On 22 Feb 2022, at 17:27, Andrew Turner <and...@freebsd.org> wrote:
>
> The branch main has been updated by andrew:
>
> URL:
> https://cgit.FreeBSD.org/src/commit/?id=6713be3159000783f7aacf3ea90d6c6878c44da0
>
> commit 6713be3159000783f7aacf3ea90d6c6878c44da0
> Author: Andrew Turner <and...@freebsd.org>
> AuthorDate: 2021-08-30 16:43:22 +0000
> Commit: Andrew Turner <and...@freebsd.org>
> CommitDate: 2022-02-22 17:10:35 +0000
>
> Add NT_ARM_ADDR_MASK
>
> This can be used by debuggers to find which bits in a virtual address
> should be masked off to get a canonical address. This is currently used
> by the Pointer Authentication Code support to get its mask. It could also
> be used if we support Top Byte Ignore for the same purpose.
>
> Reviewed by: kib
> Sponsored by: The FreeBSD Foundation
> Differential Revision: https://reviews.freebsd.org/D34302
This definition seems backwards? In Linux it’s NT_ARM_PAC_MASK, i.e.
the mask for the PAC bits, but you’ve called it NT_ARM_ADDR_MASK here,
which sounds like the mask you apply to get the address bits, but it’s
not, you apply the negation of this mask to get the address bits.
Jess
> ---
> sys/arm64/arm64/elf_machdep.c | 42 ++++++++++++++++++++++++++++++++++++++++--
> sys/arm64/arm64/ptrauth.c | 8 +++++++-
> sys/arm64/include/cpu.h | 3 +++
> sys/arm64/include/reg.h | 5 +++++
> sys/arm64/include/vmparam.h | 3 +++
> sys/sys/elf_common.h | 1 +
> tests/sys/kern/ptrace_test.c | 13 +++++++++++++
> 7 files changed, 72 insertions(+), 3 deletions(-)
>
> diff --git a/sys/arm64/arm64/elf_machdep.c b/sys/arm64/arm64/elf_machdep.c
> index d98512b71e6c..383a0911b7fe 100644
> --- a/sys/arm64/arm64/elf_machdep.c
> +++ b/sys/arm64/arm64/elf_machdep.c
> @@ -59,6 +59,8 @@ __FBSDID("$FreeBSD$");
> u_long __read_frequently elf_hwcap;
> u_long __read_frequently elf_hwcap2;
>
> +struct arm64_addr_mask elf64_addr_mask;
> +
> static struct sysentvec elf64_freebsd_sysvec = {
> .sv_size = SYS_MAXSYSCALL,
> .sv_table = sysent,
> @@ -119,11 +121,47 @@ static Elf64_Brandinfo freebsd_brand_info = {
> SYSINIT(elf64, SI_SUB_EXEC, SI_ORDER_FIRST,
> (sysinit_cfunc_t)elf64_insert_brand_entry, &freebsd_brand_info);
>
> +static bool
> +get_arm64_addr_mask(struct regset *rs, struct thread *td, void *buf,
> + size_t *sizep)
> +{
> + if (buf != NULL) {
> + KASSERT(*sizep == sizeof(elf64_addr_mask),
> + ("%s: invalid size", __func__));
> + memcpy(buf, &elf64_addr_mask, sizeof(elf64_addr_mask));
> + }
> + *sizep = sizeof(elf64_addr_mask);
> +
> + return (true);
> +}
> +
> +static struct regset regset_arm64_addr_mask = {
> + .note = NT_ARM_ADDR_MASK,
> + .size = sizeof(struct arm64_addr_mask),
> + .get = get_arm64_addr_mask,
> +};
> +ELF_REGSET(regset_arm64_addr_mask);
> +
> void
> -elf64_dump_thread(struct thread *td __unused, void *dst __unused,
> - size_t *off __unused)
> +elf64_dump_thread(struct thread *td, void *dst, size_t *off)
> {
> + struct arm64_addr_mask addr_mask;
> + size_t len, mask_size;
> +
> + len = 0;
> + if (dst != NULL) {
> + mask_size = sizeof(addr_mask);
> + get_arm64_addr_mask(®set_arm64_addr_mask, td, &addr_mask,
> + &mask_size);
> +
> + len += elf64_populate_note(NT_ARM_ADDR_MASK, &addr_mask, dst,
> + sizeof(addr_mask), NULL);
> + } else {
> + len += elf64_populate_note(NT_ARM_ADDR_MASK, NULL, NULL,
> + sizeof(addr_mask), NULL);
> + }
>
> + *off += len;
> }
>
> bool
> diff --git a/sys/arm64/arm64/ptrauth.c b/sys/arm64/arm64/ptrauth.c
> index aa0591e351bb..5c129820cd37 100644
> --- a/sys/arm64/arm64/ptrauth.c
> +++ b/sys/arm64/arm64/ptrauth.c
> @@ -46,6 +46,8 @@ __FBSDID("$FreeBSD$");
>
> #include <machine/armreg.h>
> #include <machine/cpu.h>
> +#include <machine/reg.h>
> +#include <machine/vmparam.h>
>
> #define SCTLR_PTRAUTH (SCTLR_EnIA | SCTLR_EnIB | SCTLR_EnDA |
> SCTLR_EnDB)
>
> @@ -82,8 +84,12 @@ ptrauth_init(void)
> * it will also be available on any non-boot CPUs. If this is ever
> * not the case we will have to add a quirk.
