Messages in this thread Patch in this message | | | Date | Mon, 18 May 2015 22:36:01 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH 03/19] x86, mpx: use new tsk_get_xsave_addr() |
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On Fri, 8 May 2015, Dave Hansen wrote:
> Subject: x86, mpx: use new tsk_get_xsave_addr()
-NOSUCHFUNCTION
And please let the sentence start with an upper case letter.
x86, mpx: Use ...
> #ifdef CONFIG_X86_INTEL_MPX > siginfo_t *mpx_generate_siginfo(struct pt_regs *regs, > - struct xsave_struct *xsave_buf); > -int mpx_handle_bd_fault(struct xsave_struct *xsave_buf); > + struct task_struct *tsk); > +int mpx_handle_bd_fault(struct task_struct *tsk);
So you still keep *tsk and remove it in the next patch. I guess either ordering has its value, so no problem to do it this way.
> static inline int kernel_managing_mpx_tables(struct mm_struct *mm) > { > return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR); > @@ -78,11 +78,11 @@ void mpx_notify_unmap(struct mm_struct * > unsigned long start, unsigned long end); > #else > static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs, > - struct xsave_struct *xsave_buf) > + struct task_struct *tsk)
But that makes no sense. Introduce a new instance just to remove it one patch later. So maybe cleaning up the *tsk thing first might be the better approach, but I let you decide.
> #include <asm/mach_traps.h> > #include <asm/alternative.h> > #include <asm/mpx.h> > +#include <asm/xsave.h> > > #ifdef CONFIG_X86_64 > #include <asm/x86_init.h> > @@ -372,7 +373,6 @@ dotraplinkage void do_double_fault(struc > dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) > { > struct task_struct *tsk = current; > - struct xsave_struct *xsave_buf; > enum ctx_state prev_state; > struct bndcsr *bndcsr; > siginfo_t *info; > @@ -393,12 +393,11 @@ dotraplinkage void do_bounds(struct pt_r > > /* > * 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. > */ > - fpu_save_init(&tsk->thread.fpu); > - xsave_buf = &(tsk->thread.fpu.state->xsave); > - bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR); > + bndcsr = get_xsave_field(XSTATE_BNDCSR);
Hmm, I did not notice when I looked at the patch which introduced get_xsave_field(). But with the removed get_xsave_addr() I really had to look twice.
get_xsave_field() suggest that you get the field content. So wouldn't it be better to name it get_xsave_field_ptr() or such?
> if (!bndcsr) > goto exit_trap; > > @@ -409,11 +408,11 @@ dotraplinkage void do_bounds(struct pt_r > */ > 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 > diff -puN arch/x86/mm/mpx.c~use-new-tsk_get_xsave_addr arch/x86/mm/mpx.c > --- a/arch/x86/mm/mpx.c~use-new-tsk_get_xsave_addr 2015-05-08 11:46:11.388599581 -0700 > +++ b/arch/x86/mm/mpx.c 2015-05-08 11:46:11.393599807 -0700 > @@ -273,7 +273,7 @@ bad_opcode: > * The caller is expected to kfree() the returned siginfo_t. > */ > siginfo_t *mpx_generate_siginfo(struct pt_regs *regs, > - struct xsave_struct *xsave_buf) > + struct task_struct *tsk)
Looking at the implementation makes me wonder about the extra *tsk argument some more ....
> { > struct bndreg *bndregs, *bndreg; > siginfo_t *info = NULL; > @@ -295,8 +295,8 @@ siginfo_t *mpx_generate_siginfo(struct p > err = -EINVAL; > goto err_out; > } > - /* get the bndregs _area_ of the xsave structure */ > - bndregs = get_xsave_addr(xsave_buf, XSTATE_BNDREGS); > + /* get bndregs field from urrent task's xsave area */
urrent?
> + bndregs = get_xsave_field(XSTATE_BNDREGS); > if (!bndregs) { > err = -EINVAL; > goto err_out;
Still no user of *tsk ....
> @@ -358,8 +358,7 @@ static __user void *task_get_bounds_dir( > -int mpx_handle_bd_fault(struct xsave_struct *xsave_buf) > +int mpx_handle_bd_fault(struct task_struct *tsk) > { > /* > * Userspace never asked us to manage the bounds tables, > @@ -535,7 +534,7 @@ int mpx_handle_bd_fault(struct xsave_str > if (!kernel_managing_mpx_tables(current->mm)) > return -EINVAL; > > - if (do_mpx_bt_fault(xsave_buf)) { > + if (do_mpx_bt_fault(tsk)) {
Same problem actually with do_mpx_bt_fault().
Thanks,
tglx
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