Re: AMD Geode NOPL emulation for kernel 2.6.36-rc2
From: Matteo Croce
Date: Fri Aug 27 2010 - 18:19:31 EST
On Sat, Aug 28, 2010 at 12:16 AM, Matteo Croce <matteo@xxxxxxxxxxx> wrote:
> On Fri, Aug 27, 2010 at 11:32 PM, Matteo Croce <matteo@xxxxxxxxxxx> wrote:
>> can I ignore the return value when I expect val to be non zero?
>> the doc says: "On error, the variable @x is set to zero."
>>
>> On Fri, Aug 27, 2010 at 10:49 PM, Thomas Backlund <tmb@xxxxxxxxxxxx> wrote:
>>> 27.08.2010 23:15, Matteo Croce skrev:
>>>>
>>>> On Fri, Aug 27, 2010 at 8:48 PM, H. Peter Anvin<hpa@xxxxxxxxx> Âwrote:
>>>>>
>>>>> You're doing user-space references without get_user().
>>>>>
>>>>> Â Â Â Â-hpa
>>>>>
>>>>> --
>>>>> H. Peter Anvin, Intel Open Source Technology Center
>>>>> I work for Intel. ÂI don't speak on their behalf.
>>>>>
>>>>>
>>>>
>>>> Here with get_user.
>>>> I CC Natale which is my beta tester, he have some Alix boards running
>>>> 24/24
>>>> with my patch
>>>>
>>>> --- a/arch/x86/kernel/Makefile Â2010-08-27 19:42:01.795858001 +0200
>>>> +++ b/arch/x86/kernel/Makefile Â2010-08-27 19:42:12.525858001 +0200
>>>> @@ -88,6 +88,8 @@
>>>> Âobj-$(CONFIG_APB_TIMER) Â Â Â Â Â Â Â += apb_timer.o
>>>>
>>>> Âobj-$(CONFIG_K8_NB) Â Â Â Â Â += k8.o
>>>> +obj-$(CONFIG_GEODE_NOPL) Â Â Â += nopl_emu.o
>>>> +obj-$(CONFIG_GEODE_NOPL) Â Â Â += nopl_emu.o
>>>
>>> Same line added twice...
>>>
>>> --
>>> Thomas
>>>
>>
>>
>>
>> --
>> Matteo Croce
>> OpenWrt developer
>> Â _______Â Â Â Â Â Â Â Â Â ÂÂ ________Â Â Â Â __
>> Â|Â Â ÂÂ |.-----.-----.-----.|Â |Â |Â |.----.|Â |_
>> Â|ÂÂ -ÂÂ ||Â _Â |Â -__|Â ÂÂ ||Â |Â |Â ||ÂÂ _||ÂÂ _|
>> Â|_______||ÂÂ __|_____|__|__||________||__|Â |____|
>> Â Â Â Â Â |__| W I R E L E S SÂÂ F R E E D O M
>> ÂKAMIKAZE (bleeding edge) ------------------
>>  * 10 oz Vodka  Â Shake well with ice and strain
>>  * 10 oz Triple sec mixture into 10 shot glasses.
>>  * 10 oz lime juice Salute!
>> Â---------------------------------------------------
>>
>
> Here is with proper checks
>
> --- a/arch/x86/kernel/Makefile Â2010-08-27 19:42:01.795858001 +0200
> +++ b/arch/x86/kernel/Makefile Â2010-08-27 19:42:12.525858001 +0200
> @@ -88,6 +88,8 @@
> Âobj-$(CONFIG_APB_TIMER) Â Â Â Â Â Â Â Â+= apb_timer.o
>
> Âobj-$(CONFIG_K8_NB) Â Â Â Â Â Â+= k8.o
> +obj-$(CONFIG_GEODE_NOPL) Â Â Â += nopl_emu.o
> +obj-$(CONFIG_GEODE_NOPL) Â Â Â += nopl_emu.o
> Âobj-$(CONFIG_DEBUG_RODATA_TEST) Â Â Â Â+= test_rodata.o
> Âobj-$(CONFIG_DEBUG_NX_TEST) Â Â+= test_nx.o
>
> --- a/arch/x86/kernel/cpu/amd.c 2010-08-27 19:42:01.855858001 +0200
> +++ b/arch/x86/kernel/cpu/amd.c 2010-08-27 19:42:12.535858001 +0200
> @@ -137,11 +137,15 @@
> Â Â Â Â Â Â Â Âreturn;
> Â Â Â Â}
>
> +#ifdef CONFIG_GEODE_NOPL
> Â Â Â Âif (c->x86_model == 10) {
> - Â Â Â Â Â Â Â /* AMD Geode LX is model 10 */
> - Â Â Â Â Â Â Â /* placeholder for any needed mods */
> + Â Â Â Â Â Â Â /* Geode only lacks the NOPL instruction to be i686,
> + Â Â Â Â Â Â Â Â Âbut we can promote it to a i686 class cpu
> + Â Â Â Â Â Â Â Â Âand emulate NOPLs in the exception handler*/
> + Â Â Â Â Â Â Â boot_cpu_data.x86 = 6;
> Â Â Â Â Â Â Â Âreturn;
> Â Â Â Â}
> +#endif
> Â}
>
> Âstatic void __cpuinit amd_k7_smp_check(struct cpuinfo_x86 *c)
> --- a/arch/x86/kernel/entry_32.S Â Â Â Â2010-08-27 19:42:01.735858001 +0200