> */
> - if (ID_AA64ISAR1_APA_VAL(isar1) > 0 || ID_AA64ISAR1_API_VAL(isar1) > 0)
> + if (ID_AA64ISAR1_APA_VAL(isar1) > 0 ||
> + ID_AA64ISAR1_API_VAL(isar1) > 0) {
> enable_ptrauth = true;
> + elf64_addr_mask.code |= PAC_ADDR_MASK;
> + elf64_addr_mask.data |= PAC_ADDR_MASK;
> + }
> }
>
> /* Copy the keys when forking a new process */
> diff --git a/sys/arm64/include/cpu.h b/sys/arm64/include/cpu.h
> index a6a606b58912..d3b13470a9be 100644
> --- a/sys/arm64/include/cpu.h
> +++ b/sys/arm64/include/cpu.h
> @@ -164,6 +164,9 @@ extern char etext[];
>
> extern uint64_t __cpu_affinity[];
>
> +struct arm64_addr_mask;
> +extern struct arm64_addr_mask elf64_addr_mask;
> +
> void cpu_halt(void) __dead2;
> void cpu_reset(void) __dead2;
> void fork_trampoline(void);
> diff --git a/sys/arm64/include/reg.h b/sys/arm64/include/reg.h
> index bb151af55ba6..44b2e2b21b72 100644
> --- a/sys/arm64/include/reg.h
> +++ b/sys/arm64/include/reg.h
> @@ -83,6 +83,11 @@ struct dbreg32 {
> int dummy;
> };
>
> +struct arm64_addr_mask {
> + __uint64_t code;
> + __uint64_t data;
> +};
> +
> #define __HAVE_REG32
>
> #endif /* !_MACHINE_REG_H_ */
> diff --git a/sys/arm64/include/vmparam.h b/sys/arm64/include/vmparam.h
> index 3e08b0a513b9..483c6d1f91a2 100644
> --- a/sys/arm64/include/vmparam.h
> +++ b/sys/arm64/include/vmparam.h
> @@ -156,6 +156,9 @@
> #define VM_MIN_KERNEL_ADDRESS (0xffff000000000000UL)
> #define VM_MAX_KERNEL_ADDRESS (0xffff008000000000UL)
>
> +/* The address bits that hold a pointer authentication code */
> +#define PAC_ADDR_MASK (0xff7f000000000000UL)
> +
> /* If true addr is in the kernel address space */
> #define ADDR_IS_KERNEL(addr) (((addr) & (1ul << 55)) == (1ul << 55))
> /* If true addr is in its canonical form (i.e. no TBI, PAC, etc.) */
> diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
> index b8629fec8cbc..0bc93659adc5 100644
> --- a/sys/sys/elf_common.h
> +++ b/sys/sys/elf_common.h
> @@ -825,6 +825,7 @@ typedef struct {
> #define NT_PPC_VSX 0x102 /* PowerPC VSX registers */
> #define NT_X86_XSTATE 0x202 /* x86 XSAVE extended state. */
> #define NT_ARM_VFP 0x400 /* ARM VFP registers */
> +#define NT_ARM_ADDR_MASK 0x406 /* arm64 address mask (e.g. for
> TBI) */
>
> /* GNU note types. */
> #define NT_GNU_ABI_TAG 1
> diff --git a/tests/sys/kern/ptrace_test.c b/tests/sys/kern/ptrace_test.c
> index 3e3a445c6152..c62db66fd6f6 100644
> --- a/tests/sys/kern/ptrace_test.c
> +++ b/tests/sys/kern/ptrace_test.c
> @@ -3204,6 +3204,9 @@
> ATF_TC_BODY(ptrace__PT_CONTINUE_with_signal_thread_sigmask, tc)
> ATF_TC_WITHOUT_HEAD(ptrace__PT_REGSET);
> ATF_TC_BODY(ptrace__PT_REGSET, tc)
> {
> +#if defined(__aarch64__)
> + struct arm64_addr_mask addr_mask;
> +#endif
> struct prstatus prstatus;
> struct iovec vec;
> pid_t child, wpid;
> @@ -3242,6 +3245,16 @@ ATF_TC_BODY(ptrace__PT_REGSET, tc)
> ATF_REQUIRE(ptrace(PT_SETREGSET, wpid, (caddr_t)&vec, NT_PRSTATUS) !=
> -1);
>
> +#if defined(__aarch64__)
> + vec.iov_base = &addr_mask;
> + vec.iov_len = sizeof(addr_mask);
> + ATF_REQUIRE(ptrace(PT_GETREGSET, wpid, (caddr_t)&vec,
> + NT_ARM_ADDR_MASK) != -1);
> + REQUIRE_EQ(addr_mask.code, addr_mask.data);
> + ATF_REQUIRE(addr_mask.code == 0 ||
> + addr_mask.code == 0xff7f000000000000UL);
> +#endif
> +
> REQUIRE_EQ(ptrace(PT_CONTINUE, child, (caddr_t)1, 0), 0);
>
> /* The second wait() should report the exit status. */
