EDAC, skx, i10nm: Make skx_common.c a pure library

The following Kconfig constellations fail randconfig builds:

  CONFIG_ACPI_NFIT=y
  CONFIG_EDAC_DEBUG=y
  CONFIG_EDAC_SKX=m
  CONFIG_EDAC_I10NM=y

or

  CONFIG_ACPI_NFIT=y
  CONFIG_EDAC_DEBUG=y
  CONFIG_EDAC_SKX=y
  CONFIG_EDAC_I10NM=m

with:
  ...
  CC [M]  drivers/edac/skx_common.o
  ...
  .../skx_common.o:.../skx_common.c:672: undefined reference to `__this_module'

That is because if one of the two drivers - skx_edac or i10nm_edac - is
built-in and the other one is a module, the shared file skx_common.c
gets linked into a module object by kbuild. Therefore, when linking that
same file into vmlinux, the '__this_module' symbol used in debugfs isn't
defined, leading to the above error.

Fix it by moving all debugfs code from skx_common.c to both skx_base.c
and i10nm_base.c respectively. Thus, skx_common.c doesn't refer to the
'__this_module' symbol anymore.

Clarify skx_common.c's purpose at the top of the file for future
reference, while at it.

 [ bp: Make text more readable. ]

Fixes: d4dc89d069aa ("EDAC, i10nm: Add a driver for Intel 10nm server processors")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: https://lkml.kernel.org/r/20190321221339.GA32323@agluck-desk

1 files changed, 10 insertions, 47 deletions

diff --git a/drivers/edac/skx_common.c b/drivers/edac/skx_common.c
index 0e96e7b5b0a7..b0dddcfa9baa 100644
--- a/drivers/edac/skx_common.c
+++ b/drivers/edac/skx_common.c
@@ -1,7 +1,15 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Common codes for both the skx_edac driver and Intel 10nm server EDAC driver.
- * Originally split out from the skx_edac driver.
+ *
+ * Shared code by both skx_edac and i10nm_edac. Originally split out
+ * from the skx_edac driver.
+ *
+ * This file is linked into both skx_edac and i10nm_edac drivers. In
+ * order to avoid link errors, this file must be like a pure library
+ * without including symbols and defines which would otherwise conflict,
+ * when linked once into a module and into a built-in object, at the
+ * same time. For example, __this_module symbol references when that
+ * file is being linked into a built-in object.
  *
  * Copyright (c) 2018, Intel Corporation.
  */
@@ -644,48 +652,3 @@ void skx_remove(void)
 		kfree(d);
 	}
 }
-
-#ifdef CONFIG_EDAC_DEBUG
-/*
- * Debug feature.
- * Exercise the address decode logic by writing an address to
- * /sys/kernel/debug/edac/dirname/addr.
- */
-static struct dentry *skx_test;
-
-static int debugfs_u64_set(void *data, u64 val)
-{
-	struct mce m;
-
-	pr_warn_once("Fake error to 0x%llx injected via debugfs\n", val);
-
-	memset(&m, 0, sizeof(m));
-	/* ADDRV + MemRd + Unknown channel */
-	m.status = MCI_STATUS_ADDRV + 0x90;
-	/* One corrected error */
-	m.status |= BIT_ULL(MCI_STATUS_CEC_SHIFT);
-	m.addr = val;
-	skx_mce_check_error(NULL, 0, &m);
-
-	return 0;
-}
-DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");
-
-void setup_skx_debug(const char *dirname)
-{
-	skx_test = edac_debugfs_create_dir(dirname);
-	if (!skx_test)
-		return;
-
-	if (!edac_debugfs_create_file("addr", 0200, skx_test,
-				      NULL, &fops_u64_wo)) {
-		debugfs_remove(skx_test);
-		skx_test = NULL;
-	}
-}
-
-void teardown_skx_debug(void)
-{
-	debugfs_remove_recursive(skx_test);
-}
-#endif /*CONFIG_EDAC_DEBUG*/