linux-kernel - [PATCH 1/2] x86/traps: call cond_local_irq_disable before returning from exc_general_protection and math

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Date:   Thu,  8 Apr 2021 13:28:33 -0400
From:   Thomas Tai <thomas.tai@...cle.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org
Cc:     sean.j.christopherson@...el.com, luto@...capital.net,
        jarkko@...nel.org, bp@...e.de, jethro@...tanix.com,
        alexandre.chartre@...cle.com, linux-kernel@...r.kernel.org,
        thomas.tai@...cle.com
Subject: [PATCH 1/2] x86/traps: call cond_local_irq_disable before returning from exc_general_protection and math_error

This fixes commit 334872a09198 ("x86/traps: Attempt to fixup exceptions
in vDSO before signaling") which added return statements without calling
cond_local_irq_disable(). According to commit ca4c6a9858c2
("x86/traps: Make interrupt enable/disable symmetric in C code"),
cond_local_irq_disable() is needed because the ASM return code no
longer disables interrupts. Follow the existing code as an example to
use "goto exit" instead of "return" statement.

Signed-off-by: Thomas Tai <thomas.tai@...cle.com>
---
 arch/x86/kernel/traps.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index ac1874a..651e3e5 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -556,7 +556,7 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 		tsk->thread.trap_nr = X86_TRAP_GP;
 
 		if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0))
-			return;
+			goto exit;
 
 		show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
 		force_sig(SIGSEGV);
@@ -1057,7 +1057,7 @@ static void math_error(struct pt_regs *regs, int trapnr)
 		goto exit;
 
 	if (fixup_vdso_exception(regs, trapnr, 0, 0))
-		return;
+		goto exit;
 
 	force_sig_fault(SIGFPE, si_code,
 			(void __user *)uprobe_get_trap_addr(regs));
-- 
1.8.3.1