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| author | Grant Likely <grant.likely@secretlab.ca> | 2012-05-08 11:35:37 -0600 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2012-05-08 11:35:37 -0600 |
| commit | 7b96c686223a5c902d6a59c7d178f3904f0ab757 (patch) | |
| tree | fe328ed56ad3719de3cfebad72ef74e34f1ed92b /arch/tile/lib/memcpy_user_64.c | |
| parent | f141ed65f256ec036c7fba604da6b7c448096ef9 (diff) | |
| parent | d48b97b403d23f6df0b990cee652bdf9a52337a3 (diff) | |
| download | olio-linux-3.10-7b96c686223a5c902d6a59c7d178f3904f0ab757.tar.xz olio-linux-3.10-7b96c686223a5c902d6a59c7d178f3904f0ab757.zip | |
Merge tag 'v3.4-rc6' into gpio/next
Linux 3.4-rc6
Diffstat (limited to 'arch/tile/lib/memcpy_user_64.c')
| -rw-r--r-- | arch/tile/lib/memcpy_user_64.c | 8 |
1 files changed, 7 insertions, 1 deletions
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. */ |