diff options
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 4763b3aff1cc..37440caa7370 100644 --- a/arch/tile/lib/memcpy_user_64.c +++ b/arch/tile/lib/memcpy_user_64.c | |||
| @@ -14,7 +14,13 @@ | |||
| 14 | * Do memcpy(), but trap and return "n" when a load or store faults. | 14 | * Do memcpy(), but trap and return "n" when a load or store faults. |
| 15 | * | 15 | * |
| 16 | * Note: this idiom only works when memcpy() compiles to a leaf function. | 16 | * Note: this idiom only works when memcpy() compiles to a leaf function. |
| 17 | * If "sp" is updated during memcpy, the "jrp lr" will be incorrect. | 17 | * Here leaf function not only means it does not have calls, but also |
| 18 | * requires no stack operations (sp, stack frame pointer) and no | ||
| 19 | * use of callee-saved registers, else "jrp lr" will be incorrect since | ||
| 20 | * unwinding stack frame is bypassed. Since memcpy() is not complex so | ||
| 21 | * these conditions are satisfied here, but we need to be careful when | ||
| 22 | * modifying this file. This is not a clean solution but is the best | ||
| 23 | * one so far. | ||
| 18 | * | 24 | * |
| 19 | * Also note that we are capturing "n" from the containing scope here. | 25 | * Also note that we are capturing "n" from the containing scope here. |
| 20 | */ | 26 | */ |