summaryrefslogtreecommitdiff
path: root/arch/Kconfig
diff options
context:
space:
mode:
authorThomas Gleixner <tglx@linutronix.de>2021-10-21 15:55:05 -0700
committerBorislav Petkov <bp@suse.de>2021-10-26 10:15:12 +0200
commit1bdda24c4af64cd2d65dec5192ab624c5fee7ca0 (patch)
tree9e96250b0947c570a206842a035ad9f79ad0e45e /arch/Kconfig
parent582b01b6ab2714a0a4d554cea7f0d4efeaa2154d (diff)
downloadlwn-1bdda24c4af64cd2d65dec5192ab624c5fee7ca0.tar.gz
lwn-1bdda24c4af64cd2d65dec5192ab624c5fee7ca0.zip
signal: Add an optional check for altstack size
New x86 FPU features will be very large, requiring ~10k of stack in signal handlers. These new features require a new approach called "dynamic features". The kernel currently tries to ensure that altstacks are reasonably sized. Right now, on x86, sys_sigaltstack() requires a size of >=2k. However, that 2k is a constant. Simply raising that 2k requirement to >10k for the new features would break existing apps which have a compiled-in size of 2k. Instead of universally enforcing a larger stack, prohibit a process from using dynamic features without properly-sized altstacks. This must be enforced in two places: * A dynamic feature can not be enabled without an large-enough altstack for each process thread. * Once a dynamic feature is enabled, any request to install a too-small altstack will be rejected The dynamic feature enabling code must examine each thread in a process to ensure that the altstacks are large enough. Add a new lock (sigaltstack_lock()) to ensure that threads can not race and change their altstack after being examined. Add the infrastructure in form of a config option and provide empty stubs for architectures which do not need dynamic altstack size checks. This implementation will be fleshed out for x86 in a future patch called x86/arch_prctl: Add controls for dynamic XSTATE components [dhansen: commit message. ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211021225527.10184-2-chang.seok.bae@intel.com
Diffstat (limited to 'arch/Kconfig')
-rw-r--r--arch/Kconfig3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 8df1c7102643..af5cf3009b4f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1288,6 +1288,9 @@ config ARCH_HAS_ELFCORE_COMPAT
config ARCH_HAS_PARANOID_L1D_FLUSH
bool
+config DYNAMIC_SIGFRAME
+ bool
+
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"