diff options
| author | Chris Metcalf <cmetcalf@tilera.com> | 2012-03-29 14:05:04 -0400 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2012-04-02 12:12:42 -0400 |
| commit | efb734d8ed040b053f53fd53589ed5d9c9b5cd04 (patch) | |
| tree | 6f001ff457da8e8a2020f3c3ec5f7cf7c9e561ff /arch/tile/lib | |
| parent | b287f69676a34a9fc341de4d79a9c74e1959dec6 (diff) | |
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>
Diffstat (limited to 'arch/tile/lib')
| -rw-r--r-- | arch/tile/lib/Makefile | 1 | ||||
| -rw-r--r-- | arch/tile/lib/memcpy_user_64.c | 8 |
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/tile/lib/Makefile b/arch/tile/lib/Makefile index 0c26086ecbe..985f5985823 100644 --- a/arch/tile/lib/Makefile +++ b/arch/tile/lib/Makefile @@ -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 diff --git a/arch/tile/lib/memcpy_user_64.c b/arch/tile/lib/memcpy_user_64.c index 4763b3aff1c..37440caa737 100644 --- a/arch/tile/lib/memcpy_user_64.c +++ b/arch/tile/lib/memcpy_user_64.c @@ -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. */ |