[PATCH v3 2/6] x86/mce: Provide method to find out the type of exception handle

Tony Luck
2020-10-06T21:09:30Z

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>
---
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 d8c2198d543b..1f0cbc52937c 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 0b072dc231ad..c6494e6579c1 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 1d6cb07f4f86..de43525df69b 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,
--
2.21.1