> +++ b/arch/x86/kernel/entry_32.S Â Â Â Â2010-08-27 19:42:12.535858001 +0200
> @@ -978,7 +978,11 @@
> Â Â Â ÂRING0_INT_FRAME
> Â Â Â Âpushl $0
> Â Â Â ÂCFI_ADJUST_CFA_OFFSET 4
> +#ifdef CONFIG_GEODE_NOPL
> + Â Â Â pushl $do_nopl_emu
> +#else
> Â Â Â Âpushl $do_invalid_op
> +#endif
> Â Â Â ÂCFI_ADJUST_CFA_OFFSET 4
> Â Â Â Âjmp error_code
> Â Â Â ÂCFI_ENDPROC
> --- /dev/null  1970-01-01 00:00:00.000000000 +0000
> +++ b/arch/x86/kernel/nopl_emu.c    Â2010-08-28 00:11:52.627085002 +0200
> @@ -0,0 +1,128 @@
> +/*
> + * Âlinux/arch/x86/kernel/nopl_emu.c
> + *
> + * ÂCopyright (C) 2002 ÂWilly Tarreau
> + * ÂCopyright (C) 2010 ÂMatteo Croce
> + */
> +
> +#include <asm/processor.h>
> +#include <asm/traps.h>
> +#include <asm/uaccess.h>
> +
> +/* This code can be used to allow the AMD Geode to hopefully correctly execute
> + * some code which was originally compiled for an i686, by emulating NOPL,
> + * the only missing i686 instruction in the CPU
> + *
> + * Willy Tarreau <willy@xxxxxxxxxx>
> + * Matteo Croce <technoboy85@xxxxxxxxx>
> + */
> +
> +static inline int do_1f(u8 *ip)
> +{
> + Â Â Â u8 val1, val2;
> + Â Â Â int length = 3;
> + Â Â Â if (get_user(val1, ip))
> + Â Â Â Â Â Â Â return 0;
> + Â Â Â switch (val1) {
> + Â Â Â case 0x84:
> + Â Â Â Â Â Â Â get_user(val1, ip + 5);
> + Â Â Â Â Â Â Â if (!val1)
> + Â Â Â Â Â Â Â Â Â Â Â length++;
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â return 0;
> + Â Â Â case 0x80:
> + Â Â Â Â Â Â Â get_user(val1, ip + 4);
> + Â Â Â Â Â Â Â get_user(val2, ip + 3);
> + Â Â Â Â Â Â Â if (!val1 && !val2)
> + Â Â Â Â Â Â Â Â Â Â Â length += 2;
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â return 0;
> + Â Â Â case 0x44:
> + Â Â Â Â Â Â Â get_user(val1, ip + 2);
> + Â Â Â Â Â Â Â if (!val1)
> + Â Â Â Â Â Â Â Â Â Â Â length++;
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â return 0;
> + Â Â Â case 0x40:
> + Â Â Â Â Â Â Â get_user(val1, ip + 1);
> + Â Â Â Â Â Â Â if (!val1)
> + Â Â Â Â Â Â Â Â Â Â Â length++;
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â return 0;
> + Â Â Â case 0x00:
> + Â Â Â Â Â Â Â return length;
> + Â Â Â }
> + Â Â Â return 0;
> +}
> +
> +static inline int do_0f(u8 *ip)
> +{
> + Â Â Â u8 val;
> + Â Â Â if (get_user(val, ip))
> + Â Â Â Â Â Â Â return 0;
> + Â Â Â if (val == 0x1f)
> + Â Â Â Â Â Â Â return do_1f(ip + 1);
> + Â Â Â return 0;
> +}
> +
> +static inline int do_66(u8 *ip)
> +{
> + Â Â Â u8 val;
> + Â Â Â if (get_user(val, ip))
> + Â Â Â Â Â Â Â return 0;
> + Â Â Â if (val == 0x90)
> + Â Â Â Â Â Â Â return 2;
> + Â Â Â if (val == 0x0f) {
> + Â Â Â Â Â Â Â int res = do_0f(ip + 1);
> + Â Â Â Â Â Â Â if (res)
> + Â Â Â Â Â Â Â Â Â Â Â return res + 1;
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â return 0;
> + Â Â Â }
> + Â Â Â return 0;
> +}
> +
> +static inline int do_start(u8 *ip)
> +{
> + Â Â Â u8 val;
> + Â Â Â if (get_user(val, ip))
> + Â Â Â Â Â Â Â return 0;
> + Â Â Â if (val == 0x0f)
> + Â Â Â Â Â Â Â return do_0f(ip + 1);
> + Â Â Â if (val == 0x66)
> + Â Â Â Â Â Â Â return do_66(ip + 1);
> + Â Â Â return 0;
> +}
> +
> +/* [do_nopl_emu] is called by exception 6 after an invalid opcode has been
> + * encountered. It will try to emulate it by doing nothing,
> + * and will send a SIGILL or SIGSEGV to the process if not possible.
