x86/asm/entry: Move arch/x86/include/asm/calling.h to arch/x86/entry/

asm/calling.h is private to the entry code, make this more apparent
by moving it to the new arch/x86/entry/ directory.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 243 insertions, 0 deletions

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
new file mode 100644
index 000000000000..f4e6308c4200
--- /dev/null
+++ b/arch/x86/entry/calling.h
@@ -0,0 +1,243 @@
+/*
+
+ x86 function call convention, 64-bit:
+ -------------------------------------
+  arguments           |  callee-saved      | extra caller-saved | return
+ [callee-clobbered]   |                    | [callee-clobbered] |
+ ---------------------------------------------------------------------------
+ rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11             | rax, rdx [**]
+
+ ( rsp is obviously invariant across normal function calls. (gcc can 'merge'
+   functions when it sees tail-call optimization possibilities) rflags is
+   clobbered. Leftover arguments are passed over the stack frame.)
+
+ [*]  In the frame-pointers case rbp is fixed to the stack frame.
+
+ [**] for struct return values wider than 64 bits the return convention is a
+      bit more complex: up to 128 bits width we return small structures
+      straight in rax, rdx. For structures larger than that (3 words or
+      larger) the caller puts a pointer to an on-stack return struct
+      [allocated in the caller's stack frame] into the first argument - i.e.
+      into rdi. All other arguments shift up by one in this case.
+      Fortunately this case is rare in the kernel.
+
+For 32-bit we have the following conventions - kernel is built with
+-mregparm=3 and -freg-struct-return:
+
+ x86 function calling convention, 32-bit:
+ ----------------------------------------
+  arguments         | callee-saved        | extra caller-saved | return
+ [callee-clobbered] |                     | [callee-clobbered] |
+ -------------------------------------------------------------------------
+ eax edx ecx        | ebx edi esi ebp [*] | <none>             | eax, edx [**]
+
+ ( here too esp is obviously invariant across normal function calls. eflags
+   is clobbered. Leftover arguments are passed over the stack frame. )
+
+ [*]  In the frame-pointers case ebp is fixed to the stack frame.
+
+ [**] We build with -freg-struct-return, which on 32-bit means similar
+      semantics as on 64-bit: edx can be used for a second return value
+      (i.e. covering integer and structure sizes up to 64 bits) - after that
+      it gets more complex and more expensive: 3-word or larger struct returns
+      get done in the caller's frame and the pointer to the return struct goes
+      into regparm0, i.e. eax - the other arguments shift up and the
+      function's register parameters degenerate to regparm=2 in essence.
+
+*/
+
+#ifdef CONFIG_X86_64
+
+/*
+ * 64-bit system call stack frame layout defines and helpers,
+ * for assembly code:
+ */
+
+/* The layout forms the "struct pt_regs" on the stack: */
+/*
+ * C ABI says these regs are callee-preserved. They aren't saved on kernel entry
+ * unless syscall needs a complete, fully filled "struct pt_regs".
+ */
+#define R15		0*8
+#define R14		1*8
+#define R13		2*8
+#define R12		3*8
+#define RBP		4*8
+#define RBX		5*8
+/* These regs are callee-clobbered. Always saved on kernel entry. */
+#define R11		6*8
+#define R10		7*8
+#define R9		8*8
+#define R8		9*8
+#define RAX		10*8
+#define RCX		11*8
+#define RDX		12*8
+#define RSI		13*8
+#define RDI		14*8
+/*
+ * On syscall entry, this is syscall#. On CPU exception, this is error code.
