diff options
| author | Ingo Molnar <mingo@kernel.org> | 2012-04-14 13:18:27 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-04-14 13:19:04 +0200 |
| commit | 6ac1ef482d7ae0c690f1640bf6eb818ff9a2d91e (patch) | |
| tree | 021cc9f6b477146fcebe6f3be4752abfa2ba18a9 /arch/tile/lib/memcpy_user_64.c | |
| parent | 682968e0c425c60f0dde37977e5beb2b12ddc4cc (diff) | |
| parent | a385ec4f11bdcf81af094c03e2444ee9b7fad2e5 (diff) | |
Merge branch 'perf/core' into perf/uprobes
Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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. */ |