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Commit efb734d8 authored Mar 29, 2012 by Chris Metcalf

arch/tile: make sure to build memcpy_user_64 without frame pointer



Add a comment explaining why this is important, and add a CFLAGS_REMOVE
clause to the Makefile to make sure it happens.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

parent b287f696

arch/tile/lib/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,7 @@ lib-y = cacheflush.o checksum.o cpumask.o delay.o uaccess.o \
		strchr_$(BITS).o strlen_$(BITS).o

		ifeq ($(CONFIG_TILEGX),y)
		CFLAGS_REMOVE_memcpy_user_64.o = -fno-omit-frame-pointer
		lib-y += memcpy_user_64.o
		else
		lib-y += atomic_32.o atomic_asm_32.o memcpy_tile64.o

arch/tile/lib/memcpy_user_64.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -14,7 +14,13 @@
		* Do memcpy(), but trap and return "n" when a load or store faults.
		*
		* Note: this idiom only works when memcpy() compiles to a leaf function.
		* If "sp" is updated during memcpy, the "jrp lr" will be incorrect.
		* Here leaf function not only means it does not have calls, but also
		* requires no stack operations (sp, stack frame pointer) and no
		* use of callee-saved registers, else "jrp lr" will be incorrect since
		* unwinding stack frame is bypassed. Since memcpy() is not complex so
		* these conditions are satisfied here, but we need to be careful when
		* modifying this file. This is not a clean solution but is the best
		* one so far.
		*
		* Also note that we are capturing "n" from the containing scope here.
		*/