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Subject[PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code
Date
Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
appear in generic kernel code because it forces non-x86 architectures to
define the sev_active() function, which doesn't make a lot of sense.

To solve this problem, add an x86 elfcorehdr_read() function to override
the generic weak implementation. To do that, it's necessary to make
read_from_oldmem() public so that it can be used outside of vmcore.c.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/x86/kernel/crash_dump_64.c | 5 +++++
fs/proc/vmcore.c | 8 ++++----
include/linux/crash_dump.h | 14 ++++++++++++++
include/linux/mem_encrypt.h | 1 -
4 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index 22369dd5de3b..045e82e8945b 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -70,3 +70,8 @@ ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
{
return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
}
+
+ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
+{
+ return read_from_oldmem(buf, count, ppos, 0, sev_active());
+}
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 57957c91c6df..ca1f20bedd8c 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -100,9 +100,9 @@ static int pfn_is_ram(unsigned long pfn)
}

/* Reads a page from the oldmem device from given offset. */
-static ssize_t read_from_oldmem(char *buf, size_t count,
- u64 *ppos, int userbuf,
- bool encrypted)
+ssize_t read_from_oldmem(char *buf, size_t count,
+ u64 *ppos, int userbuf,
+ bool encrypted)
{
unsigned long pfn, offset;
size_t nr_bytes;
@@ -166,7 +166,7 @@ void __weak elfcorehdr_free(unsigned long long addr)
*/
ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
- return read_from_oldmem(buf, count, ppos, 0, sev_active());
+ return read_from_oldmem(buf, count, ppos, 0, false);
}

/*
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index f774c5eb9e3c..4664fc1871de 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -115,4 +115,18 @@ static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
return -EOPNOTSUPP;
}
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
+
+#ifdef CONFIG_PROC_VMCORE
+ssize_t read_from_oldmem(char *buf, size_t count,
+ u64 *ppos, int userbuf,
+ bool encrypted);
+#else
+static inline ssize_t read_from_oldmem(char *buf, size_t count,
+ u64 *ppos, int userbuf,
+ bool encrypted)
+{
+ return -EOPNOTSUPP;
+}
+#endif /* CONFIG_PROC_VMCORE */
+
#endif /* LINUX_CRASHDUMP_H */
diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
index f2e399fb626b..a3747fcae466 100644
--- a/include/linux/mem_encrypt.h
+++ b/include/linux/mem_encrypt.h
@@ -21,7 +21,6 @@

#else /* !CONFIG_ARCH_HAS_MEM_ENCRYPT */

-static inline bool sev_active(void) { return false; }
static inline bool mem_encrypt_active(void) { return false; }

#endif /* CONFIG_ARCH_HAS_MEM_ENCRYPT */
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