Change Details

Currently the PROCEXEC event only reports a single address, entryaddr, which is the entry point of the interpreter in the typical dynamic case, and used solely to calculate the base address of the interpreter. For PDEs this is fine, since the base address is known from the program headers, but for PIEs the base address varies at run time based on where the kernel chooses to load it, and so pmcstat has no way of knowing the real address ranges for the executable. This was less of an issue in the past since PIEs were rare, but now they're on by default on 64-bit architectures it's more of a problem. To solve this, pass through what was picked for et_dyn_addr by the kernel, and use that as the offset for the executable's start address just as is done for everything in the kernel, and bump the pmc version accordingly. Since we're changing this interface, sanitise the way we determine the interpreter's base address by passing it through directly rather than indirectly via the entry point and having to subtract off whatever the ELF header's e_entry is (and anything that wants the entry point in future can still add that back on as needed; this merely changes the interface to directly provide the underlying variables involved). Also, whilst bumping the version, initialise and check the pm_flags field for CONFIGURELOG so that future changes to the interface can make use of flags instead of a more invasive version bump if appropriate.

Currently the PROCEXEC event only reports a single address, entryaddr, which is the entry point of the interpreter in the typical dynamic case, and used solely to calculate the base address of the interpreter. For PDEs this is fine, since the base address is known from the program headers, but for PIEs the base address varies at run time based on where the kernel chooses to load it, and so pmcstat has no way of knowing the real address ranges for the executable. This was less of an issue in the past since PIEs were rare, but now they're on by default on 64-bit architectures it's more of a problem. To solve this, pass through what was picked for et_dyn_addr by the kernel, and use that as the offset for the executable's start address just as is done for everything in the kernel. Since we're changing this interface, sanitise the way we determine the interpreter's base address by passing it through directly rather than indirectly via the entry point and having to subtract off whatever the ELF header's e_entry is (and anything that wants the entry point in future can still add that back on as needed; this merely changes the interface to directly provide the underlying variables involved). This will be followed up by a bump to the pmc major version.

Currently the PROCEXEC event only reports a single address, entryaddr, which is the entry point of the interpreter in the typical dynamic case, and used solely to calculate the base address of the interpreter. For PDEs this is fine, since the base address is known from the program headers, but for PIEs the base address varies at run time based on where the kernel chooses to load it, and so pmcstat has no way of knowing the real address ranges for the executable. This was less of an issue in the past since PIEs were rare, but now they're on by default on 64-bit architectures it's more of a problem. To solve this, pass through what was picked for et_dyn_addr by the kernel, and use that as the offset for the executable's start address just as is done for everything in the kernel,. and bump the pmc versionSince we're changing this accordingly. Since we're changing this interface, sanitise the way we determine the interpreter's base address determine the interpreter's base address by passing it through directlyby passing it through directly rather than indirectly via the entry rather than indirectly via the entry point and having to subtract offpoint and having to subtract off whatever the ELF header's e_entry is whatever the ELF header's e_(and anything that wants the entry is (and anything that wants the entrypoint in future can still add that point in future can still add that back on as needed; this merely changes the interface to directly provide changes the interface to directly provide the underlying variables involved). Also, whilst bumping the version, initialise and check the pm_flags field for CONFIGURELOG so that future changes to the interface can make use of flags instead of a more invasive version bump if appropriateThis will be followed up by a bump to the pmc major version.