[RFC PATCH v4 02/34] x86, traps: separate set_intr_gate() and cleanup early_trap_init().

From: Wang Nan
Date: Mon Mar 02 2015 - 09:26:03 EST


As early_trap_init() doesn't use IST, replace set_intr_gate_ist() and
set_system_intr_gate_ist() with their standard counterparts.

set_intr_gate() requires a trace_debug symbol which we don't have and
won't use. This patch seprates set_intr_gate() into 2 parts, and uses
base version in early_trap_init().

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
arch/x86/include/asm/desc.h | 7 ++++++-
arch/x86/kernel/traps.c | 20 ++++++++++++--------
2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index a94b82e..a0bf89f 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -376,11 +376,16 @@ static inline void _set_gate(int gate, unsigned type, void *addr,
* Pentium F0 0F bugfix can have resulted in the mapped
* IDT being write-protected.
*/
-#define set_intr_gate(n, addr) \
+#define set_intr_gate_notrace(n, addr) \
do { \
BUG_ON((unsigned)n > 0xFF); \
_set_gate(n, GATE_INTERRUPT, (void *)addr, 0, 0, \
__KERNEL_CS); \
+ } while (0)
+
+#define set_intr_gate(n, addr) \
+ do { \
+ set_intr_gate_notrace(n, addr); \
_trace_set_gate(n, GATE_INTERRUPT, (void *)trace_##addr,\
0, 0, __KERNEL_CS); \
} while (0)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 4281988..9965bd1 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -926,16 +926,20 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
void __init early_trap_init(void)
{
/*
- * Don't set ist to DEBUG_STACK as it doesn't work until TSS is
- * ready in cpu_init() <-- trap_init(). Before trap_init(), CPU
- * runs at ring 0 so it is impossible to hit an invalid stack.
- * Using the original stack works well enough at this early
- * stage. DEBUG_STACK will be equipped after cpu_init() in
+ * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
+ * is ready in cpu_init() <-- trap_init(). Before trap_init(),
+ * CPU runs at ring 0 so it is impossible to hit an invalid
+ * stack. Using the original stack works well enough at this
+ * early stage. DEBUG_STACK will be equipped after cpu_init() in
* trap_init().
+ *
+ * We don't need to set trace_idt_table like set_intr_gate(),
+ * since we don't have trace_debug and it will be reset to
+ * 'debug' in trap_init() by set_intr_gate_ist().
*/
- set_intr_gate_ist(X86_TRAP_DB, &debug, 0);
+ set_intr_gate_notrace(X86_TRAP_DB, debug);
/* int3 can be called from all */
- set_system_intr_gate_ist(X86_TRAP_BP, &int3, 0);
+ set_system_intr_gate(X86_TRAP_BP, &int3);
#ifdef CONFIG_X86_32
set_intr_gate(X86_TRAP_PF, page_fault);
#endif
@@ -1015,7 +1019,7 @@ void __init trap_init(void)

/*
* X86_TRAP_DB and X86_TRAP_BP have been set
- * in early_trap_init(). However, DEBUG_STACK works only after
+ * in early_trap_init(). However, ITS works only after
* cpu_init() loads TSS. See comments in early_trap_init().
*/
set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
--
1.8.4

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