Commit eab9e613 by Jan Beulich Committed by Ingo Molnar

x86-64: Fix CFI data for interrupt frames

The patch titled "x86: Don't use frame pointer to save old stack
on irq entry" did not properly adjust CFI directives, so this
patch is a follow-up to that one.

With the old stack pointer no longer stored in a callee-saved
register (plus some offset), we now have to use a CFA expression
to describe the memory location where it is being found. This
requires the use of .cfi_escape (allowing arbitrary byte streams
to be emitted into .eh_frame), as there is no
.cfi_def_cfa_expression (which also cannot reasonably be
expected, as it would require a full expression parser).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/4E8360200200007800058467@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 parent e05139f2
......@@ -27,6 +27,7 @@
#define CFI_REMEMBER_STATE .cfi_remember_state
#define CFI_RESTORE_STATE .cfi_restore_state
#define CFI_UNDEFINED .cfi_undefined
#define CFI_ESCAPE .cfi_escape
#ifdef CONFIG_AS_CFI_SIGNAL_FRAME
#define CFI_SIGNAL_FRAME .cfi_signal_frame
......@@ -68,6 +69,7 @@
#define CFI_REMEMBER_STATE cfi_ignore
#define CFI_RESTORE_STATE cfi_ignore
#define CFI_UNDEFINED cfi_ignore
#define CFI_ESCAPE cfi_ignore
#define CFI_SIGNAL_FRAME cfi_ignore
#endif
......
......@@ -331,10 +331,15 @@ ENDPROC(native_usergs_sysret64)
1: incl PER_CPU_VAR(irq_count)
jne 2f
mov PER_CPU_VAR(irq_stack_ptr),%rsp
EMPTY_FRAME 0
CFI_DEF_CFA_REGISTER rsi
2: /* Store previous stack value */
pushq %rsi
CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \
0x77 /* DW_OP_breg7 */, 0, \
0x06 /* DW_OP_deref */, \
0x08 /* DW_OP_const1u */, SS+8-RBP, \
0x22 /* DW_OP_plus */
/* We entered an interrupt context - irqs are off: */
TRACE_IRQS_OFF
.endm
......@@ -788,7 +793,6 @@ END(interrupt)
subq $ORIG_RAX-RBP, %rsp
CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
SAVE_ARGS_IRQ
PARTIAL_FRAME 0
call \func
.endm
......@@ -813,10 +817,10 @@ ret_from_intr:
/* Restore saved previous stack */
popq %rsi
leaq 16(%rsi), %rsp
CFI_DEF_CFA_REGISTER rsi
leaq ARGOFFSET-RBP(%rsi), %rsp
CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET -16
CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET
exit_intr:
GET_THREAD_INFO(%rcx)
......
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