x86: dovetail: Fix inband IRQ state corruption on out-of-band compat …

…syscall

The following kernel splat was found when running the Xenomai 3
testsuite in compat on dovetail enabled kernels:

[  513.620975] IRQ pipeline: some code running in oob context 'Xenomai'
                             called an in-band only routine
[  513.620998] CPU: 0 PID: 510 Comm: smokey Not tainted 6.10.0+ torvalds#76
[  513.621003] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[  513.621005] IRQ stage: Xenomai
[  513.621007] Call Trace:
[  513.621011]  <TASK>
[  513.621015]  dump_stack_lvl+0x6f/0xd0
[  513.621202]  __inband_irq_enable+0xb/0x60
[  513.621249]  do_int80_emulation+0x68/0x160
[  513.621265]  asm_int80_emulation+0x1a/0x20
[  513.621285] RIP: 0023:0xf7f692ba
[  513.621288] Code: Unable to access opcode bytes at 0xf7f69290.
[  513.621303] RSP: 002b:00000000ffeedf40 EFLAGS: 00000282 ORIG_RAX: 0000000000000127
[  513.621307] RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000ffeedfa0
[  513.621309] RDX: 0000000000088000 RSI: 0000000000000000 RDI: 00000000f7f7aff4
[  513.621311] RBP: 00000000ffeedf88 R08: 0000000000000000 R09: 0000000000000000
[  513.621313] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[  513.621315] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[  513.621319]  </TASK>

When entering the low level entry code from the out-of-band stage
the in-band IRQ state was changed. That is now avoided by calling
syscall_enter_from_user_enable_irqs() as all other entry points do.

Signed-off-by: Florian Bezdeka <[email protected]>

arch/x86/entry/common.c

@@ -259,7 +259,7 @@ __visible noinstr void do_int80_emulation(struct pt_regs *regs)
 
 	nr = syscall_32_enter(regs);
 
-	local_irq_enable_full();
+	syscall_enter_from_user_enable_irqs();
 	nr = syscall_enter_from_user_mode_work(regs, nr);
 
 	if (dovetailing()) {