Messages in this thread Patch in this message | | | Subject | Re: AMD Geode NOPL emulation for kernel 2.6.36-rc2 | From | "H. Peter Anvin" <> | Date | Fri, 27 Aug 2010 13:54:58 -0700 |
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You actually have to check the get_user return, or use exception brackets....
"Matteo Croce" <matteo@openwrt.org> wrote:
>On Fri, Aug 27, 2010 at 8:48 PM, H. Peter Anvin <hpa@zytor.com> wrote: >> You're doing user-space references without get_user(). >> >> -hpa >> >> -- >> H. Peter Anvin, Intel Open Source Technology Center >> I work for Intel. I 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 2010-08-27 19:42:01.795858001 +0200 >+++ b/arch/x86/kernel/Makefile 2010-08-27 19:42:12.525858001 +0200 >@@ -88,6 +88,8 @@ > obj-$(CONFIG_APB_TIMER) += apb_timer.o > > obj-$(CONFIG_K8_NB) += k8.o >+obj-$(CONFIG_GEODE_NOPL) += nopl_emu.o >+obj-$(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 2010-08-27 22:09:58.005858001 +0200 >@@ -0,0 +1,124 @@ >+/* >+ * 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@meta-x.org> >+ * Matteo Croce <technoboy85@gmail.com> >+ */ >+ >+static inline int do_1f(u8 *ip) >+{ >+ u8 val1, val2; >+ int length = 3; >+ get_user(val1, ip); >+ 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; >+ get_user(val, ip); >+ if (val == 0x1f) >+ return do_1f(ip + 1); >+ return 0; >+} >+ >+static inline int do_66(u8 *ip) >+{ >+ u8 val; >+ get_user(val, ip); >+ 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; >+ get_user(val, ip); >+ 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 > _______ ________ __ > | |.-----.-----.-----.| | | |.----.| |_ > | - || _ | -__| || | | || _|| _| > |_______|| __|_____|__|__||________||__| |____| > |__| W I R E L E S S F R E E D O M > KAMIKAZE (bleeding edge) ------------------ > * 10 oz Vodka Shake well with ice and strain > * 10 oz Triple sec mixture into 10 shot glasses. > * 10 oz lime juice Salute! > --------------------------------------------------- >
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