linux/arch/x86/include/asm/syscalls.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* syscalls.h - Linux syscall interfaces (arch-specific)
*
* Copyright (c) 2008 Jaswinder Singh Rajput
*/
#ifndef _ASM_X86_SYSCALLS_H
#define _ASM_X86_SYSCALLS_H
#include <linux/compiler.h>
#include <linux/linkage.h>
#include <linux/signal.h>
#include <linux/types.h>
/* Common in X86_32 and X86_64 */
/* kernel/ioport.c */
long ksys_ioperm(unsigned long from, unsigned long num, int turn_on);
syscalls/x86: Use 'struct pt_regs' based syscall calling convention for 64-bit syscalls Let's make use of ARCH_HAS_SYSCALL_WRAPPER=y on pure 64-bit x86-64 systems: Each syscall defines a stub which takes struct pt_regs as its only argument. It decodes just those parameters it needs, e.g: asmlinkage long sys_xyzzy(const struct pt_regs *regs) { return SyS_xyzzy(regs->di, regs->si, regs->dx); } This approach avoids leaking random user-provided register content down the call chain. For example, for sys_recv() which is a 4-parameter syscall, the assembly now is (in slightly reordered fashion): <sys_recv>: callq <__fentry__> /* decode regs->di, ->si, ->dx and ->r10 */ mov 0x70(%rdi),%rdi mov 0x68(%rdi),%rsi mov 0x60(%rdi),%rdx mov 0x38(%rdi),%rcx [ SyS_recv() is automatically inlined by the compiler, as it is not [yet] used anywhere else ] /* clear %r9 and %r8, the 5th and 6th args */ xor %r9d,%r9d xor %r8d,%r8d /* do the actual work */ callq __sys_recvfrom /* cleanup and return */ cltq retq The only valid place in an x86-64 kernel which rightfully calls a syscall function on its own -- vsyscall -- needs to be modified to pass struct pt_regs onwards as well. To keep the syscall table generation working independent of SYSCALL_PTREGS being enabled, the stubs are named the same as the "original" syscall stubs, i.e. sys_*(). This patch is based on an original proof-of-concept | From: Linus Torvalds <torvalds@linux-foundation.org> | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> and was split up and heavily modified by me, in particular to base it on ARCH_HAS_SYSCALL_WRAPPER, to limit it to 64-bit-only for the time being, and to update the vsyscall to the new calling convention. Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180405095307.3730-4-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-05 17:53:02 +08:00
#ifdef CONFIG_X86_32
syscalls/core, syscalls/x86: Clean up compat syscall stub naming convention Tidy the naming convention for compat syscall subs. Hints which describe the purpose of the stub go in front and receive a double underscore to denote that they are generated on-the-fly by the COMPAT_SYSCALL_DEFINEx() macro. For the generic case, this means: t kernel_waitid # common C function (see kernel/exit.c) __do_compat_sys_waitid # inlined helper doing the actual work # (takes original parameters as declared) T __se_compat_sys_waitid # sign-extending C function calling inlined # helper (takes parameters of type long, # casts them to unsigned long and then to # the declared type) T compat_sys_waitid # alias to __se_compat_sys_waitid() # (taking parameters as declared), to # be included in syscall table For x86, the naming is as follows: t kernel_waitid # common C function (see kernel/exit.c) __do_compat_sys_waitid # inlined helper doing the actual work # (takes original parameters as declared) t __se_compat_sys_waitid # sign-extending C function calling inlined # helper (takes parameters of type long, # casts them to unsigned long and then to # the declared type) T __ia32_compat_sys_waitid # IA32_EMULATION 32-bit-ptregs -> C stub, # calls __se_compat_sys_waitid(); to be # included in syscall table T __x32_compat_sys_waitid # x32 64-bit-ptregs -> C stub, calls # __se_compat_sys_waitid(); to be included # in syscall table If only one of IA32_EMULATION and x32 is enabled, __se_compat_sys_waitid() may be inlined into the stub __{ia32,x32}_compat_sys_waitid(). Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180409105145.5364-3-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-09 18:51:43 +08:00
/*
* These definitions are only valid on pure 32-bit systems; x86-64 uses a
* different syscall calling convention
syscalls/x86: Use 'struct pt_regs' based syscall calling convention for 64-bit syscalls Let's make use of ARCH_HAS_SYSCALL_WRAPPER=y on pure 64-bit x86-64 systems: Each syscall defines a stub which takes struct pt_regs as its only argument. It decodes just those parameters it needs, e.g: asmlinkage long sys_xyzzy(const struct pt_regs *regs) { return SyS_xyzzy(regs->di, regs->si, regs->dx); } This approach avoids leaking random user-provided register content down the call chain. For example, for sys_recv() which is a 4-parameter syscall, the assembly now is (in slightly reordered fashion): <sys_recv>: callq <__fentry__> /* decode regs->di, ->si, ->dx and ->r10 */ mov 0x70(%rdi),%rdi mov 0x68(%rdi),%rsi mov 0x60(%rdi),%rdx mov 0x38(%rdi),%rcx [ SyS_recv() is automatically inlined by the compiler, as it is not [yet] used anywhere else ] /* clear %r9 and %r8, the 5th and 6th args */ xor %r9d,%r9d xor %r8d,%r8d /* do the actual work */ callq __sys_recvfrom /* cleanup and return */ cltq retq The only valid place in an x86-64 kernel which rightfully calls a syscall function on its own -- vsyscall -- needs to be modified to pass struct pt_regs onwards as well. To keep the syscall table generation working independent of SYSCALL_PTREGS being enabled, the stubs are named the same as the "original" syscall stubs, i.e. sys_*(). This patch is based on an original proof-of-concept | From: Linus Torvalds <torvalds@linux-foundation.org> | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> and was split up and heavily modified by me, in particular to base it on ARCH_HAS_SYSCALL_WRAPPER, to limit it to 64-bit-only for the time being, and to update the vsyscall to the new calling convention. Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180405095307.3730-4-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-05 17:53:02 +08:00
*/
asmlinkage long sys_ioperm(unsigned long, unsigned long, int);
asmlinkage long sys_iopl(unsigned int);
/* kernel/ldt.c */
asmlinkage long sys_modify_ldt(int, void __user *, unsigned long);
/* kernel/signal.c */
asmlinkage long sys_rt_sigreturn(void);
/* kernel/tls.c */
asmlinkage long sys_set_thread_area(struct user_desc __user *);
asmlinkage long sys_get_thread_area(struct user_desc __user *);
/* X86_32 only */
/* kernel/signal.c */
asmlinkage long sys_sigreturn(void);
/* kernel/vm86_32.c */
struct vm86_struct;
asmlinkage long sys_vm86old(struct vm86_struct __user *);
asmlinkage long sys_vm86(unsigned long, unsigned long);
#endif /* CONFIG_X86_32 */
#endif /* _ASM_X86_SYSCALLS_H */