> + * the NOPL can have variable length opcodes:
> +
> +bytes number  opcode
> + Â Â Â 2 Â Â Â 66 90
> + Â Â Â 3 Â Â Â 0f 1f 00
> + Â Â Â 4 Â Â Â 0f 1f 40 00
> + Â Â Â 5 Â Â Â 0f 1f 44 00 00
> + Â Â Â 6 Â Â Â 66 0f 1f 44 00 00
> + Â Â Â 7 Â Â Â 0f 1f 80 00 00 00 00
> + Â Â Â 8 Â Â Â 0f 1f 84 00 00 00 00 00
> + Â Â Â 9 Â Â Â 66 0f 1f 84 00 00 00 00 00
> +*/
> +void do_nopl_emu(struct pt_regs *regs, long error_code)
> +{
> + Â Â Â u8 *ip = (u8 *)instruction_pointer(regs);
> + Â Â Â int res = do_start(ip);
> +
> + Â Â Â if (res) {
> + Â Â Â Â Â Â Â int i = 0;
> + Â Â Â Â Â Â Â do {
> + Â Â Â Â Â Â Â Â Â Â Â ip += res;
> + Â Â Â Â Â Â Â Â Â Â Â i++;
> + Â Â Â Â Â Â Â Â Â Â Â res = do_start(ip);
> + Â Â Â Â Â Â Â } while(res);
> + Â Â Â Â Â Â Â printk(KERN_DEBUG "geode_nopl: emulated %d instructions\n", i);
> + Â Â Â Â Â Â Â regs->ip = (typeof(regs->ip))ip;
> + Â Â Â } else
> + Â Â Â Â Â Â Â do_invalid_op(regs, error_code);
> +}
>
>
> --
> Matteo Croce
> OpenWrt developer
> Â _______Â Â Â Â Â Â Â Â Â ÂÂ ________Â Â Â Â __
> Â|Â Â ÂÂ |.-----.-----.-----.|Â |Â |Â |.----.|Â |_
> Â|ÂÂ -ÂÂ ||Â _Â |Â -__|Â ÂÂ ||Â |Â |Â ||ÂÂ _||ÂÂ _|
> Â|_______||ÂÂ __|_____|__|__||________||__|Â |____|
> Â Â Â Â Â |__| W I R E L E S SÂÂ F R E E D O M
> ÂKAMIKAZE (bleeding edge) ------------------
>  * 10 oz Vodka  Â Shake well with ice and strain
>  * 10 oz Triple sec mixture into 10 shot glasses.
>  * 10 oz lime juice Salute!
