@@ -22,7 +22,8 @@ static void gp_handler(struct ex_regs *regs)
#define GP_ASM(stmt, in, clobber) \
- asm ("mov" W " $1f, %[expected_rip]\n\t" \
+ asm volatile ( \
+ "mov" W " $1f, %[expected_rip]\n\t" \
"movl $2f-1f, %[skip_count]\n\t" \
"1: " stmt "\n\t" \
"2: " \
@@ -159,7 +160,8 @@ static int do_ring3(void (*fn)(const char *), const char *arg)
: [ret] "=&a" (ret)
: [user_ds] "i" (USER_DS),
[user_cs] "i" (USER_CS),
- [user_stack_top]"m"(user_stack[sizeof user_stack]),
+ [user_stack_top]"m"(user_stack[sizeof(user_stack) -
+ sizeof(long)]),
[fn]"r"(fn),
[arg]"D"(arg),
[kernel_ds]"i"(KERNEL_DS),
When compiling umip.c with -O2 instead of -O1, there are currently two problems. First, the compiler complains: x86/umip.c: In function ‘do_ring3’: x86/umip.c:162:37: error: array subscript 4096 is above array bounds of ‘unsigned char[4096]’ [-Werror=array-bounds] [user_stack_top]"m"(user_stack[sizeof user_stack]), ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ This can be fixed by initializing the stack to point to one of the last bytes of the array instead. The second problem is that some tests are failing - and this is due to the fact that the GP_ASM macro uses inline asm without the "volatile" keyword - so that the compiler reorders this code in certain cases where it should not. Fix it by adding "volatile" here. Message-Id: <20200122160944.29750-1-thuth@redhat.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com> --- x86/umip.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)