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author | Dave Hansen <dave.hansen@linux.intel.com> | 2015-06-07 18:37:01 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-06-09 10:24:30 (GMT) |
commit | a84eeaa96b36a03188e1423349669c108d3a4bd7 (patch) | |
tree | 13f38f8a3859b26458b21cce4cf5ee22851313fb /arch/x86/kernel/traps.c | |
parent | 04cd027bcba1ead7bfe39e7f1c6f4d993c4c3323 (diff) | |
download | linux-a84eeaa96b36a03188e1423349669c108d3a4bd7.tar.xz |
x86/mpx: Use the new get_xsave_field_ptr()API
The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly
accessible via normal instructions. They essentially act as
if they were floating point registers and are saved/restored
along with those registers.
There are two main paths in the MPX code where we care about
the contents of these registers:
1. #BR (bounds) faults
2. the prctl() code where we are setting MPX up
Both of those paths _might_ be called without the FPU having
been used. That means that 'tsk->thread.fpu.state' might
never be allocated.
Also, fpu_save_init() is not preempt-safe. It was a bug to
call it without disabling preemption. The new
get_xsave_addr() calls unlazy_fpu() instead and properly
disables preemption.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183701.BC0D37CF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r-- | arch/x86/kernel/traps.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index a2510f2..42f1531 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -59,6 +59,7 @@ #include <asm/fixmap.h> #include <asm/mach_traps.h> #include <asm/alternative.h> +#include <asm/fpu/xstate.h> #include <asm/mpx.h> #ifdef CONFIG_X86_64 @@ -371,9 +372,8 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) { struct task_struct *tsk = current; - struct xregs_state *xsave_buf; enum ctx_state prev_state; - struct bndcsr *bndcsr; + const struct bndcsr *bndcsr; siginfo_t *info; prev_state = exception_enter(); @@ -392,12 +392,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) /* * We need to look at BNDSTATUS to resolve this exception. - * It is not directly accessible, though, so we need to - * do an xsave and then pull it out of the xsave buffer. + * 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. */ - copy_fpregs_to_fpstate(&tsk->thread.fpu); - xsave_buf = &(tsk->thread.fpu.state.xsave); - bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR); + bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR); if (!bndcsr) goto exit_trap; @@ -408,11 +407,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) */ switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) { case 2: /* Bound directory has invalid entry. */ - if (mpx_handle_bd_fault(xsave_buf)) + if (mpx_handle_bd_fault(tsk)) goto exit_trap; break; /* Success, it was handled */ case 1: /* Bound violation. */ - info = mpx_generate_siginfo(regs, xsave_buf); + info = mpx_generate_siginfo(regs, tsk); if (IS_ERR(info)) { /* * We failed to decode the MPX instruction. Act as if |