From a67f913d6635772af746fc215066e3d510ae25d1 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Fri, 15 Mar 2024 13:12:22 +0000 Subject: [librm] Add support for installing a startup IPI handler Application processors are started via INIT and SIPI interprocessor interrupts: the INIT places the processor into a "wait for SIPI" state, and the SIPI then starts the processor in real mode at a page-aligned address derived from the SIPI vector number. Add support for installing a real-mode SIPI handler that will switch the CPU into protected mode with flat physical addressing, load initial register contents, and then jump to the address of a protected-mode SIPI handler. No stack pointer is set up, to avoid the need to allocate stack space for each available processor. We use 32-bit physical addressing in order to minimise the changes required for a 64-bit build. The existing long mode transition code relies on the existence of the stack, so we cannot easily switch the application processor into long mode. We could use 32-bit virtual addressing, but this runtime environment does not currently exist outside of librm.S itself in a 64-bit build, and using it would complicate the implementation of the protected-mode SIPI handler. Signed-off-by: Michael Brown --- src/arch/x86/include/librm.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'src/arch/x86/include/librm.h') diff --git a/src/arch/x86/include/librm.h b/src/arch/x86/include/librm.h index 40f07543..84b345d3 100644 --- a/src/arch/x86/include/librm.h +++ b/src/arch/x86/include/librm.h @@ -474,6 +474,26 @@ extern struct page_table io_pages; */ #define IO_BASE ( ( void * ) 0x100000000ULL ) +/** Startup IPI real-mode handler */ +extern char __text16_array ( sipi, [] ); +#define sipi __use_text16 ( sipi ) + +/** Length of startup IPI real-mode handler */ +extern char sipi_len[]; + +/** Startup IPI real-mode handler copy of real-mode data segment */ +extern uint16_t __text16 ( sipi_ds ); +#define sipi_ds __use_text16 ( sipi_ds ) + +/** Startup IPI protected-mode handler (physical address) */ +extern uint32_t sipi_handler; + +/** Startup IPI register state */ +extern struct i386_regs sipi_regs; + +extern void setup_sipi ( unsigned int vector, uint32_t handler, + struct i386_regs *regs ); + #endif /* ASSEMBLY */ #endif /* LIBRM_H */ -- cgit v1.2.3-55-g7522