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authorCatalin Marinas <catalin.marinas@arm.com>2020-03-30 10:29:38 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2020-09-04 12:46:07 +0100
commit18ddbaa02b7a64f4cf3e7e3d4b78b8b70481a17b (patch)
tree4c04afc8aaffa97f4e571209baf05af5752e8aa8 /arch/arm64/lib
parent93f067f6caf5941cc730e99ce72042304e0e6ff5 (diff)
arm64: mte: ptrace: Add PTRACE_{PEEK,POKE}MTETAGS support
Add support for bulk setting/getting of the MTE tags in a tracee's address space at 'addr' in the ptrace() syscall prototype. 'data' points to a struct iovec in the tracer's address space with iov_base representing the address of a tracer's buffer of length iov_len. The tags to be copied to/from the tracer's buffer are stored as one tag per byte. On successfully copying at least one tag, ptrace() returns 0 and updates the tracer's iov_len with the number of tags copied. In case of error, either -EIO or -EFAULT is returned, trying to follow the ptrace() man page. Note that the tag copying functions are not performance critical, therefore they lack optimisations found in typical memory copy routines. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Alan Hayward <Alan.Hayward@arm.com> Cc: Luis Machado <luis.machado@linaro.org> Cc: Omair Javaid <omair.javaid@linaro.org>
Diffstat (limited to 'arch/arm64/lib')
-rw-r--r--arch/arm64/lib/mte.S53
1 files changed, 53 insertions, 0 deletions
diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S
index 3c3d0edbbca3..434f81d9a180 100644
--- a/arch/arm64/lib/mte.S
+++ b/arch/arm64/lib/mte.S
@@ -4,7 +4,9 @@
*/
#include <linux/linkage.h>
+#include <asm/alternative.h>
#include <asm/assembler.h>
+#include <asm/mte.h>
#include <asm/page.h>
#include <asm/sysreg.h>
@@ -51,3 +53,54 @@ SYM_FUNC_START(mte_copy_page_tags)
b.ne 1b
ret
SYM_FUNC_END(mte_copy_page_tags)
+
+/*
+ * Read tags from a user buffer (one tag per byte) and set the corresponding
+ * tags at the given kernel address. Used by PTRACE_POKEMTETAGS.
+ * x0 - kernel address (to)
+ * x1 - user buffer (from)
+ * x2 - number of tags/bytes (n)
+ * Returns:
+ * x0 - number of tags read/set
+ */
+SYM_FUNC_START(mte_copy_tags_from_user)
+ mov x3, x1
+ cbz x2, 2f
+1:
+ uao_user_alternative 2f, ldrb, ldtrb, w4, x1, 0
+ lsl x4, x4, #MTE_TAG_SHIFT
+ stg x4, [x0], #MTE_GRANULE_SIZE
+ add x1, x1, #1
+ subs x2, x2, #1
+ b.ne 1b
+
+ // exception handling and function return
+2: sub x0, x1, x3 // update the number of tags set
+ ret
+SYM_FUNC_END(mte_copy_tags_from_user)
+
+/*
+ * Get the tags from a kernel address range and write the tag values to the
+ * given user buffer (one tag per byte). Used by PTRACE_PEEKMTETAGS.
+ * x0 - user buffer (to)
+ * x1 - kernel address (from)
+ * x2 - number of tags/bytes (n)
+ * Returns:
+ * x0 - number of tags read/set
+ */
+SYM_FUNC_START(mte_copy_tags_to_user)
+ mov x3, x0
+ cbz x2, 2f
+1:
+ ldg x4, [x1]
+ ubfx x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE
+ uao_user_alternative 2f, strb, sttrb, w4, x0, 0
+ add x0, x0, #1
+ add x1, x1, #MTE_GRANULE_SIZE
+ subs x2, x2, #1
+ b.ne 1b
+
+ // exception handling and function return
+2: sub x0, x0, x3 // update the number of tags copied
+ ret
+SYM_FUNC_END(mte_copy_tags_to_user)