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Commit 2a0c4fdb authored by Bernd Schmidt's avatar Bernd Schmidt Committed by Bryan Wu
Browse files

[Blackfin] arch: fix bug - when using trace buffer with CONFIG_MPU enabled. 



There were a couple of problems with the way the trace buffer state
is saved/restored in assembly.  The DEBUG_HWTRACE_SAVE/RESTORE macros
save a value to the stack, which is not immediately obvious; the CPLB
exception code needed changes to load the correct value of the stack
pointer.  The other problem is that the SAVE/RESTORE macros weren't
pushing and popping the value downwards on the stack, but rather moving
it _upwards_, which is of course completely broken.

We also need to make sure there's a matching DEBUG_HWTRACE_RESTORE in
the error case of the CPLB handler.

Signed-off-by: default avatarBernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
parent dbfe44f0

arch/blackfin/mach-common/entry.S

+6 −1
Original line number Diff line number Diff line
@@ -121,10 +121,14 @@ ENTRY(_ex_icplb_miss) 
	(R7:6,P5:4) = [sp++];

	ASTAT = [sp++];

	SAVE_ALL_SYS

	DEBUG_HWTRACE_SAVE(p5, r7)

#ifdef CONFIG_MPU

	/* We must load R1 here, _before_ DEBUG_HWTRACE_SAVE, since that

	 * will change the stack pointer.  */

	R0 = SEQSTAT;

	R1 = SP;

#endif

	DEBUG_HWTRACE_SAVE(p5, r7)

#ifdef CONFIG_MPU

	sp += -12;

	call _cplb_hdr;

	sp += 12;
@@ -191,6 +195,7 @@ ENTRY(_bfin_return_from_exception) 
ENDPROC(_bfin_return_from_exception)



ENTRY(_handle_bad_cplb)

	DEBUG_HWTRACE_RESTORE(p5, r7)

	/* To get here, we just tried and failed to change a CPLB

	 * so, handle things in trap_c (C code), by lowering to

	 * IRQ5, just like we normally do. Since this is not a

include/asm-blackfin/trace.h

+2 −2
Original line number Diff line number Diff line
@@ -62,14 +62,14 @@ extern unsigned long software_trace_buff[]; 
	preg.L = LO(TBUFCTL); \

	preg.H = HI(TBUFCTL); \

	dreg = [preg]; \

	[sp++] = dreg; \

	[--sp] = dreg; \

	dreg = 0x1; \

	[preg] = dreg;



#define trace_buffer_restore(preg, dreg) \

	preg.L = LO(TBUFCTL); \

	preg.H = HI(TBUFCTL); \

	dreg = [sp--]; \

	dreg = [sp++]; \

	[preg] = dreg;



#else /* CONFIG_DEBUG_BFIN_HWTRACE_ON */