &pfn);
+	if (ret)
+		return ret;
+
+	page_addr = pfn << PAGE_SHIFT;
+	if (!verify_page_addr(page_addr))
+		return -EFAULT;
+
+	offset = mmio_addr & ~PAGE_MASK;
+	if (offset + length > PAGE_SIZE)
+		return -EINVAL;
+	io_addr = (void *)(page_addr | offset);
+
+	buf_allocated = choose_buffer(length, &value, &buf);
+	if (buf_allocated < 0L)
+		return -ENOMEM;
+
+	switch (length) {
+	case 1:
+		ret = get_user(value.buf8, ((u8 *)user_buffer));
+		break;
+	case 2:
+		ret = get_user(value.buf16, ((u16 *)user_buffer));
+		break;
+	case 4:
+		ret = get_user(value.buf32, ((u32 *)user_buffer));
+		break;
+	case 8:
+		ret = get_user(value.buf64, ((u64 *)user_buffer));
+		break;
+	default:
+		ret = copy_from_user(buf, user_buffer, length);
+	}
+	if (ret)
+		goto out;
+
+	switch (length) {
+	case 1:
+		__raw_writeb(value.buf8, io_addr);
+		break;
+	case 2:
+		__raw_writew(value.buf16, io_addr);
+		break;
+	case 4:
+		__raw_writel(value.buf32, io_addr);
+		break;
+	case 8:
+		__raw_writeq(value.buf64, io_addr);
+		break;
+	default:
+		memcpy_toio(io_addr, buf, length);
+	}
+out:
+	if (buf_allocated > 0L)
+		kfree(buf);
+	return ret;
+}
+
+SYSCALL_DEFINE3(s390_pci_mmio_read,
+		const unsigned long, mmio_addr,
+		void __user *, user_buffer,
+		const size_t, length)
+{
+	long ret = 0L;
+	void *buf = NULL;
+	long buf_allocated = 0L;
+	void __iomem *io_addr = NULL;
+	unsigned long pfn = 0UL;
+	unsigned long offset = 0UL;
+	unsigned long page_addr = 0UL;
+	union value_buffer value;
+
+	if (!length)
+		return -EINVAL;
+	if (!zpci_is_enabled())
+		return -ENODEV;
+
+	ret = get_pfn(mmio_addr, VM_READ, &pfn);
+	if (ret)
+		return ret;
+
+	page_addr = pfn << PAGE_SHIFT;
+	if (!verify_page_addr(page_addr))
+		return -EFAULT;
+
+	offset = mmio_addr & ~PAGE_MASK;
+	if (offset + length > PAGE_SIZE)
+		return -EINVAL;
+	io_addr = (void *)(page_addr | offset);
+
+	buf_allocated = choose_buffer(length, &value, &buf);
+	if (buf_allocated < 0L)
+		return -ENOMEM;
+
+	switch (length) {
+	case 1:
+		value.buf8 = __raw_readb(io_addr);
+		ret = put_user(value.buf8, ((u8 *)user_buffer));
+		break;
+	case 2:
+		value.buf16 = __raw_readw(io_addr);
+		ret = put_user(value.buf16, ((u16 *)user_buffer));
+		break;
+	case 4:
+		value.buf32 = __raw_readl(io_addr);
+		ret = put_user(value.buf32, ((u32 *)user_buffer));
+		break;
+	case 8:
+		value.buf64 = __raw_readq(io_addr);
+		ret = put_user(value.buf64, ((u64 *)user_buffer));
+		break;
+	default:
+		memcpy_fromio(buf, io_addr, length);
+		ret = copy_to_user(user_buffer, buf, length);
+	}
+	if (buf_allocated > 0L)
+		kfree(buf);
+	return ret;
+}
diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index fe5cdf2..1faa942 100644
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -356,3 +356,5 @@ SYSCALL(sys_finit_module,sys_finit_module,compat_sys_finit_module)
 SYSCALL(sys_sched_setattr,sys_sched_setattr,compat_sys_sched_setattr) /* 345 */
 SYSCALL(sys_sched_getattr,sys_sched_getattr,compat_sys_sched_getattr)
 SYSCALL(sys_renameat2,sys_renameat2,compat_sys_renameat2)
+SYSCALL(sys_ni_syscall,sys_s390_pci_mmio_write,sys_ni_syscall)
+SYSCALL(sys_ni_syscall,sys_s390_pci_mmio_read,sys_ni_syscall)
-- 
1.8.5.5

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html