From 01dc0386efb769056257410ba5754558384006a7 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 23 Feb 2022 13:02:14 +0100 Subject: module: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC to 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. Cc: Jason Wessel Acked-by: Daniel Thompson Cc: Douglas Anderson Signed-off-by: Christophe Leroy [mcgrof: rebased in light of kernel/module/kdb.c move] Signed-off-by: Luis Chamberlain --- arch/Kconfig | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch') diff --git a/arch/Kconfig b/arch/Kconfig index 29b0167c088b..24945cee808b 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -888,6 +888,12 @@ config MODULES_USE_ELF_REL Modules only use ELF REL relocations. Modules with ELF RELA relocations will give an error. +config ARCH_WANTS_MODULES_DATA_IN_VMALLOC + bool + help + For architectures like powerpc/32 which have constraints on module + allocation and need to allocate module data outside of module area. + config HAVE_IRQ_EXIT_ON_IRQ_STACK bool help -- cgit v1.2.3 From eeaec7801c421e17edda6e45a32d4a5596b633da Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 23 Feb 2022 13:02:16 +0100 Subject: powerpc: Select ARCH_WANTS_MODULES_DATA_IN_VMALLOC on book3s/32 and 8xx book3s/32 and 8xx have a separate area for allocating modules, defined by MODULES_VADDR / MODULES_END. On book3s/32, it is not possible to protect against execution on a page basis. A full 256M segment is either Exec or NoExec. The module area is in an Exec segment while vmalloc area is in a NoExec segment. In order to protect module data against execution, select ARCH_WANTS_MODULES_DATA_IN_VMALLOC. For the 8xx (and possibly other 32 bits platform in the future), there is no such constraint on Exec/NoExec protection, however there is a critical distance between kernel functions and callers that needs to remain below 32Mbytes in order to avoid costly trampolines. By allocating data outside of module area, we increase the chance for module text to remain within acceptable distance from kernel core text. So select ARCH_WANTS_MODULES_DATA_IN_VMALLOC for 8xx as well. Signed-off-by: Christophe Leroy Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Luis Chamberlain --- arch/powerpc/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 174edabb74fa..0b7bcfa63d0d 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -157,6 +157,7 @@ config PPC select ARCH_WANT_IPC_PARSE_VERSION select ARCH_WANT_IRQS_OFF_ACTIVATE_MM select ARCH_WANT_LD_ORPHAN_WARN + select ARCH_WANTS_MODULES_DATA_IN_VMALLOC if PPC_BOOK3S_32 || PPC_8xx select ARCH_WEAK_RELEASE_ACQUIRE select BINFMT_ELF select BUILDTIME_TABLE_SORT -- cgit v1.2.3