linux-kernel - [PATCH 5/6] x86: Make exception handler functions visible

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Date:   Thu, 21 Dec 2017 16:18:20 -0800
From:   Andi Kleen <andi@...stfloor.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 5/6] x86: Make exception handler functions visible

From: Andi Kleen <ak@...ux.intel.com>

Make the C exception handler functions that are directly called through
exception tables visible. LTO needs to know they are accessed from assembler.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/mm/extable.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 9fe656c42aa5..8bd4b864e681 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -21,7 +21,7 @@ ex_fixup_handler(const struct exception_table_entry *x)
 	return (ex_handler_t)((unsigned long)&x->handler + x->handler);
 }
 
-bool ex_handler_default(const struct exception_table_entry *fixup,
+__visible bool ex_handler_default(const struct exception_table_entry *fixup,
 		       struct pt_regs *regs, int trapnr)
 {
 	regs->ip = ex_fixup_addr(fixup);
@@ -29,7 +29,7 @@ bool ex_handler_default(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_default);
 
-bool ex_handler_fault(const struct exception_table_entry *fixup,
+__visible bool ex_handler_fault(const struct exception_table_entry *fixup,
 		     struct pt_regs *regs, int trapnr)
 {
 	regs->ip = ex_fixup_addr(fixup);
@@ -42,7 +42,7 @@ EXPORT_SYMBOL_GPL(ex_handler_fault);
  * Handler for UD0 exception following a failed test against the
  * result of a refcount inc/dec/add/sub.
  */
-bool ex_handler_refcount(const struct exception_table_entry *fixup,
+__visible bool ex_handler_refcount(const struct exception_table_entry *fixup,
 			 struct pt_regs *regs, int trapnr)
 {
 	/* First unconditionally saturate the refcount. */
@@ -95,6 +95,7 @@ EXPORT_SYMBOL(ex_handler_refcount);
  * of vulnerability by restoring from the initial state (essentially, zeroing
  * out all the FPU registers) if we can't restore from the task's FPU state.
  */
+__visible
 bool ex_handler_fprestore(const struct exception_table_entry *fixup,
 			  struct pt_regs *regs, int trapnr)
 {
@@ -108,7 +109,7 @@ bool ex_handler_fprestore(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL_GPL(ex_handler_fprestore);
 
-bool ex_handler_ext(const struct exception_table_entry *fixup,
+__visible bool ex_handler_ext(const struct exception_table_entry *fixup,
 		   struct pt_regs *regs, int trapnr)
 {
 	/* Special hack for uaccess_err */
@@ -118,7 +119,7 @@ bool ex_handler_ext(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_ext);
 
-bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
+__visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
 			     struct pt_regs *regs, int trapnr)
 {
 	if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pF)\n",
@@ -133,7 +134,7 @@ bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
 
-bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
+__visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
 			     struct pt_regs *regs, int trapnr)
 {
 	if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pF)\n",
@@ -147,7 +148,7 @@ bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
 
-bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
+__visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
 			 struct pt_regs *regs, int trapnr)
 {
 	if (static_cpu_has(X86_BUG_NULL_SEG))
@@ -157,7 +158,7 @@ bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_clear_fs);
 
-bool ex_has_fault_handler(unsigned long ip)
+__visible bool ex_has_fault_handler(unsigned long ip)
 {
 	const struct exception_table_entry *e;
 	ex_handler_t handler;
-- 
2.15.0