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| author |   Mark Rutland <mark.rutland@arm.com> | 2018-12-07 18:39:26 +0000 |
|---|---|---|
| committer |   Will Deacon <will.deacon@arm.com> | 2018-12-13 16:42:46 +0000 |
| commit | ec6e822d1a22d0eef1d1fa260dff751dba9a4258 (patch) | |
| tree | 709322a7fd3dcaa397913e2fbd46f912d19ec9df /include | |
| parent | arm64: add basic pointer authentication support (diff) | |
| download | linux-dev-ec6e822d1a22d0eef1d1fa260dff751dba9a4258.tar.xz linux-dev-ec6e822d1a22d0eef1d1fa260dff751dba9a4258.zip | |
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')
| -rw-r--r-- | include/uapi/linux/elf.h | 1 |
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 */ |