Messages in this thread Patch in this message | | | From | Brian Gerst <> | Subject | [PATCH 1/4] x86-32: Rework cache flush denied handler | Date | Sun, 21 Mar 2010 09:00:43 -0400 |
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The cache flush denied error is an erratum on some AMD 486 clones. If an invd instruction is executed in userspace, the processor calls exception 19 (13 hex) instead of #GP (13 decimal). On cpus where XMM is not supported, redirect exception 19 to do_general_protection(). Also, remove die_if_kernel(), since this was the last user.
Signed-off-by: Brian Gerst <brgerst@gmail.com> --- arch/x86/Kconfig.cpu | 4 ++++ arch/x86/kernel/entry_32.S | 19 +++++++++++++++++++ arch/x86/kernel/traps.c | 31 +++---------------------------- 3 files changed, 26 insertions(+), 28 deletions(-)
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index f20ddf8..1012e8a 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -338,6 +338,10 @@ config X86_F00F_BUG def_bool y depends on M586MMX || M586TSC || M586 || M486 || M386 +config X86_INVD_BUG + def_bool y + depends on M486 || M386 + config X86_WP_WORKS_OK def_bool y depends on !M386 diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 44a8e0d..1e958b8 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -53,6 +53,7 @@ #include <asm/processor-flags.h> #include <asm/ftrace.h> #include <asm/irq_vectors.h> +#include <asm/cpufeature.h> /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ #include <linux/elf-em.h> @@ -905,7 +906,25 @@ ENTRY(simd_coprocessor_error) RING0_INT_FRAME pushl $0 CFI_ADJUST_CFA_OFFSET 4 +#ifdef CONFIG_X86_INVD_BUG + /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */ +661: pushl $do_general_protection +662: +.section .altinstructions,"a" + .balign 4 + .long 661b + .long 663f + .byte X86_FEATURE_XMM + .byte 662b-661b + .byte 664f-663f +.previous +.section .altinstr_replacement,"ax" +663: pushl $do_simd_coprocessor_error +664: +.previous +#else pushl $do_simd_coprocessor_error +#endif CFI_ADJUST_CFA_OFFSET 4 jmp error_code CFI_ENDPROC diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 3339917..bb4a7b3 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -108,15 +108,6 @@ static inline void preempt_conditional_cli(struct pt_regs *regs) dec_preempt_count(); } -#ifdef CONFIG_X86_32 -static inline void -die_if_kernel(const char *str, struct pt_regs *regs, long err) -{ - if (!user_mode_vm(regs)) - die(str, regs, err); -} -#endif - static void __kprobes do_trap(int trapnr, int signr, char *str, struct pt_regs *regs, long error_code, siginfo_t *info) @@ -726,30 +717,14 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code) conditional_sti(regs); #ifdef CONFIG_X86_32 - if (cpu_has_xmm) { - /* Handle SIMD FPU exceptions on PIII+ processors. */ - ignore_fpu_irq = 1; - simd_math_error((void __user *)regs->ip); - return; - } - /* - * Handle strange cache flush from user space exception - * in all other cases. This is undocumented behaviour. - */ - if (regs->flags & X86_VM_MASK) { - handle_vm86_fault((struct kernel_vm86_regs *)regs, error_code); - return; - } - current->thread.trap_no = 19; - current->thread.error_code = error_code; - die_if_kernel("cache flush denied", regs, error_code); - force_sig(SIGSEGV, current); + ignore_fpu_irq = 1; #else if (!user_mode(regs) && kernel_math_error(regs, "kernel simd math error", 19)) return; - simd_math_error((void __user *)regs->ip); #endif + + simd_math_error((void __user *)regs->ip); } dotraplinkage void -- 1.6.6.1
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