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alistair23-linux
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x86-32: Rework cache flush denied handler 

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>
LKML-Reference: <1269176446-2489-2-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
hifive-unleashed-5.1
Brian Gerst 2010-03-21 09:00:43 -04:00 committed by H. Peter Anvin
parent be1066bbcd
commit 40d2e76315
3 changed files with 26 additions and 28 deletions
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4
arch/x86/Kconfig.cpu
View File

@ -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

19
arch/x86/kernel/entry_32.S
View File

@ -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

31
arch/x86/kernel/traps.c
View File

@ -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)
@ -729,30 +720,14 @@ 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);
}
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