diff options
Diffstat (limited to 'cpukit/score/cpu/aarch64/aarch64-exception-default.S')
| -rw-r--r-- | cpukit/score/cpu/aarch64/aarch64-exception-default.S | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/cpukit/score/cpu/aarch64/aarch64-exception-default.S b/cpukit/score/cpu/aarch64/aarch64-exception-default.S index 81aa82558e..970ccf735f 100644 --- a/cpukit/score/cpu/aarch64/aarch64-exception-default.S +++ b/cpukit/score/cpu/aarch64/aarch64-exception-default.S @@ -54,7 +54,22 @@ /* * This is the exception vector table and the pointers to the default - * exceptions handlers. + * exceptions handlers. Each vector in the table has space for up to 32 + * instructions. The space of the last two instructions in each vector is used + * for the exception handler pointer. + * + * The operation of all exceptions is as follows: + * * An exception occurs + * * A vector is chosen based on the exception type and machine state + * * Execution begins at the chosen vector + * * X0 and LR are pushed onto the current stack + * * An unconditional branch and link is taken to the next instruction to get + * the PC + * * The exception handler pointer (EHP) is retrieved from the current vector using + * the PC + * * Branch and link to the EHP + * * X0 and LR are popped from the current stack after returning from the EHP + * * The exception returns to the previous execution state */ /* |