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H. Peter Anvin
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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: H. Peter Anvin <hpa@linux.intel.com>
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-46
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5 files changed

+84
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lines changed

‎arch/x86/um/Makefile

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,8 @@ subarch-$(CONFIG_MODULES) += ../kernel/module.o
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USER_OBJS := bugs_$(BITS).o ptrace_user.o fault.o
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3939
extra-y += user-offsets.s
40-
$(obj)/user-offsets.s: c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS)
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$(obj)/user-offsets.s: c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) \
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-Iarch/x86/include/generated
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UNPROFILE_OBJS := stub_segv.o
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CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)

‎arch/x86/um/sys_call_table_32.S

Lines changed: 0 additions & 26 deletions
This file was deleted.

‎arch/x86/um/sys_call_table_32.c

Lines changed: 55 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,55 @@
1+
/*
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* System call table for UML/i386, copied from arch/x86/kernel/syscall_*.c
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* with some changes for UML.
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*/
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6+
#include <linux/linkage.h>
7+
#include <linux/sys.h>
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#include <linux/cache.h>
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#include <generated/user_constants.h>
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11+
#define __NO_STUBS
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/*
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* Below you can see, in terms of #define's, the differences between the x86-64
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* and the UML syscall table.
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*/
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18+
/* Not going to be implemented by UML, since we have no hardware. */
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#define stub_iopl sys_ni_syscall
20+
#define sys_ioperm sys_ni_syscall
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#define sys_vm86old sys_ni_syscall
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#define sys_vm86 sys_ni_syscall
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25+
#define old_mmap sys_old_mmap
26+
27+
#define ptregs_fork sys_fork
28+
#define ptregs_execve sys_execve
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#define ptregs_iopl sys_iopl
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#define ptregs_vm86old sys_vm86old
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#define ptregs_clone sys_clone
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#define ptregs_vm86 sys_vm86
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#define ptregs_sigaltstack sys_sigaltstack
34+
#define ptregs_vfork sys_vfork
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36+
#define __SYSCALL_I386(nr, sym, compat) extern asmlinkage void sym(void) ;
37+
#include <asm/syscalls_32.h>
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#undef __SYSCALL_I386
40+
#define __SYSCALL_I386(nr, sym, compat) [ nr ] = sym,
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typedef void (*sys_call_ptr_t)(void);
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extern void sys_ni_syscall(void);
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sys_call_ptr_t sys_call_table[] __cacheline_aligned = {
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/*
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* Smells like a compiler bug -- it doesn't work
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* when the & below is removed.
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*/
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[0 ... __NR_syscall_max] = &sys_ni_syscall,
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#include <asm/syscalls_32.h>
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};
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int syscall_table_size = sizeof(sys_call_table);

‎arch/x86/um/sys_call_table_64.c

Lines changed: 12 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,12 @@
11
/*
2-
* System call table for UML/x86-64, copied from arch/x86_64/kernel/syscall.c
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* System call table for UML/x86-64, copied from arch/x86/kernel/syscall_*.c
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* with some changes for UML.
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*/
55

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#include <linux/linkage.h>
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#include <linux/sys.h>
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#include <linux/cache.h>
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#include <generated/user_constants.h>
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#define __NO_STUBS
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@@ -34,31 +35,23 @@
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#define stub_sigaltstack sys_sigaltstack
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#define stub_rt_sigreturn sys_rt_sigreturn
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37-
#define __SYSCALL(nr, sym) extern asmlinkage void sym(void) ;
38-
#undef _ASM_X86_UNISTD_64_H
39-
#include "../../x86/include/asm/unistd_64.h"
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#define __SYSCALL_64(nr, sym, compat) extern asmlinkage void sym(void) ;
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#include <asm/syscalls_64.h>
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#undef __SYSCALL
42-
#define __SYSCALL(nr, sym) [ nr ] = sym,
43-
#undef _ASM_X86_UNISTD_64_H
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#undef __SYSCALL_64
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#define __SYSCALL_64(nr, sym, compat) [ nr ] = sym,
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4544
typedef void (*sys_call_ptr_t)(void);
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4746
extern void sys_ni_syscall(void);
4847

49-
/*
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* We used to have a trick here which made sure that holes in the
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* x86_64 table were filled in with sys_ni_syscall, but a comment in
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* unistd_64.h says that holes aren't allowed, so the trick was
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* removed.
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* The trick looked like this
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* [0 ... UM_NR_syscall_max] = &sys_ni_syscall
56-
* before including unistd_64.h - the later initializations overwrote
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* the sys_ni_syscall filler.
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*/
59-
6048
sys_call_ptr_t sys_call_table[] __cacheline_aligned = {
61-
#include <asm/unistd_64.h>
49+
/*
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* Smells like a compiler bug -- it doesn't work
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* when the & below is removed.
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*/
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[0 ... __NR_syscall_max] = &sys_ni_syscall,
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#include <asm/syscalls_64.h>
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};
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6457
int syscall_table_size = sizeof(sys_call_table);

‎arch/x86/um/user-offsets.c

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,18 @@
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#include <asm/ptrace.h>
99
#include <asm/types.h>
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11+
#ifdef __i386__
12+
#define __SYSCALL_I386(nr, sym, compat) [nr] = 1,
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static char syscalls[] = {
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#include <asm/syscalls_32.h>
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};
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#else
17+
#define __SYSCALL_64(nr, sym, compat) [nr] = 1,
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static char syscalls[] = {
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#include <asm/syscalls_64.h>
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};
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#endif
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1123
#define DEFINE(sym, val) \
1224
asm volatile("\n->" #sym " %0 " #val : : "i" (val))
1325

@@ -77,4 +89,7 @@ void foo(void)
7789
DEFINE(UM_PROT_READ, PROT_READ);
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DEFINE(UM_PROT_WRITE, PROT_WRITE);
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DEFINE(UM_PROT_EXEC, PROT_EXEC);
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93+
DEFINE(__NR_syscall_max, sizeof(syscalls) - 1);
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DEFINE(NR_syscalls, sizeof(syscalls));
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}

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