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- From 52a747a316042e70a22acb489df9e51bfc6bf2d5 Mon Sep 17 00:00:00 2001
- From: Markus Mayer <mmayer@broadcom.com>
- Date: Fri, 21 Feb 2025 11:19:34 -0800
- Subject: [PATCH] aarch64: define struct user_pac_mask if needed
- On Aarch64, Linux is using Pointer Authentication Code (PAC) for pointer
- authentication.[1] The struct "user_pac_mask" has been part of the Linux
- kernel since version 5.0 as part of this feature. However, older kernels
- do not define it.
- Therefore, we want to check if the definition is present in the kernel
- headers and provide one if it isn't. This ensures two things:
- * elfutils will continue to compile against kernel headers from 4.x
- * binaries built against older kernel headers will still be fully
- functional if used on a newer system
- For reference, the build error that is being avoided looks like this:
- [...]
- CC aarch64_initreg.o
- aarch64_initreg.c: In function 'aarch64_set_initial_registers_tid':
- aarch64_initreg.c:61:24: error: storage size of 'pac_mask' isn't known
- struct user_pac_mask pac_mask;
- ^~~~~~~~
- aarch64_initreg.c:61:24: warning: unused variable 'pac_mask' [-Wunused-variable]
- make[4]: *** [Makefile:831: aarch64_initreg.o] Error 1
- make[3]: *** [Makefile:547: all-recursive] Error 1
- make[2]: *** [Makefile:463: all] Error 2
- [1] https://docs.kernel.org/arch/arm64/pointer-authentication.html
- https://sourceware.org/bugzilla/show_bug.cgi?id=32684
- Fixes: 64e3b451ad2c ("aarch64: extend dwfl_thread_state_registers to handle PAC")
- Signed-off-by: Markus Mayer <mmayer@broadcom.com>
- Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
- Upstream: https://sourceware.org/git/?p=elfutils.git;a=commit;h=52a747a316042e70a22acb489df9e51bfc6bf2d5
- ---
- backends/aarch64_initreg.c | 21 +++++++++++++++++++++
- configure.ac | 8 ++++++++
- 2 files changed, 29 insertions(+)
- diff --git a/backends/aarch64_initreg.c b/backends/aarch64_initreg.c
- index 5ec45ea60..a6badbb45 100644
- --- a/backends/aarch64_initreg.c
- +++ b/backends/aarch64_initreg.c
- @@ -47,6 +47,27 @@
- #define BACKEND aarch64_
- #include "libebl_CPU.h"
-
- +/*
- + * pointer authentication masks (NT_ARM_PAC_MASK)
- + *
- + * Defined by Linux kernel headers since Linux 5.0. Define it here if kernel
- + * headers are older than that, to ensure this file builds regardless.
- + */
- +#if defined(__aarch64__) && defined(__linux__)
- +
- +#ifndef NT_ARM_PAC_MASK
- +#define NT_ARM_PAC_MASK 0x406
- +#endif
- +
- +#ifndef HAVE_USER_PACK_MASK
- +struct user_pac_mask {
- + __u64 data_mask;
- + __u64 insn_mask;
- +};
- +#endif
- +
- +#endif /* __aarch64__ && __linux__ */
- +
- bool
- aarch64_set_initial_registers_tid (pid_t tid __attribute__ ((unused)),
- ebl_tid_registers_t *setfunc __attribute__ ((unused)),
- diff --git a/configure.ac b/configure.ac
- index e57d39275..3298f7fc7 100644
- --- a/configure.ac
- +++ b/configure.ac
- @@ -777,6 +777,14 @@ if test "$sys_user_has_user_regs" = "yes"; then
- [Define to 1 if <sys/user.h> defines struct user_regs_struct])
- fi
-
- +AC_CHECK_TYPE([struct user_pac_mask],
- + [has_user_pac_mask=yes], [has_user_pac_mask=no],
- + [[#include <asm/ptrace.h>]])
- +if test "$has_user_pac_mask" = "yes"; then
- + AC_DEFINE(HAVE_USER_PACK_MASK, 1,
- + [Defined if struct user_pac_mask exists.])
- +fi
- +
- # On a 64-bit host where can can use $CC -m32, we'll run two sets of tests.
- utrace_BIARCH
- CC_BIARCH="$CC $utrace_biarch"
- --
- 2.43.5
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