From 911d2bb5ccaab102abbab2bb58438c75bc342ca9 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Thu, 26 Feb 2015 14:40:36 -0800 Subject: [PATCH] x86/asm/entry/64: Use more readable constants 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 the iret frame. This patch changes some of these constants to be less mysterious. No code changes (verified with objdump). Signed-off-by: Denys Vlasenko Signed-off-by: Andy Lutomirski Cc: Alexei Starovoitov Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Thomas Gleixner Cc: Will Drewry Link: http://lkml.kernel.org/r/1d20491384773bd606e23a382fac23ddb49b5178.1424989793.git.luto@amacapital.net Signed-off-by: Ingo Molnar --- 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 4a7ceb9789a5..337423590b08 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 466947770648..858e94e86f5e 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 /* @@ -645,10 +645,14 @@ 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 @@ -674,7 +678,7 @@ 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 @@ -1549,7 +1553,7 @@ 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 */ @@ -1577,7 +1581,7 @@ 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: /* -- 2.34.1