diff options
| -rw-r--r-- | src/cpu/x86/64bit/Makefile.inc | 1 | ||||
| -rw-r--r-- | src/cpu/x86/64bit/mode_switch2.S | 48 | ||||
| -rw-r--r-- | src/cpu/x86/64bit/prot2long.inc | 27 |
3 files changed, 76 insertions, 0 deletions
diff --git a/src/cpu/x86/64bit/Makefile.inc b/src/cpu/x86/64bit/Makefile.inc index e1cf743f6c..24a5a966fb 100644 --- a/src/cpu/x86/64bit/Makefile.inc +++ b/src/cpu/x86/64bit/Makefile.inc @@ -1,6 +1,7 @@ ## SPDX-License-Identifier: GPL-2.0-only all_x86-y += mode_switch.S +all_x86-y += mode_switch2.S # Add --defsym=_start=0 to suppress a linker warning. $(objcbfs)/pt: $(dir)/pt.S $(obj)/config.h diff --git a/src/cpu/x86/64bit/mode_switch2.S b/src/cpu/x86/64bit/mode_switch2.S new file mode 100644 index 0000000000..65e9d94a98 --- /dev/null +++ b/src/cpu/x86/64bit/mode_switch2.S @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Calls a x86_64 function from x86_32 context. + * Must not be directly invoked from C code! + */ + +.text +.code32 + .section ".text.long_mode_call_3arg", "ax", @progbits + .global long_mode_call_3arg +long_mode_call_3arg: + + /* Function to call is passed in EAX. */ + + /* Backup registers */ + pushal + + /* Backup stack pointer */ + mov %esp, %ebp + + /* Enter long mode, preserves ebx */ + #include <cpu/x86/64bit/entry64.inc> + + /* Align stack */ + movabs $0xfffffffffffffff0, %rax + andq %rax, %rsp + + movl 28(%rbp), %ebx /* Function to call */ + movl 36(%rbp), %edi /* 1st arg */ + movl 40(%rbp), %esi /* 2nd arg */ + movl 44(%rbp), %edx /* 3rd arg */ + + call *%rbx + + /* Store return value on stack. popal will fetch it. */ + mov %eax, 28(%rbp) + shr $32, %rax + movl %eax, 24(%rbp) + + #include <cpu/x86/64bit/exit32.inc> + + /* Restore stack pointer */ + mov %ebp, %esp + + /* Restore registers */ + popal + + ret diff --git a/src/cpu/x86/64bit/prot2long.inc b/src/cpu/x86/64bit/prot2long.inc new file mode 100644 index 0000000000..96c44a86f5 --- /dev/null +++ b/src/cpu/x86/64bit/prot2long.inc @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +.text +.code32 +/* + * Macro to wrap a x86_64 function to be called from x86_32 code. + * This assumes that 0-3 32bit arguments are passed to the + * calling function. + * + * In order to preserve ESP without setting up a stack frame + * pass the function to call in EAX. The macro prepends "__prot2lm_" + * to the wrapped function name. + */ +.macro prot2lm_wrapper func2call:req + .global __prot2lm_\func2call +__prot2lm_\func2call : + /* Get function to call */ + mov $\func2call, %eax + + /* + * Jump to function instead of call. + * It will return directly to caller. + */ + jmp long_mode_call_3arg + + /* Not reachable */ +.endm |