From 21c7e3a41f1590b18c2c3f883e2b63e36cc409aa Mon Sep 17 00:00:00 2001 From: Jan Sommer Date: Wed, 22 Jul 2020 14:41:51 +0200 Subject: i386: Fix possible race condition on first context restore Make sure that the esp is restored before the eflags register. When the init task is initially restored, system interrupts are activated when the eflags register is loaded. If the esp register still points to an address in the interrupt stack area (from early system initlization) the ISR might overwrite its own stack. Closes #4031 --- cpukit/score/cpu/i386/cpu_asm.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'cpukit/score/cpu/i386') diff --git a/cpukit/score/cpu/i386/cpu_asm.S b/cpukit/score/cpu/i386/cpu_asm.S index 6031f6914e..23360959f5 100644 --- a/cpukit/score/cpu/i386/cpu_asm.S +++ b/cpukit/score/cpu/i386/cpu_asm.S @@ -83,9 +83,9 @@ SYM (_CPU_Context_switch): .L_restore: movl I386_CONTEXT_CONTROL_ISR_DISPATCH_DISABLE(eax),ecx movl ecx,PER_CPU_ISR_DISPATCH_DISABLE(edx) + movl REG_ESP(eax),esp /* restore stack pointer */ pushl REG_EFLAGS(eax) /* push eflags */ popf /* restore eflags */ - movl REG_ESP(eax),esp /* restore stack pointer */ movl REG_EBP(eax),ebp /* restore base pointer */ movl REG_EBX(eax),ebx /* restore ebx */ movl REG_ESI(eax),esi /* restore source register */ -- cgit v1.2.3