Commit 45db1c61 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, um: Use the same style generated syscall tables as native 



Now when the native kernel uses a single style of generated system
call table, follow suite for UML and implement the same style, all in
C.  This requires __NR_syscall_max and NR_syscalls to be generated; on
native this is done in asm-headers.h but that file is common to all
UML architectures; therefore put it in user-headers.h instead which
already have accommodations for architecture-specific values.

Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 392f4b7d

arch/x86/um/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -37,7 +37,8 @@ subarch-$(CONFIG_MODULES) += ../kernel/module.o 
USER_OBJS := bugs_$(BITS).o ptrace_user.o fault.o



extra-y += user-offsets.s

$(obj)/user-offsets.s: c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS)

$(obj)/user-offsets.s: c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) \

	-Iarch/x86/include/generated



UNPROFILE_OBJS := stub_segv.o

CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)

arch/x86/um/sys_call_table_32.S→arch/x86/um/sys_call_table_32.c

+55 −0
Original line number Diff line number Diff line 
/*

 * System call table for UML/i386, copied from arch/x86/kernel/syscall_*.c

 * with some changes for UML.

 */



#include <linux/linkage.h>

/* Steal i386 syscall table for our purposes, but with some slight changes.*/

#include <linux/sys.h>

#include <linux/cache.h>

#include <generated/user_constants.h>



#define __NO_STUBS



/*

 * Below you can see, in terms of #define's, the differences between the x86-64

 * and the UML syscall table.

 */



#define sys_iopl sys_ni_syscall

/* Not going to be implemented by UML, since we have no hardware. */

#define stub_iopl sys_ni_syscall

#define sys_ioperm sys_ni_syscall



#define sys_vm86old sys_ni_syscall
@@ -18,9 +33,23 @@ 
#define ptregs_sigaltstack sys_sigaltstack

#define ptregs_vfork sys_vfork



.section .rodata,"a"

#define __SYSCALL_I386(nr, sym, compat) extern asmlinkage void sym(void) ;

#include <asm/syscalls_32.h>



#undef __SYSCALL_I386

#define __SYSCALL_I386(nr, sym, compat) [ nr ] = sym,



typedef void (*sys_call_ptr_t)(void);



extern void sys_ni_syscall(void);



#include "../kernel/syscall_table_32.S"

sys_call_ptr_t sys_call_table[] __cacheline_aligned = {

	/*

	 * Smells like a compiler bug -- it doesn't work

	 * when the & below is removed.

	 */

	[0 ... __NR_syscall_max] = &sys_ni_syscall,

#include <asm/syscalls_32.h>

};



ENTRY(syscall_table_size)

.long .-sys_call_table
 
int syscall_table_size = sizeof(sys_call_table);

arch/x86/um/sys_call_table_64.c

+12 −19
Original line number Diff line number Diff line 
/*

 * System call table for UML/x86-64, copied from arch/x86_64/kernel/syscall.c

 * System call table for UML/x86-64, copied from arch/x86/kernel/syscall_*.c

 * with some changes for UML.

 */



#include <linux/linkage.h>

#include <linux/sys.h>

#include <linux/cache.h>

#include <generated/user_constants.h>



#define __NO_STUBS
@@ -34,31 +35,23 @@ 
#define stub_sigaltstack sys_sigaltstack

#define stub_rt_sigreturn sys_rt_sigreturn



#define __SYSCALL(nr, sym) extern asmlinkage void sym(void) ;

#undef _ASM_X86_UNISTD_64_H

#include "../../x86/include/asm/unistd_64.h"

#define __SYSCALL_64(nr, sym, compat) extern asmlinkage void sym(void) ;

#include <asm/syscalls_64.h>



#undef __SYSCALL

#define __SYSCALL(nr, sym) [ nr ] = sym,

#undef _ASM_X86_UNISTD_64_H

#undef __SYSCALL_64

#define __SYSCALL_64(nr, sym, compat) [ nr ] = sym,



typedef void (*sys_call_ptr_t)(void);



extern void sys_ni_syscall(void);



sys_call_ptr_t sys_call_table[] __cacheline_aligned = {

	/*

 * We used to have a trick here which made sure that holes in the

 * x86_64 table were filled in with sys_ni_syscall, but a comment in

 * unistd_64.h says that holes aren't allowed, so the trick was

 * removed.

 * The trick looked like this

 *	[0 ... UM_NR_syscall_max] = &sys_ni_syscall

 * before including unistd_64.h - the later initializations overwrote

 * the sys_ni_syscall filler.

	 * Smells like a compiler bug -- it doesn't work

	 * when the & below is removed.

	 */



sys_call_ptr_t sys_call_table[] __cacheline_aligned = {

#include <asm/unistd_64.h>

	[0 ... __NR_syscall_max] = &sys_ni_syscall,

#include <asm/syscalls_64.h>

};



int syscall_table_size = sizeof(sys_call_table);

arch/x86/um/user-offsets.c

+15 −0
Original line number Diff line number Diff line
@@ -8,6 +8,18 @@ 
#include <asm/ptrace.h>

#include <asm/types.h>



#ifdef __i386__

#define __SYSCALL_I386(nr, sym, compat) [nr] = 1,

static char syscalls[] = {

#include <asm/syscalls_32.h>

};

#else

#define __SYSCALL_64(nr, sym, compat) [nr] = 1,

static char syscalls[] = {

#include <asm/syscalls_64.h>

};

#endif



#define DEFINE(sym, val) \

	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
@@ -77,4 +89,7 @@ void foo(void) 
	DEFINE(UM_PROT_READ, PROT_READ);

	DEFINE(UM_PROT_WRITE, PROT_WRITE);

	DEFINE(UM_PROT_EXEC, PROT_EXEC);



	DEFINE(__NR_syscall_max, sizeof(syscalls) - 1);

	DEFINE(NR_syscalls, sizeof(syscalls));

}

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