git: 6713be315900 - main - Add NT_ARM_ADDR_MASK

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=6713be3159000783f7aacf3ea90d6c6878c44da0

commit 6713be3159000783f7aacf3ea90d6c6878c44da0
Author:     Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2021-08-30 16:43:22 +0000
Commit:     Andrew Turner <andrew@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
---
 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(&regset_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. */