Author: ian
Date: Sun Mar 9 15:36:56 2014
New Revision: 262950
URL: http://svnweb.freebsd.org/changeset/base/262950
Log:
Make undefined exception entry MPSAFE.
The old code used static storage to preserve a couple registers while
setting up the trapframe for the main handler. Doing so was the last
leftover crumbs from the days when a low-level debugger was hooked into
the exception entry code.
Now the exception entry sequence is essentially the same as for the
other exceptions, which still involves needlessly indirecting through
a function pointer which points to the same code on every platform.
Removing that indirection will be handled as a separate cleanup.
This work is based on an analysis by Juergen Weiss.
Modified:
head/sys/arm/arm/exception.S
head/sys/arm/arm/undefined.c
Modified: head/sys/arm/arm/exception.S
==============================================================================
--- head/sys/arm/arm/exception.S Sun Mar 9 14:54:05 2014
(r262949)
+++ head/sys/arm/arm/exception.S Sun Mar 9 15:36:56 2014
(r262950)
@@ -218,46 +218,25 @@ END(exception_exit)
* look like direct entry from the vector.
*/
ASENTRY_NP(undefined_entry)
- stmfd sp!, {r0, r1}
- ldr r0, Lundefined_handler_indirection
- ldr r1, [sp], #0x0004
- str r1, [r0, #0x0000]
- ldr r1, [sp], #0x0004
- str r1, [r0, #0x0004]
- ldmia r0, {r0, r1, pc}
-
-Lundefined_handler_indirection:
- .word Lundefined_handler_indirection_data
+ sub lr, lr, #0x00000004 /* Adjust the lr */
+ PUSHFRAMEINSVC /* Push trap frame and switch */
+ /* to SVC32 mode */
+ ldr r1, Lundefined_handler_address
+ adr lr, exception_exit
+ mov r0, sp /* pass the stack pointer as r0 */
+ ldr pc, [r1]
END(undefined_entry)
-/*
- * assembly bounce code for calling the kernel
- * undefined instruction handler. This uses
- * a standard trap frame and is called in SVC mode.
- */
-
-ENTRY_NP(undefinedinstruction_bounce)
- PUSHFRAMEINSVC
+ASENTRY_NP(undefinedinstruction_bounce)
+ b undefinedinstruction
+END(undefinedinstruction_bounce)
- mov r0, sp
- adr lr, exception_exit
- b _C_LABEL(undefinedinstruction)
+Lundefined_handler_address:
+ .word _C_LABEL(undefined_handler_address)
.data
- .align 0
-
-/*
- * Indirection data
- * 2 words use for preserving r0 and r1
- * 3rd word contains the undefined handler address.
- */
-
-Lundefined_handler_indirection_data:
- .word 0
- .word 0
-
.global _C_LABEL(undefined_handler_address)
_C_LABEL(undefined_handler_address):
- .word _C_LABEL(undefinedinstruction_bounce)
-END(undefinedinstruction_bounce)
+ .word undefinedinstruction_bounce
+
Modified: head/sys/arm/arm/undefined.c
==============================================================================
--- head/sys/arm/arm/undefined.c Sun Mar 9 14:54:05 2014
(r262949)
+++ head/sys/arm/arm/undefined.c Sun Mar 9 15:36:56 2014
(r262950)
@@ -183,7 +183,6 @@ undefinedinstruction(struct trapframe *f
if (!(frame->tf_spsr & I32_bit))
enable_interrupts(I32_bit|F32_bit);
- frame->tf_pc -= INSN_SIZE;
PCPU_INC(cnt.v_trap);
fault_pc = frame->tf_pc;
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