char: sparc64: Add privileged ADI driver (873c38a4) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/char/Kconfig

+12 −0

Original line number	Diff line number	Diff line
		@@ -540,5 +540,17 @@ source "drivers/s390/char/Kconfig"

		source "drivers/char/xillybus/Kconfig"

		config ADI
		tristate "SPARC Privileged ADI driver"
		depends on SPARC64
		default m
		help
		SPARC M7 and newer processors utilize ADI (Application Data
		Integrity) to version and protect memory. This driver provides
		read/write access to the ADI versions for privileged processes.
		This feature is also known as MCD (Memory Corruption Detection)
		and SSM (Silicon Secured Memory). Intended consumers of this
		driver include crash and makedumpfile.

		endmenu

drivers/char/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -57,3 +57,4 @@ js-rtc-y = rtc.o

		obj-$(CONFIG_XILLYBUS) += xillybus/
		obj-$(CONFIG_POWERNV_OP_PANEL) += powernv-op-panel.o
		obj-$(CONFIG_ADI) += adi.o

drivers/char/adi.c

0 → 100644

+239 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/*
		* Privileged ADI driver for sparc64
		*
		* Author: Tom Hromatka <tom.hromatka@oracle.com>
		*/
		#include <linux/kernel.h>
		#include <linux/miscdevice.h>
		#include <linux/module.h>
		#include <linux/proc_fs.h>
		#include <linux/slab.h>
		#include <linux/uaccess.h>
		#include <asm/asi.h>

		#define MAX_BUF_SZ PAGE_SIZE

		static int adi_open(struct inode inode, struct file file)
		{
		file->f_mode \|= FMODE_UNSIGNED_OFFSET;
		return 0;
		}

		static int read_mcd_tag(unsigned long addr)
		{
		long err;
		int ver;

		__asm__ __volatile__(
		"1: ldxa [%[addr]] %[asi], %[ver]\n"
		" mov 0, %[err]\n"
		"2:\n"
		" .section .fixup,#alloc,#execinstr\n"
		" .align 4\n"
		"3: sethi %%hi(2b), %%g1\n"
		" jmpl %%g1 + %%lo(2b), %%g0\n"
		" mov %[invalid], %[err]\n"
		" .previous\n"
		" .section __ex_table, \"a\"\n"
		" .align 4\n"
		" .word 1b, 3b\n"
		" .previous\n"
		: [ver] "=r" (ver), [err] "=r" (err)
		: [addr] "r" (addr), [invalid] "i" (EFAULT),
		[asi] "i" (ASI_MCD_REAL)
		: "memory", "g1"
		);

		if (err)
		return -EFAULT;
		else
		return ver;
		}

		static ssize_t adi_read(struct file file, char __user buf,
		size_t count, loff_t *offp)
		{
		size_t ver_buf_sz, bytes_read = 0;
		int ver_buf_idx = 0;
		loff_t offset;
		u8 *ver_buf;
		ssize_t ret;

		ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
		ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
		if (!ver_buf)
		return -ENOMEM;

		offset = (offp) adi_blksize();

		while (bytes_read < count) {
		ret = read_mcd_tag(offset);
		if (ret < 0)
		goto out;

		ver_buf[ver_buf_idx] = (u8)ret;
		ver_buf_idx++;
		offset += adi_blksize();

		if (ver_buf_idx >= ver_buf_sz) {
		if (copy_to_user(buf + bytes_read, ver_buf,
		ver_buf_sz)) {
		ret = -EFAULT;
		goto out;
		}

		bytes_read += ver_buf_sz;
		ver_buf_idx = 0;

		ver_buf_sz = min(count - bytes_read,
		(size_t)MAX_BUF_SZ);
		}
		}

		(*offp) += bytes_read;
		ret = bytes_read;
		out:
		kfree(ver_buf);
		return ret;
		}

		static int set_mcd_tag(unsigned long addr, u8 ver)
		{
		long err;

		__asm__ __volatile__(
		"1: stxa %[ver], [%[addr]] %[asi]\n"
		" mov 0, %[err]\n"
		"2:\n"
		" .section .fixup,#alloc,#execinstr\n"
		" .align 4\n"
		"3: sethi %%hi(2b), %%g1\n"
		" jmpl %%g1 + %%lo(2b), %%g0\n"
		" mov %[invalid], %[err]\n"
		" .previous\n"
		" .section __ex_table, \"a\"\n"
		" .align 4\n"
		" .word 1b, 3b\n"
		" .previous\n"
		: [err] "=r" (err)
		: [ver] "r" (ver), [addr] "r" (addr),
		[invalid] "i" (EFAULT), [asi] "i" (ASI_MCD_REAL)
		: "memory", "g1"
		);

		if (err)
		return -EFAULT;
		else
		return ver;
		}

		static ssize_t adi_write(struct file file, const char __user buf,
		size_t count, loff_t *offp)
		{
		size_t ver_buf_sz, bytes_written = 0;
		loff_t offset;
		u8 *ver_buf;
		ssize_t ret;
		int i;

		if (count <= 0)
		return -EINVAL;

		ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
		ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
		if (!ver_buf)
		return -ENOMEM;

		offset = (offp) adi_blksize();

		do {
		if (copy_from_user(ver_buf, &buf[bytes_written],
		ver_buf_sz)) {
		ret = -EFAULT;
		goto out;
		}

		for (i = 0; i < ver_buf_sz; i++) {
		ret = set_mcd_tag(offset, ver_buf[i]);
		if (ret < 0)
		goto out;

		offset += adi_blksize();
		}

		bytes_written += ver_buf_sz;
		ver_buf_sz = min(count - bytes_written, (size_t)MAX_BUF_SZ);
		} while (bytes_written < count);

		(*offp) += bytes_written;
		ret = bytes_written;
		out:
		__asm__ __volatile__("membar #Sync");
		kfree(ver_buf);
		return ret;
		}

		static loff_t adi_llseek(struct file *file, loff_t offset, int whence)
		{
		loff_t ret = -EINVAL;

		switch (whence) {
		case SEEK_END:
		case SEEK_DATA:
		case SEEK_HOLE:
		/* unsupported */
		return -EINVAL;
		case SEEK_CUR:
		if (offset == 0)
		return file->f_pos;

		offset += file->f_pos;
		break;
		case SEEK_SET:
		break;
		}

		if (offset != file->f_pos) {
		file->f_pos = offset;
		file->f_version = 0;
		ret = offset;
		}

		return ret;
		}

		static const struct file_operations adi_fops = {
		.owner = THIS_MODULE,
		.llseek = adi_llseek,
		.open = adi_open,
		.read = adi_read,
		.write = adi_write,
		};

		static struct miscdevice adi_miscdev = {
		.minor = MISC_DYNAMIC_MINOR,
		.name = KBUILD_MODNAME,
		.fops = &adi_fops,
		};

		static int __init adi_init(void)
		{
		if (!adi_capable())
		return -EPERM;

		return misc_register(&adi_miscdev);
		}

		static void __exit adi_exit(void)
		{
		misc_deregister(&adi_miscdev);
		}

		module_init(adi_init);
		module_exit(adi_exit);

		MODULE_AUTHOR("Tom Hromatka <tom.hromatka@oracle.com>");
		MODULE_DESCRIPTION("Privileged interface to ADI");
		MODULE_VERSION("1.0");
		MODULE_LICENSE("GPL v2");