+ * On hw interrupt, it's IRQ number:
+ */
+#define ORIG_RAX	15*8
+/* Return frame for iretq */
+#define RIP		16*8
+#define CS		17*8
+#define EFLAGS		18*8
+#define RSP		19*8
+#define SS		20*8
+
+#define SIZEOF_PTREGS	21*8
+
+	.macro ALLOC_PT_GPREGS_ON_STACK addskip=0
+	addq	$-(15*8+\addskip), %rsp
+	.endm
+
+	.macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1
+	.if \r11
+	movq %r11, 6*8+\offset(%rsp)
+	.endif
+	.if \r8910
+	movq %r10, 7*8+\offset(%rsp)
+	movq %r9,  8*8+\offset(%rsp)
+	movq %r8,  9*8+\offset(%rsp)
+	.endif
+	.if \rax
+	movq %rax, 10*8+\offset(%rsp)
+	.endif
+	.if \rcx
+	movq %rcx, 11*8+\offset(%rsp)
+	.endif
+	movq %rdx, 12*8+\offset(%rsp)
+	movq %rsi, 13*8+\offset(%rsp)
+	movq %rdi, 14*8+\offset(%rsp)
+	.endm
+	.macro SAVE_C_REGS offset=0
+	SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1
+	.endm
+	.macro SAVE_C_REGS_EXCEPT_RAX_RCX offset=0
+	SAVE_C_REGS_HELPER \offset, 0, 0, 1, 1
+	.endm
+	.macro SAVE_C_REGS_EXCEPT_R891011
+	SAVE_C_REGS_HELPER 0, 1, 1, 0, 0
+	.endm
+	.macro SAVE_C_REGS_EXCEPT_RCX_R891011
+	SAVE_C_REGS_HELPER 0, 1, 0, 0, 0
+	.endm
+	.macro SAVE_C_REGS_EXCEPT_RAX_RCX_R11
+	SAVE_C_REGS_HELPER 0, 0, 0, 1, 0
+	.endm
+
+	.macro SAVE_EXTRA_REGS offset=0
+	movq %r15, 0*8+\offset(%rsp)
+	movq %r14, 1*8+\offset(%rsp)
+	movq %r13, 2*8+\offset(%rsp)
+	movq %r12, 3*8+\offset(%rsp)
+	movq %rbp, 4*8+\offset(%rsp)
+	movq %rbx, 5*8+\offset(%rsp)
+	.endm
+	.macro SAVE_EXTRA_REGS_RBP offset=0
+	movq %rbp, 4*8+\offset(%rsp)
+	.endm
+
+	.macro RESTORE_EXTRA_REGS offset=0
+	movq 0*8+\offset(%rsp), %r15
+	movq 1*8+\offset(%rsp), %r14
+	movq 2*8+\offset(%rsp), %r13
+	movq 3*8+\offset(%rsp), %r12
+	movq 4*8+\offset(%rsp), %rbp
+	movq 5*8+\offset(%rsp), %rbx
+	.endm
+
+	.macro ZERO_EXTRA_REGS
+	xorl	%r15d, %r15d
+	xorl	%r14d, %r14d
+	xorl	%r13d, %r13d
+	xorl	%r12d, %r12d
+	xorl	%ebp, %ebp
+	xorl	%ebx, %ebx
+	.endm
+
+	.macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1
+	.if \rstor_r11
+	movq 6*8(%rsp), %r11
+	.endif
+	.if \rstor_r8910
+	movq 7*8(%rsp), %r10
+	movq 8*8(%rsp), %r9
+	movq 9*8(%rsp), %r8
+	.endif
+	.if \rstor_rax
+	movq 10*8(%rsp), %rax
+	.endif
+	.if \rstor_rcx
+	movq 11*8(%rsp), %rcx
+	.endif
+	.if \rstor_rdx
+	movq 12*8(%rsp), %rdx
+	.endif
+	movq 13*8(%rsp), %rsi
+	movq 14*8(%rsp), %rdi
+	.endm
+	.macro RESTORE_C_REGS
+	RESTORE_C_REGS_HELPER 1,1,1,1,1
+	.endm
+	.macro RESTORE_C_REGS_EXCEPT_RAX
+	RESTORE_C_REGS_HELPER 0,1,1,1,1
+	.endm
+	.macro RESTORE_C_REGS_EXCEPT_RCX
+	RESTORE_C_REGS_HELPER 1,0,1,1,1
+	.endm
+	.macro RESTORE_C_REGS_EXCEPT_R11
+	RESTORE_C_REGS_HELPER 1,1,0,1,1
+	.endm
+	.macro RESTORE_C_REGS_EXCEPT_RCX_R11
+	RESTORE_C_REGS_HELPER 1,0,0,1,1
+	.endm
+	.macro RESTORE_RSI_RDI
+	RESTORE_C_REGS_HELPER 0,0,0,0,0
+	.endm
+	.macro RESTORE_RSI_RDI_RDX
+	RESTORE_C_REGS_HELPER 0,0,0,0,1
+	.endm
+
+	.macro REMOVE_PT_GPREGS_FROM_STACK addskip=0
+	subq $-(15*8+\addskip), %rsp
+	.endm
+
+	.macro icebp
+	.byte 0xf1
+	.endm
+
+#else /* CONFIG_X86_64 */
+
+/*
+ * For 32bit only simplified versions of SAVE_ALL/RESTORE_ALL. These
+ * are different from the entry_32.S versions in not changing the segment
+ * registers. So only suitable for in kernel use, not when transitioning
+ * from or to user space. The resulting stack frame is not a standard
+ * pt_regs frame. The main use case is calling C code from assembler
+ * when all the registers need to be preserved.
+ */
+
+	.macro SAVE_ALL
+	pushl %eax
+	pushl %ebp
+	pushl %edi
+	pushl %esi
+	pushl %edx
+	pushl %ecx
+	pushl %ebx
+	.endm
+
+	.macro RESTORE_ALL
+	popl %ebx
+	popl %ecx
+	popl %edx
+	popl %esi
+	popl %edi
+	popl %ebp
+	popl %eax
+	.endm
+
+#endif /* CONFIG_X86_64 */
+