Commit 909489bf authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-asm-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 asm updates from Ingo Molnar:

 - Micro-optimize and standardize the do_syscall_64() calling convention

 - Make syscall entry flags clearing more conservative

 - Clean up syscall table handling

 - Clean up & standardize assembly macros, in preparation of FRED

 - Misc cleanups and fixes

* tag 'x86-asm-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm: Make <asm/asm.h> valid on cross-builds as well
  x86/regs: Syscall_get_nr() returns -1 for a non-system call
  x86/entry: Split PUSH_AND_CLEAR_REGS into two submacros
  x86/syscall: Maximize MSR_SYSCALL_MASK
  x86/syscall: Unconditionally prototype {ia32,x32}_sys_call_table[]
  x86/entry: Reverse arguments to do_syscall_64()
  x86/entry: Unify definitions from <asm/calling.h> and <asm/ptrace-abi.h>
  x86/asm: Use _ASM_BYTES() in <asm/nops.h>
  x86/asm: Add _ASM_BYTES() macro for a .byte ... opcode sequence
  x86/asm: Have the __ASM_FORM macros handle commas in arguments
parents e5a0fc4e 41f45fb0

arch/x86/entry/calling.h

+9 −36
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <asm/percpu.h>

#include <asm/asm-offsets.h>

#include <asm/processor-flags.h>

#include <asm/ptrace-abi.h>



/*
@@ -62,42 +63,7 @@ For 32-bit we have the following conventions - kernel is built with 
 * 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 PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0

.macro PUSH_REGS rdx=%rdx rax=%rax save_ret=0

	.if \save_ret

	pushq	%rsi		/* pt_regs->si */

	movq	8(%rsp), %rsi	/* temporarily store the return address in %rsi */
@@ -124,7 +90,9 @@ For 32-bit we have the following conventions - kernel is built with 
	.if \save_ret

	pushq	%rsi		/* return address on top of stack */

	.endif

.endm



.macro CLEAR_REGS

	/*

	 * Sanitize registers of values that a speculation attack might

	 * otherwise want to exploit. The lower registers are likely clobbered
@@ -146,6 +114,11 @@ For 32-bit we have the following conventions - kernel is built with 


.endm



.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0

	PUSH_REGS rdx=\rdx, rax=\rax, save_ret=\save_ret

	CLEAR_REGS

.endm



.macro POP_REGS pop_rdi=1 skip_r11rcx=0

	popq %r15

	popq %r14

arch/x86/entry/common.c

+1 −1
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 
#include <asm/irq_stack.h>



#ifdef CONFIG_X86_64

__visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)

__visible noinstr void do_syscall_64(struct pt_regs *regs, unsigned long nr)

{

	add_random_kstack_offset();

	nr = syscall_enter_from_user_mode(regs, nr);

arch/x86/entry/entry_64.S

+2 −2
Original line number Diff line number Diff line
@@ -107,8 +107,8 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL) 
	PUSH_AND_CLEAR_REGS rax=$-ENOSYS



	/* IRQs are off. */

	movq	%rax, %rdi

	movq	%rsp, %rsi

	movq	%rsp, %rdi

	movq	%rax, %rsi

	call	do_syscall_64		/* returns with IRQs disabled */



	/*

arch/x86/include/asm/asm.h

+16 −11
Original line number Diff line number Diff line
@@ -3,17 +3,18 @@ 
#define _ASM_X86_ASM_H



#ifdef __ASSEMBLY__

# define __ASM_FORM(x)	x

# define __ASM_FORM_RAW(x)     x

# define __ASM_FORM_COMMA(x) x,

# define __ASM_FORM(x, ...)		x,## __VA_ARGS__

# define __ASM_FORM_RAW(x, ...)		x,## __VA_ARGS__

# define __ASM_FORM_COMMA(x, ...)	x,## __VA_ARGS__,

#else

#include <linux/stringify.h>



# define __ASM_FORM(x)	" " __stringify(x) " "

# define __ASM_FORM_RAW(x)     __stringify(x)

# define __ASM_FORM_COMMA(x) " " __stringify(x) ","

# define __ASM_FORM(x, ...)		" " __stringify(x,##__VA_ARGS__) " "

# define __ASM_FORM_RAW(x, ...)		    __stringify(x,##__VA_ARGS__)

# define __ASM_FORM_COMMA(x, ...)	" " __stringify(x,##__VA_ARGS__) ","

#endif



#define _ASM_BYTES(x, ...)	__ASM_FORM(.byte x,##__VA_ARGS__ ;)



#ifndef __x86_64__

/* 32 bit */

# define __ASM_SEL(a,b)		__ASM_FORM(a)
@@ -119,6 +120,8 @@ 
# define CC_OUT(c) [_cc_ ## c] "=qm"

#endif



#ifdef __KERNEL__



/* Exception table entry */

#ifdef __ASSEMBLY__

# define _ASM_EXTABLE_HANDLE(from, to, handler)			\
@@ -185,4 +188,6 @@ register unsigned long current_stack_pointer asm(_ASM_SP); 
#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)

#endif /* __ASSEMBLY__ */



#endif /* __KERNEL__ */



#endif /* _ASM_X86_ASM_H */

arch/x86/include/asm/nops.h

+10 −14
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#ifndef _ASM_X86_NOPS_H

#define _ASM_X86_NOPS_H



#include <asm/asm.h>



/*

 * Define nops for use with alternative() and for tracing.

 */
@@ -57,20 +59,14 @@ 


#endif /* CONFIG_64BIT */



#ifdef __ASSEMBLY__

#define _ASM_MK_NOP(x) .byte x

#else

#define _ASM_MK_NOP(x) ".byte " __stringify(x) "\n"

#endif



#define ASM_NOP1 _ASM_MK_NOP(BYTES_NOP1)

#define ASM_NOP2 _ASM_MK_NOP(BYTES_NOP2)

#define ASM_NOP3 _ASM_MK_NOP(BYTES_NOP3)

#define ASM_NOP4 _ASM_MK_NOP(BYTES_NOP4)

#define ASM_NOP5 _ASM_MK_NOP(BYTES_NOP5)

#define ASM_NOP6 _ASM_MK_NOP(BYTES_NOP6)

#define ASM_NOP7 _ASM_MK_NOP(BYTES_NOP7)

#define ASM_NOP8 _ASM_MK_NOP(BYTES_NOP8)

#define ASM_NOP1 _ASM_BYTES(BYTES_NOP1)

#define ASM_NOP2 _ASM_BYTES(BYTES_NOP2)

#define ASM_NOP3 _ASM_BYTES(BYTES_NOP3)

#define ASM_NOP4 _ASM_BYTES(BYTES_NOP4)

#define ASM_NOP5 _ASM_BYTES(BYTES_NOP5)

#define ASM_NOP6 _ASM_BYTES(BYTES_NOP6)

#define ASM_NOP7 _ASM_BYTES(BYTES_NOP7)

#define ASM_NOP8 _ASM_BYTES(BYTES_NOP8)



#define ASM_NOP_MAX 8