Fixes objtool warning on write_allowlist() via attribute "cold". #189
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Fixes llnl#188. gcc v8+ can, during compilation, mark code as "cold" that cannot be executed during compliant runs (e.g., executes via undefined behavior). Users can also add the "cold" attribute to functions to indicate they are executed rarely, can be optimized for size rather than speed, and may be placed together with other "cold" functions elsewhere in the binary to improve locality of hot functions. The 4.18 kernel builds an objdump tool that (erroneously?) detects code fallthrough between the write_allowlist() and write_allowlist.cold() functions (and vice versa). Rather than force the use of a more recent objdump, we simple declare the entire function as "cold" for kernels older that v5. The warnings are not present with gcc 15.2.0 and kernel/objdump 6.14.0.
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Fixes #188.
gcc v8+ can, during compilation, mark code as "cold" that cannot be executed during compliant runs (e.g., executes via undefined behavior). Users can also add the "cold" attribute to functions to indicate they are executed rarely, can be optimized for size rather than speed, and may be placed together with other "cold" functions elsewhere in the binary to improve locality of hot functions.
The 4.18 kernel builds an objdump tool that (erroneously?) detects code fallthrough between the write_allowlist() and write_allowlist.cold() functions (and vice versa). Rather than force the use of a more recent objdump, we simple declare the entire function as "cold" for kernels older that v5.
The warnings are not present with gcc 15.2.0 and kernel/objdump 6.14.0.