Fix vfork #293
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Fix vfork #293
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This boots and stays up over weekend. So I suppose we can just merge it? saluki> uptime |
There was an error in the fork() routine when system calls are in use: the child context is saved on the child's user stack, which is incorrect, the context must be saved on the kernel stack instead. The result is a full system crash if (when) the child executes on a different CPU which does not have the same MMU mappings active.
We need to record the parent's integer register context upon exception entry to a separate non-volatile area. Why? Because xcp.regs can move due to a context switch within the fork() system call, be it either via interrupt or a synchronization point. Fix this by adding a "sregs" area where the saved user context is placed. The critical section within fork() is also unnecessary.
This commit fixes the regression from apache#13561 In order to determine whether a context switch has occurred, we can use g_running_task to store the current regs. This allows us to compare the current register state with the previously stored state to identify if a context switch has taken place. Signed-off-by: hujun5 <[email protected]>
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This is all in upstream so it is totally fine to merge it. Good to hear it's stable now, I was not 100% convinced myself. |
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Summary
Cherry picks from upstream
Impact
Testing