On Mon, Feb 23, 2015 at 4:12 PM, Denys Vlasenko <[email protected]> wrote: > Constants such as SS+8 or SS+8-RIP are mysterious. > In most cases, SS+8 is just meant to be SIZEOF_PTREGS, > SS+8-RIP is RIP's offset in iret frame. > > This patch changes some of these constants to be less mysterious. > > No code changes (verified with objdump).
Applied. > > Signed-off-by: Denys Vlasenko <[email protected]> > CC: Linus Torvalds <[email protected]> > CC: Oleg Nesterov <[email protected]> > CC: Borislav Petkov <[email protected]> > CC: "H. Peter Anvin" <[email protected]> > CC: Andy Lutomirski <[email protected]> > CC: Frederic Weisbecker <[email protected]> > CC: X86 ML <[email protected]> > CC: Alexei Starovoitov <[email protected]> > CC: Will Drewry <[email protected]> > CC: Kees Cook <[email protected]> > CC: [email protected] > --- > arch/x86/include/asm/calling.h | 2 ++ > arch/x86/kernel/entry_64.S | 28 ++++++++++++++++------------ > 2 files changed, 18 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/include/asm/calling.h b/arch/x86/include/asm/calling.h > index 4a7ceb9..3374235 100644 > --- a/arch/x86/include/asm/calling.h > +++ b/arch/x86/include/asm/calling.h > @@ -88,6 +88,8 @@ For 32-bit we have the following conventions - kernel is > built with > #define RSP 19*8 > #define SS 20*8 > > +#define SIZEOF_PTREGS 21*8 > + > .macro ALLOC_PT_GPREGS_ON_STACK addskip=0 > subq $15*8+\addskip, %rsp > CFI_ADJUST_CFA_OFFSET 15*8+\addskip > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index c628a1b..2fa9e59 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -164,12 +164,12 @@ ENDPROC(native_usergs_sysret64) > * initial frame state for interrupts (and exceptions without error code) > */ > .macro INTR_FRAME start=1 offset=0 > - EMPTY_FRAME \start, SS+8+\offset-RIP > - /*CFI_REL_OFFSET ss, SS+\offset-RIP*/ > - CFI_REL_OFFSET rsp, RSP+\offset-RIP > - /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/ > - /*CFI_REL_OFFSET cs, CS+\offset-RIP*/ > - CFI_REL_OFFSET rip, RIP+\offset-RIP > + EMPTY_FRAME \start, 5*8+\offset > + /*CFI_REL_OFFSET ss, 4*8+\offset*/ > + CFI_REL_OFFSET rsp, 3*8+\offset > + /*CFI_REL_OFFSET rflags, 2*8+\offset*/ > + /*CFI_REL_OFFSET cs, 1*8+\offset*/ > + CFI_REL_OFFSET rip, 0*8+\offset > .endm > > /* > @@ -177,7 +177,7 @@ ENDPROC(native_usergs_sysret64) > * with vector already pushed) > */ > .macro XCPT_FRAME start=1 offset=0 > - INTR_FRAME \start, RIP+\offset-ORIG_RAX > + INTR_FRAME \start, 1*8+\offset > .endm > > /* > @@ -644,10 +644,14 @@ END(interrupt) > cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp > CFI_DEF_CFA_REGISTER rsi > pushq %rsi > + /* > + * For debugger: > + * "CFA (Current Frame Address) is the value on stack + offset" > + */ > CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \ > - 0x77 /* DW_OP_breg7 */, 0, \ > + 0x77 /* DW_OP_breg7 (rsp) */, 0, \ > 0x06 /* DW_OP_deref */, \ > - 0x08 /* DW_OP_const1u */, SS+8-RBP, \ > + 0x08 /* DW_OP_const1u */, SIZEOF_PTREGS-RBP, \ > 0x22 /* DW_OP_plus */ > /* We entered an interrupt context - irqs are off: */ > TRACE_IRQS_OFF > @@ -673,7 +677,7 @@ ret_from_intr: > > /* Restore saved previous stack */ > popq %rsi > - CFI_DEF_CFA rsi,SS+8-RBP /* reg/off reset after def_cfa_expr */ > + CFI_DEF_CFA rsi,SIZEOF_PTREGS-RBP /* reg/off reset after def_cfa_expr > */ > /* return code expects complete pt_regs - adjust rsp accordingly: */ > leaq -RBP(%rsi),%rsp > CFI_DEF_CFA_REGISTER rsp > @@ -1539,7 +1543,7 @@ first_nmi: > .rept 5 > pushq_cfi 11*8(%rsp) > .endr > - CFI_DEF_CFA_OFFSET SS+8-RIP > + CFI_DEF_CFA_OFFSET 5*8 > > /* Everything up to here is safe from nested NMIs */ > > @@ -1567,7 +1571,7 @@ repeat_nmi: > pushq_cfi -6*8(%rsp) > .endr > subq $(5*8), %rsp > - CFI_DEF_CFA_OFFSET SS+8-RIP > + CFI_DEF_CFA_OFFSET 5*8 > end_repeat_nmi: > > /* > -- > 1.8.1.4 > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
