[tip: ras/core] x86/mce: Provide method to find out the type of an exception handler

tip-bot2 for Tony Luck
2020-10-07T10:03:12Z

The following commit has been merged into the ras/core branch of tip:

Commit-ID: a05d54c41ecfa1a322b229b4e5ce50c157284f74
Gitweb: https://git.kernel.org/tip/a05d54c41ecfa1a322b229b4e5ce50c157284f74
Author: Tony Luck <tony.luck@intel.com>
AuthorDate: Tue, 06 Oct 2020 14:09:06 -07:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 07 Oct 2020 11:08:59 +02:00

x86/mce: Provide method to find out the type of an exception handler

Avoid a proliferation of ex_has_*_handler() functions by having just
one function that returns the type of the handler (if any).

Drop the __visible attribute for this function. It is not called
from assembler so the attribute is not necessary.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201006210910.21062-3-tony.luck@intel.com
---
arch/x86/include/asm/extable.h | 9 ++++++++-
arch/x86/kernel/cpu/mce/severity.c | 5 ++++-
arch/x86/mm/extable.c | 12 ++++++++----
3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/extable.h b/arch/x86/include/asm/extable.h
index d8c2198..1f0cbc5 100644
--- a/arch/x86/include/asm/extable.h
+++ b/arch/x86/include/asm/extable.h
@@ -29,10 +29,17 @@ struct pt_regs;
(b)->handler = (tmp).handler - (delta); \
} while (0)

+enum handler_type {
+ EX_HANDLER_NONE,
+ EX_HANDLER_FAULT,
+ EX_HANDLER_UACCESS,
+ EX_HANDLER_OTHER
+};
+
extern int fixup_exception(struct pt_regs *regs, int trapnr,
unsigned long error_code, unsigned long fault_addr);
extern int fixup_bug(struct pt_regs *regs, int trapnr);
-extern bool ex_has_fault_handler(unsigned long ip);
+extern enum handler_type ex_get_fault_handler_type(unsigned long ip);
extern void early_fixup_exception(struct pt_regs *regs, int trapnr);

#endif
diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index 0b072dc..c6494e6 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -225,10 +225,13 @@ static struct severity {
*/
static int error_context(struct mce *m, struct pt_regs *regs)
{
+ enum handler_type t;
+
if ((m->cs & 3) == 3)
return IN_USER;

- if (mc_recoverable(m->mcgstatus) && ex_has_fault_handler(m->ip)) {
+ t = ex_get_fault_handler_type(m->ip);
+ if (mc_recoverable(m->mcgstatus) && t == EX_HANDLER_FAULT) {
m->kflags |= MCE_IN_KERNEL_RECOV;
return IN_KERNEL_RECOV;
}
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 1d6cb07..de43525 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -125,17 +125,21 @@ __visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
}
EXPORT_SYMBOL(ex_handler_clear_fs);

-__visible bool ex_has_fault_handler(unsigned long ip)
+enum handler_type ex_get_fault_handler_type(unsigned long ip)
{
const struct exception_table_entry *e;
ex_handler_t handler;

e = search_exception_tables(ip);
if (!e)
- return false;
+ return EX_HANDLER_NONE;
handler = ex_fixup_handler(e);
-
- return handler == ex_handler_fault;
+ if (handler == ex_handler_fault)
+ return EX_HANDLER_FAULT;
+ else if (handler == ex_handler_uaccess)
+ return EX_HANDLER_UACCESS;
+ else
+ return EX_HANDLER_OTHER;
}

int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code,