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cpu/x86/64bit/mode_switch: Simplify assembly code

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Drop the first argument specifying the number of arguments pushed
to the stack. Instead always push the 3 arguments to stack and use
the first one as function pointer to call while in protected mode.

While on it add more comments and simplify register restore code.

Tested:
- On qemu can call x86_32 function and pass argument and return
  value.
- Booted Lenovo X220 in x86_64 mode using x86_32 MRC.

Change-Id: I30809453a1800ba3c0df60acd7eca778841c520f
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79752
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Patrick Rudolph
2023-12-28 07:44:26 +01:00
committed by Lean Sheng Tan
parent b14b96d29a
commit b4283a4fbb
2 changed files with 45 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
src/arch/x86/include/mode_switch.h
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@@ -3,10 +3,18 @@
#include <stdint.h>
#if ENV_X86_64
int protected_mode_call_narg(uint32_t arg_count,
uint32_t func_ptr,
/*
* Assembly code that drops into protected mode and calls the function
* specified as first argument, which must have been compiled for x86_32.
* After the function returns it enters long mode again.
* The function pointer destination must be below 4GiB in physical memory.
*
* The called function has 0-3 arguments and returns an int.
*/
int protected_mode_call_3arg(uint32_t func_ptr,
uint32_t opt_arg1,
uint32_t opt_arg2);
uint32_t opt_arg2,
uint32_t opt_arg3);
/*
* Drops into protected mode and calls the function, which must have been compiled for x86_32.
@@ -17,7 +25,7 @@ int protected_mode_call_narg(uint32_t arg_count,
*/
static inline int protected_mode_call(void *func)
{
return protected_mode_call_narg(0, (uintptr_t)func, 0, 0);
return protected_mode_call_3arg((uintptr_t)func, 0, 0, 0);
}
/*
@@ -30,7 +38,7 @@ static inline int protected_mode_call(void *func)
*/
static inline int protected_mode_call_1arg(void *func, uint32_t arg1)
{
return protected_mode_call_narg(1, (uintptr_t)func, arg1, 0);
return protected_mode_call_3arg((uintptr_t)func, arg1, 0, 0);
}
/*
@@ -43,7 +51,7 @@ static inline int protected_mode_call_1arg(void *func, uint32_t arg1)
*/
static inline int protected_mode_call_2arg(void *func, uint32_t arg1, uint32_t arg2)
{
return protected_mode_call_narg(2, (uintptr_t)func, arg1, arg2);
return protected_mode_call_3arg((uintptr_t)func, arg1, arg2, 0);
}
#else
static inline int protected_mode_call(void *func)