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x86/mpx: remove bounds exception code 

From: Dave Hansen <dave.hansen@linux.intel.com>

MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).

Remove the other user-visible ABI: signal handling.  This code
should basically have been inactive after the prctl()s were
removed, but there may be some small ABI remnants from this code.
Remove it.

Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
This commit is contained in:
Dave Hansen 2020-01-23 10:41:15 -08:00 committed by Dave Hansen
parent 4ba68d0005
commit aa9ccb7b47
1 changed files with 0 additions and 74 deletions
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74
arch/x86/kernel/traps.c
View File

@ -57,8 +57,6 @@
#include <asm/mach_traps.h>
#include <asm/alternative.h>
#include <asm/fpu/xstate.h>
#include <asm/trace/mpx.h>
#include <asm/mpx.h>
#include <asm/vm86.h>
#include <asm/umip.h>
@ -430,8 +428,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
{
const struct mpx_bndcsr *bndcsr;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
if (notify_die(DIE_TRAP, "bounds", regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
@ -441,76 +437,6 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
if (!user_mode(regs))
die("bounds", regs, error_code);
if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
/* The exception is not from Intel MPX */
goto exit_trap;
}
/*
* We need to look at BNDSTATUS to resolve this exception.
* A NULL here might mean that it is in its 'init state',
* which is all zeros which indicates MPX was not
* responsible for the exception.
*/
bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR);
if (!bndcsr)
goto exit_trap;
trace_bounds_exception_mpx(bndcsr);
/*
* The error code field of the BNDSTATUS register communicates status
* information of a bound range exception #BR or operation involving
* bound directory.
*/
switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
case 2: /* Bound directory has invalid entry. */
if (mpx_handle_bd_fault())
goto exit_trap;
break; /* Success, it was handled */
case 1: /* Bound violation. */
{
struct task_struct *tsk = current;
struct mpx_fault_info mpx;
if (mpx_fault_info(&mpx, regs)) {
/*
* We failed to decode the MPX instruction. Act as if
* the exception was not caused by MPX.
*/
goto exit_trap;
}
/*
* Success, we decoded the instruction and retrieved
* an 'mpx' containing the address being accessed
* which caused the exception. This information
* allows and application to possibly handle the
* #BR exception itself.
*/
if (!do_trap_no_signal(tsk, X86_TRAP_BR, "bounds", regs,
error_code))
break;
show_signal(tsk, SIGSEGV, "trap ", "bounds", regs, error_code);
force_sig_bnderr(mpx.addr, mpx.lower, mpx.upper);
break;
}
case 0: /* No exception caused by Intel MPX operations. */
goto exit_trap;
default:
die("bounds", regs, error_code);
}
return;
exit_trap:
/*
* This path out is for all the cases where we could not
* handle the exception in some way (like allocating a
* table or telling userspace about it. We will also end
* up here if the kernel has MPX turned off at compile
* time..
*/
do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
}