[kvm-unit-tests PATCH 1/1] x86: use pointer for end of exception table

From: Bill Wendling <morbo@google.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com, alexandru.elisei@arm.com
Cc: jmattson@google.com, Bill Wendling <morbo@google.com>
Subject: [kvm-unit-tests PATCH 1/1] x86: use pointer for end of exception table
Date: Sun, 13 Oct 2019 00:18:24 -0700	[thread overview]
Message-ID: <20191013071824.222946-1-morbo@google.com> (raw)
In-Reply-To: <20191012074454.208377-2-morbo@google.com>

Two global objects can't have the same address in C. Clang uses this
fact to omit the check on the first iteration of the loop in
check_exception_table.

Signed-off-by: Bill Wendling <morbo@google.com>
---
 lib/x86/desc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index 451f504..cfc449f 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -41,7 +41,7 @@ struct ex_record {
     unsigned long handler;
 };
 
-extern struct ex_record exception_table_start, exception_table_end;
+extern struct ex_record exception_table_start, *exception_table_end;
 
 static const char* exception_mnemonic(int vector)
 {
@@ -113,7 +113,7 @@ static void check_exception_table(struct ex_regs *regs)
 		(((regs->rflags >> 16) & 1) << 8);
     asm("mov %0, %%gs:4" : : "r"(ex_val));
 
-    for (ex = &exception_table_start; ex != &exception_table_end; ++ex) {
+    for (ex = &exception_table_start; ex != (void*)&exception_table_end; ++ex) {
         if (ex->rip == regs->rip) {
             regs->rip = ex->handler;
             return;
-- 
2.23.0.700.g56cf767bdb-goog

