[PATCH] vm86 syscall wrappers

[PATCH] vm86 syscall wrappers

[idunham]

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There are two vm86 syscalls that Linux supports:
vm86old and vm86plus.
(Musl uses SYS_vm86 to refer to vm86plus)

This patch adds wrappers for both, using the names that modern glibc uses.

Practically speaking, this should help with compiling dosemu, several
graphics-card utilities, and a few other system tools.

Isaac Dunham

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diff --git a/arch/i386/bits/vm86.h b/arch/i386/bits/vm86.h
new file mode 100644
index 0000000..808fa42
--- /dev/null
+++ b/arch/i386/bits/vm86.h
@@ -0,0 +1,154 @@
+#ifndef _BITS_VM86_H
+#define _BITS_VM86_H
+
+#define X86_EFLAGS_CF	0x00000001 
+#define X86_EFLAGS_PF	0x00000004 
+#define X86_EFLAGS_AF	0x00000010 
+#define X86_EFLAGS_ZF	0x00000040 
+#define X86_EFLAGS_SF	0x00000080 
+#define X86_EFLAGS_TF	0x00000100 
+#define X86_EFLAGS_IF	0x00000200 
+#define X86_EFLAGS_DF	0x00000400 
+#define X86_EFLAGS_OF	0x00000800 
+#define X86_EFLAGS_IOPL	0x00003000 
+#define X86_EFLAGS_NT	0x00004000 
+#define X86_EFLAGS_RF	0x00010000 
+#define X86_EFLAGS_VM	0x00020000 
+#define X86_EFLAGS_AC	0x00040000 
+#define X86_EFLAGS_VIF	0x00080000 
+#define X86_EFLAGS_VIP	0x00100000 
+#define X86_EFLAGS_ID	0x00200000 
+
+#define X86_CR0_PE	0x00000001 
+#define X86_CR0_MP	0x00000002 
+#define X86_CR0_EM	0x00000004 
+#define X86_CR0_TS	0x00000008 
+#define X86_CR0_ET	0x00000010 
+#define X86_CR0_NE	0x00000020 
+#define X86_CR0_WP	0x00010000 
+#define X86_CR0_AM	0x00040000 
+#define X86_CR0_NW	0x20000000 
+#define X86_CR0_CD	0x40000000 
+#define X86_CR0_PG	0x80000000 
+
+#define X86_CR3_PWT	0x00000008 
+#define X86_CR3_PCD	0x00000010 
+
+#define X86_CR4_VME	0x00000001 
+#define X86_CR4_PVI	0x00000002 
+#define X86_CR4_TSD	0x00000004 
+#define X86_CR4_DE	0x00000008 
+#define X86_CR4_PSE	0x00000010 
+#define X86_CR4_PAE	0x00000020 
+#define X86_CR4_MCE	0x00000040 
+#define X86_CR4_PGE	0x00000080 
+#define X86_CR4_PCE	0x00000100 
+#define X86_CR4_OSFXSR	0x00000200 
+#define X86_CR4_OSXMMEXCPT 0x00000400 
+#define X86_CR4_VMXE	0x00002000 
+#define X86_CR4_OSXSAVE 0x00040000 
+
+#define X86_CR8_TPR	0x0000000F 
+
+#define CX86_PCR0	0x20
+#define CX86_GCR	0xb8
+#define CX86_CCR0	0xc0
+#define CX86_CCR1	0xc1
+#define CX86_CCR2	0xc2
+#define CX86_CCR3	0xc3
+#define CX86_CCR4	0xe8
+#define CX86_CCR5	0xe9
+#define CX86_CCR6	0xea
+#define CX86_CCR7	0xeb
+#define CX86_PCR1	0xf0
+#define CX86_DIR0	0xfe
+#define CX86_DIR1	0xff
+#define CX86_ARR_BASE	0xc4
+#define CX86_RCR_BASE	0xdc
+
+#define BIOSSEG		0x0f000
+
+#define CPU_086		0
+#define CPU_186		1
+#define CPU_286		2
+#define CPU_386		3
+#define CPU_486		4
+#define CPU_586		5
+
+#define VM86_TYPE(retval)	((retval) & 0xff)
+#define VM86_ARG(retval)	((retval) >> 8)
+
+#define VM86_SIGNAL	0
+#define VM86_UNKNOWN	1
+#define VM86_INTx	2
+#define VM86_STI	3
+#define VM86_PICRETURN	4
+#define VM86_TRAP	6
+
+#define VM86_PLUS_INSTALL_CHECK	0
+#define VM86_ENTER		1
