Removes calls to VMPI_setPageProtection from CodeAlloc, and adds a new
protect/unprotect API to CodeAlloc, along with an SPI for the vm to implement
actual page protection.
It is up to the VM to call codeAlloc->protect() before executing jit'd code,
but CodeAlloc will internally call unprotect() before modifying blocks, as code
is generated. If the VM's implementation of allocCodePage allocates memory
as RWX, then the new protection api's can be ignored and the implementations
of markCodeChunkExec/Write can be empty functions.
A flag per code chunk is used so that only modified pages are unprotected and
reprotected.
CodeAlloc never calls VMPI_setPageProtection any more, so platform abstractions
for this can be encapsulated in the CodeAlloc SPI methods.
nanojit/avmplus.cpp was modified to call VMPI_setPageProtection on the platforms
that didn't already allocate code memory as RWX. Since those callsites are platform
specific and the only place we call VMPI_setPageProtection, the code could be further
simplified.
--HG--
extra : convert_revision : 3c9030f46c15cc0f033592db6ba96674e1f5173b
Removes calls to VMPI_setPageProtection from CodeAlloc, and adds a new
protect/unprotect API to CodeAlloc, along with an SPI for the vm to implement
actual page protection.
It is up to the VM to call codeAlloc->protect() before executing jit'd code,
but CodeAlloc will internally call unprotect() before modifying blocks, as code
is generated. If the VM's implementation of allocCodePage allocates memory
as RWX, then the new protection api's can be ignored and the implementations
of markCodeChunkExec/Write can be empty functions.
A flag per code chunk is used so that only modified pages are unprotected and
reprotected.
CodeAlloc never calls VMPI_setPageProtection any more, so platform abstractions
for this can be encapsulated in the CodeAlloc SPI methods.
nanojit/avmplus.cpp was modified to call VMPI_setPageProtection on the platforms
that didn't already allocate code memory as RWX. Since those callsites are platform
specific and the only place we call VMPI_setPageProtection, the code could be further
simplified.
--HG--
extra : convert_revision : a1002278492b012b727550db2fb928faa6bee36b
