mirror/glibc - mirror of git://sourceware.org/git/glibc.git

	Commit message (Collapse)	Author	Age	Files	Lines
*	sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305]	H.J. Lu	2021-02-01	1	-0/+5
\| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \|	Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack space required in order to gurantee successful, non-nested handling of a single signal whose handler is an empty function, and _SC_SIGSTKSZ which is the suggested minimum number of bytes of stack space required for a signal stack. If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel is composed of the following areas and laid out as: ------------------------------ \| alignment padding \| ------------------------------ \| xsave buffer \| ------------------------------ \| fsave header (32-bit only) \| ------------------------------ \| siginfo + ucontext \| ------------------------------ Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave header (32-bit only) + size of siginfo and ucontext + alignment padding. If _SC_SIGSTKSZ_SOURCE or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are redefined as /* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). / # undef SIGSTKSZ # define SIGSTKSZ sysconf (_SC_SIGSTKSZ) / Minimum stack size for a signal handler: SIGSTKSZ. */ # undef MINSIGSTKSZ # define MINSIGSTKSZ SIGSTKSZ Compilation will fail if the source assumes constant MINSIGSTKSZ or SIGSTKSZ. The reason for not simply increasing the kernel's MINSIGSTKSZ #define (apart from the fact that it is rarely used, due to glibc's shadowing definitions) was that userspace binaries will have baked in the old value of the constant and may be making assumptions about it. For example, the type (char [MINSIGSTKSZ]) changes if this #define changes. This could be a problem if an newly built library tries to memcpy() or dump such an object defined by and old binary. Bounds-checking and the stack sizes passed to things like sigaltstack() and makecontext() could similarly go wrong.
*	x86: Remove ARCH_CET_LEGACY_BITMAP [BZ #25397]	H.J. Lu	2020-03-18	1	-5/+0
\| \| \| \| \| \| \| \| \| \| \|	Since legacy bitmap doesn't cover jitted code generated by legacy JIT engine, it isn't very useful. This patch removes ARCH_CET_LEGACY_BITMAP and treats indirect branch tracking similar to shadow stack by removing legacy bitmap support. Tested on CET Linux/x86-64 and non-CET Linux/x86-64. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
*	x86/CET: Extend arch_prctl syscall for CET control	H.J. Lu	2018-07-24	1	-0/+32
	CET arch_prctl bits should be defined in <asm/prctl.h> from Linux kernel header files. Add x86 <include/asm/prctl.h> for pre-CET kernel header files. Note: sysdeps/unix/sysv/linux/x86/include/asm/prctl.h should be removed if <asm/prctl.h> from the required kernel header files contains CET arch_prctl bits. /* CET features: IBT: GNU_PROPERTY_X86_FEATURE_1_IBT SHSTK: GNU_PROPERTY_X86_FEATURE_1_SHSTK / / Return CET features in unsigned long long addr: features: addr[0]. shadow stack base address: addr[1]. shadow stack size: addr[2]. / # define ARCH_CET_STATUS 0x3001 /* Disable CET features in unsigned int features. / # define ARCH_CET_DISABLE 0x3002 / Lock all CET features. / # define ARCH_CET_LOCK 0x3003 / Allocate a new shadow stack with unsigned long long addr: IN: requested shadow stack size: addr. OUT: allocated shadow stack address: addr. / # define ARCH_CET_ALLOC_SHSTK 0x3004 /* Return legacy region bitmap info in unsigned long long addr: address: addr[0]. size: addr[1]. / # define ARCH_CET_LEGACY_BITMAP 0x3005 Reviewed-by: Carlos O'Donell <carlos@redhat.com> * sysdeps/unix/sysv/linux/x86/include/asm/prctl.h: New file. * sysdeps/unix/sysv/linux/x86/cpu-features.c: Include <sys/prctl.h> and <asm/prctl.h>. (get_cet_status): Call arch_prctl with ARCH_CET_STATUS. * sysdeps/unix/sysv/linux/x86/dl-cet.h: Include <sys/prctl.h> and <asm/prctl.h>. (dl_cet_allocate_legacy_bitmap): Call arch_prctl with ARCH_CET_LEGACY_BITMAP. (dl_cet_disable_cet): Call arch_prctl with ARCH_CET_DISABLE. (dl_cet_lock_cet): Call arch_prctl with ARCH_CET_LOCK. * sysdeps/x86/libc-start.c: Include <startup.h>.