+#define VM86_ENTER_NO_BYPASS	2
+#define	VM86_REQUEST_IRQ	3
+#define VM86_FREE_IRQ		4
+#define VM86_GET_IRQ_BITS	5
+#define VM86_GET_AND_RESET_IRQ	6
+
+struct vm86_regs {
+	long ebx;
+	long ecx;
+	long edx;
+	long esi;
+	long edi;
+	long ebp;
+	long eax;
+	long __null_ds;
+	long __null_es;
+	long __null_fs;
+	long __null_gs;
+	long orig_eax;
+	long eip;
+	unsigned short cs, __csh;
+	long eflags;
+	long esp;
+	unsigned short ss, __ssh;
+	unsigned short es, __esh;
+	unsigned short ds, __dsh;
+	unsigned short fs, __fsh;
+	unsigned short gs, __gsh;
+};
+
+struct revectored_struct {
+	unsigned long __map[8];
+};
+
+struct vm86_struct {
+	struct vm86_regs regs;
+	unsigned long flags;
+	unsigned long screen_bitmap;
+	unsigned long cpu_type;
+	struct revectored_struct int_revectored;
+	struct revectored_struct int21_revectored;
+};
+
+#define VM86_SCREEN_BITMAP	0x0001
+
+struct vm86plus_info_struct {
+	unsigned long force_return_for_pic:1;
+	unsigned long vm86dbg_active:1;
+	unsigned long vm86dbg_TFpendig:1;
+	unsigned long unused:28;
+	unsigned long is_vm86pus:1;
+	unsigned char vm86dbg_intxxtab[32];
+};
+struct vm86plus_struct {
+	struct vm86_regs regs;
+	unsigned long flags;
+	unsigned long screen_bitmap;
+	unsigned long cpu_type;
+	struct revectored_struct int_revectored;
+	struct revectored_struct int21_revectored;
+	struct vm86plus_info_struct vm86plus;
+};
+
+
+#endif
diff --git a/include/sys/vm86.h b/include/sys/vm86.h
new file mode 100644
index 0000000..a8eb3d7
--- /dev/null
+++ b/include/sys/vm86.h
@@ -0,0 +1,9 @@
+#ifndef _SYS_VM86_H
+#define _SYS_VM86_H
+
+#include bits/vm86.h
+
+int vm86old(struct vm86_struct *info);
+int vm86(unsigned long fn, struct vm86plus_struct *v86);
+
+#endif
diff --git a/src/linux/vm86.c b/src/linux/vm86.c
new file mode 100644
index 0000000..5ade96a
--- /dev/null
+++ b/src/linux/vm86.c
@@ -0,0 +1,26 @@
+/*
+ * vm86plus/vm86old support.
+ * vm86old is the original vm86, as provided by libc5, klibc, & glibc <2.3.3
+ * vm86(plus) is the new syscall; glibc 2.3.4 + calls this vm86, and renames
+ * vm86 as originally implemented to vm86old.
+ * The question is thus which to call vm86.
+ */
+#include "syscall.h"
+
+#ifdef SYS_vm86old
+struct vm86_struct;
+
+int vm86old(struct vm86_struct *info)
+{
+	return syscall(SYS_vm86old, info);
+}
+#endif
+
+#ifdef SYS_vm86
+struct vm86plus_struct;
+
+int vm86(unsigned long fn, struct vm86plus_struct *v86)
+{
+	return syscall(SYS_vm86, fn, v86);
+}
+#endif

Re: [PATCH] vm86 syscall wrappers

[Luca Barbato]

On 08/17/2012 02:32 AM, idunham@lavabit.com wrote:
> +	unsigned long is_vm86pus:1;

typo?

Re: [PATCH] vm86 syscall wrappers

[idunham]

> On 08/17/2012 02:32 AM, idunham@lavabit.com wrote:
>> +	unsigned long is_vm86pus:1;
>
> typo?

Nope, that's what asm/vm86.h calls it.
(note: rather than #include files from the kernel headers, I followed the
standing practice for musl and copied the relevant definitions, without
any comments. This means you don't need to install kernel headers for the
target before you can cross-compile)