> Â---------------------------------------------------
>
Sorry still left the duplicated line
--- a/arch/x86/kernel/Makefile 2010-08-27 19:42:01.795858001 +0200
+++ b/arch/x86/kernel/Makefile 2010-08-28 00:16:53.607507000 +0200
@@ -88,6 +88,7 @@
obj-$(CONFIG_APB_TIMER) += apb_timer.o
obj-$(CONFIG_K8_NB) += k8.o
+obj-$(CONFIG_GEODE_NOPL) += nopl_emu.o
obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
--- a/arch/x86/kernel/cpu/amd.c 2010-08-27 19:42:01.855858001 +0200
+++ b/arch/x86/kernel/cpu/amd.c 2010-08-27 19:42:12.535858001 +0200
@@ -137,11 +137,15 @@
return;
}
+#ifdef CONFIG_GEODE_NOPL
if (c->x86_model == 10) {
- /* AMD Geode LX is model 10 */
- /* placeholder for any needed mods */
+ /* Geode only lacks the NOPL instruction to be i686,
+ but we can promote it to a i686 class cpu
+ and emulate NOPLs in the exception handler*/
+ boot_cpu_data.x86 = 6;
return;
}
+#endif
}
static void __cpuinit amd_k7_smp_check(struct cpuinfo_x86 *c)
--- a/arch/x86/kernel/entry_32.S 2010-08-27 19:42:01.735858001 +0200
+++ b/arch/x86/kernel/entry_32.S 2010-08-27 19:42:12.535858001 +0200
@@ -978,7 +978,11 @@
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
+#ifdef CONFIG_GEODE_NOPL
+ pushl $do_nopl_emu
+#else
pushl $do_invalid_op
+#endif
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ b/arch/x86/kernel/nopl_emu.c 2010-08-28 00:11:52.627085002 +0200
@@ -0,0 +1,128 @@
+/*
+ * linux/arch/x86/kernel/nopl_emu.c
+ *
+ * Copyright (C) 2002 Willy Tarreau
+ * Copyright (C) 2010 Matteo Croce
+ */
+
+#include <asm/processor.h>
+#include <asm/traps.h>
+#include <asm/uaccess.h>
+
+/* This code can be used to allow the AMD Geode to hopefully correctly execute
+ * some code which was originally compiled for an i686, by emulating NOPL,
+ * the only missing i686 instruction in the CPU
+ *
+ * Willy Tarreau <willy@xxxxxxxxxx>
+ * Matteo Croce <technoboy85@xxxxxxxxx>
+ */
+
+static inline int do_1f(u8 *ip)
+{
+ u8 val1, val2;
+ int length = 3;
+ if (get_user(val1, ip))
+ return 0;
+ switch (val1) {
+ case 0x84:
+ get_user(val1, ip + 5);
+ if (!val1)
+ length++;
+ else
+ return 0;
+ case 0x80:
+ get_user(val1, ip + 4);
+ get_user(val2, ip + 3);
+ if (!val1 && !val2)
+ length += 2;
+ else
+ return 0;
+ case 0x44:
+ get_user(val1, ip + 2);
+ if (!val1)
+ length++;
+ else
+ return 0;
+ case 0x40:
+ get_user(val1, ip + 1);
+ if (!val1)
+ length++;
+ else
+ return 0;
+ case 0x00:
+ return length;
+ }
+ return 0;
+}
+
+static inline int do_0f(u8 *ip)
+{
+ u8 val;
+ if (get_user(val, ip))
+ return 0;
+ if (val == 0x1f)
+ return do_1f(ip + 1);
+ return 0;
+}
+
+static inline int do_66(u8 *ip)
+{
+ u8 val;
+ if (get_user(val, ip))
+ return 0;
+ if (val == 0x90)
+ return 2;
+ if (val == 0x0f) {
+ int res = do_0f(ip + 1);
+ if (res)
+ return res + 1;
+ else
+ return 0;
+ }
+ return 0;
+}
+
+static inline int do_start(u8 *ip)
+{
+ u8 val;
+ if (get_user(val, ip))
+ return 0;
+ if (val == 0x0f)
+ return do_0f(ip + 1);
+ if (val == 0x66)
+ return do_66(ip + 1);
+ return 0;
+}
+
+/* [do_nopl_emu] is called by exception 6 after an invalid opcode has been
+ * encountered. It will try to emulate it by doing nothing,
+ * and will send a SIGILL or SIGSEGV to the process if not possible.
+ * the NOPL can have variable length opcodes:
+
+bytes number opcode
+ 2 66 90
+ 3 0f 1f 00
+ 4 0f 1f 40 00
+ 5 0f 1f 44 00 00
+ 6 66 0f 1f 44 00 00
+ 7 0f 1f 80 00 00 00 00
+ 8 0f 1f 84 00 00 00 00 00
+ 9 66 0f 1f 84 00 00 00 00 00
+*/
+void do_nopl_emu(struct pt_regs *regs, long error_code)
+{
+ u8 *ip = (u8 *)instruction_pointer(regs);
+ int res = do_start(ip);
+
+ if (res) {
+ int i = 0;
+ do {
+ ip += res;
+ i++;
+ res = do_start(ip);
+ } while(res);
+ printk(KERN_DEBUG "geode_nopl: emulated %d instructions\n", i);
+ regs->ip = (typeof(regs->ip))ip;
+ } else
+ do_invalid_op(regs, error_code);
+}
--
Matteo Croce
OpenWrt developer
 _______         Â ________    __
Â|Â Â ÂÂ |.-----.-----.-----.|Â |Â |Â |.----.|Â |_
Â|ÂÂ -ÂÂ ||Â _Â |Â -__|Â ÂÂ ||Â |Â |Â ||ÂÂ _||ÂÂ _|
Â|_______||ÂÂ __|_____|__|__||________||__|Â |____|
     |__| W I R E L E S S F R E E D O M
ÂKAMIKAZE (bleeding edge) ------------------
 * 10 oz Vodka  Â Shake well with ice and strain
 * 10 oz Triple sec mixture into 10 shot glasses.
 * 10 oz lime juice Salute!
Â---------------------------------------------------
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