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authorMark Rutland <mark.rutland@arm.com>2018-12-07 18:39:26 +0000
committerWill Deacon <will.deacon@arm.com>2018-12-13 16:42:46 +0000
commitec6e822d1a22d0eef1d1fa260dff751dba9a4258 (patch)
tree709322a7fd3dcaa397913e2fbd46f912d19ec9df /include/uapi/linux/elf.h
parent7503197562567b57ec14feb3a9d5400ebc56812f (diff)
arm64: expose user PAC bit positions via ptrace
When pointer authentication is in use, data/instruction pointers have a number of PAC bits inserted into them. The number and position of these bits depends on the configured TCR_ELx.TxSZ and whether tagging is enabled. ARMv8.3 allows tagging to differ for instruction and data pointers. For userspace debuggers to unwind the stack and/or to follow pointer chains, they need to be able to remove the PAC bits before attempting to use a pointer. This patch adds a new structure with masks describing the location of the PAC bits in userspace instruction and data pointers (i.e. those addressable via TTBR0), which userspace can query via PTRACE_GETREGSET. By clearing these bits from pointers (and replacing them with the value of bit 55), userspace can acquire the PAC-less versions. This new regset is exposed when the kernel is built with (user) pointer authentication support, and the address authentication feature is enabled. Otherwise, the regset is hidden. Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix to use vabits_user instead of VA_BITS and rename macro] Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'include/uapi/linux/elf.h')
-rw-r--r--include/uapi/linux/elf.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index c5358e0ae7c5..3f23273d690c 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -420,6 +420,7 @@ typedef struct elf64_shdr {
#define NT_ARM_HW_WATCH 0x403 /* ARM hardware watchpoint registers */
#define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
#define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension registers */
+#define NT_ARM_PAC_MASK 0x406 /* ARM pointer authentication code masks */
#define NT_ARC_V2 0x600 /* ARCv2 accumulator/extra registers */
#define NT_VMCOREDD 0x700 /* Vmcore Device Dump Note */
#define NT_MIPS_DSP 0x800 /* MIPS DSP ASE registers */