| Message ID | cover.1643015752.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| Headers | show |
| Series | Allocate module text and data separately | expand |
On Mon, Jan 24, 2022 at 09:22:11AM +0000, Christophe Leroy wrote: > This series allow architectures to request having modules data in > vmalloc area instead of module area. > > This is required on powerpc book3s/32 in order to set data non > executable, because it is not possible to set executability on page > basis, this is done per 256 Mbytes segments. The module area has exec > right, vmalloc area has noexec. > > This can also be useful on other powerpc/32 in order to maximize the > chance of code being close enough to kernel core to avoid branch > trampolines. Am I understanding that this entire effort is for 32-bit powerpc? If so, why such an interest in 32-bit these days? Luis
Le 25/01/2022 à 21:52, Luis Chamberlain a écrit : > On Mon, Jan 24, 2022 at 09:22:11AM +0000, Christophe Leroy wrote: >> This series allow architectures to request having modules data in >> vmalloc area instead of module area. >> >> This is required on powerpc book3s/32 in order to set data non >> executable, because it is not possible to set executability on page >> basis, this is done per 256 Mbytes segments. The module area has exec >> right, vmalloc area has noexec. >> >> This can also be useful on other powerpc/32 in order to maximize the >> chance of code being close enough to kernel core to avoid branch >> trampolines. > > Am I understanding that this entire effort is for 32-bit powerpc? > If so, why such an interest in 32-bit these days? > 32 bit powerpc processors are still manufactured and are widely used in embedded products like internet boxes, small routers, etc ... One of the reason is that there power consumption hence their heat dissipation is way lower than 64 bits variants. I found the effort quite small compared to the benefit it provides. Christophe
This series allow architectures to request having modules data in vmalloc area instead of module area. This is required on powerpc book3s/32 in order to set data non executable, because it is not possible to set executability on page basis, this is done per 256 Mbytes segments. The module area has exec right, vmalloc area has noexec. This can also be useful on other powerpc/32 in order to maximize the chance of code being close enough to kernel core to avoid branch trampolines. Christophe Leroy (7): modules: Refactor within_module_core() and within_module_init() modules: Add within_module_text() macro modules: Always have struct mod_tree_root modules: Prepare for handling several RB trees modules: Introduce data_layout modules: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC powerpc: Select ARCH_WANTS_MODULES_DATA_IN_VMALLOC on book3s/32 and 8xx arch/Kconfig | 6 ++ arch/powerpc/Kconfig | 1 + include/linux/module.h | 38 ++++++- kernel/debug/kdb/kdb_main.c | 10 +- kernel/module.c | 207 ++++++++++++++++++++++++------------ 5 files changed, 186 insertions(+), 76 deletions(-)