UefiCpuPkg/CpuDxe: Add stackless assembly AP entry points
The AP startup code simply jumps into this code with the CpuDxe driver without setting up a stack for the processor. Therefore, this code must setup the stack before calling into C code. This is the basic flow: * AP enters CpuDxe driver code (AsmApEntryPoint) without stack - AP grabs a lock - AP sets up stack - AP calls CpuMp.c:ApEntryPointInC - If ApEntryPointInC returns, the lock is freed, and another AP may run - The AP C code may call AsmApDoneWithCommonStack to indicate that the AP is no longer using the stack, and another may therefore proceed to use the stack and then call ApEntryPointInC Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Jeff Fan <jeff.fan@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16347 6f19259b-4bc3-4df7-8a09-765794883524
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@@ -24,5 +24,32 @@ InitializeMpSupport (
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VOID
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);
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/**
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The AP entry point that the Startup-IPI target code will jump to.
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The processor jumps to this code in flat mode, but the processor's
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stack is not initialized.
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**/
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VOID
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EFIAPI
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AsmApEntryPoint (
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VOID
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);
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/**
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Releases the lock preventing other APs from using the shared AP
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stack.
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Once the AP has transitioned to using a new stack, it can call this
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function to allow another AP to proceed with using the shared stack.
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**/
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VOID
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EFIAPI
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AsmApDoneWithCommonStack (
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VOID
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);
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#endif // _CPU_MP_H_
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