Re: [PATCH v8 1/7] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature
From: David Long
Date: Wed Aug 12 2015 - 23:50:56 EST
On 08/11/15 13:31, Will Deacon wrote:
Hi David,
On Tue, Aug 11, 2015 at 01:52:38AM +0100, David Long wrote:
From: "David A. Long" <dave.long@xxxxxxxxxx>
Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64.
Signed-off-by: David A. Long <dave.long@xxxxxxxxxx>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/ptrace.h | 25 +++++++++++++
arch/arm64/kernel/ptrace.c | 77 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 103 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 318175f..ef5d726 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -70,6 +70,7 @@ config ARM64
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
+ select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RCU_TABLE_FREE
select HAVE_SYSCALL_TRACEPOINTS
select IRQ_DOMAIN
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index d6dd9fd..8f440e9 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -118,6 +118,8 @@ struct pt_regs {
u64 syscallno;
};
+#define MAX_REG_OFFSET (sizeof(struct user_pt_regs) - sizeof(u64))
Can you not use offset_of(struct user_pt_regs, pstate) here?
Yes, "offsetof" actually though. I've just made that change.
+
#define arch_has_single_step() (1)
#ifdef CONFIG_COMPAT
@@ -146,6 +148,29 @@ struct pt_regs {
#define user_stack_pointer(regs) \
(!compat_user_mode(regs) ? (regs)->sp : (regs)->compat_sp)
+/**
+ * regs_get_register() - get register value from its offset
+ * @regs: pt_regs from which register value is gotten
+ * @offset: offset number of the register.
+ *
+ * regs_get_register returns the value of a register whose offset from @regs.
+ * The @offset is the offset of the register in struct pt_regs.
+ * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
+ */
+static inline u64 regs_get_register(struct pt_regs *regs,
+ unsigned int offset)
+{
+ if (unlikely(offset > MAX_REG_OFFSET))
+ return 0;
+ return *(u64 *)((u64)regs + offset);
+}
Is this guaranteed only to be called on kernel-mode regs, or do we need
to deal with compat tasks too?
If I understand the question I think it's fine that it only deals with
kernel-mode registers. The implemenation is functionally similar to the
other five architectures that implement it.
+
+/* Valid only for Kernel mode traps. */
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+ return regs->sp;
+}
+
static inline unsigned long regs_return_value(struct pt_regs *regs)
{
return regs->regs[0];
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index d882b83..f6199a5 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -48,6 +48,83 @@
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
+#define ARM_pstate pstate
+#define ARM_pc pc
+#define ARM_sp sp
+#define ARM_x30 regs[30]
+#define ARM_x29 regs[29]
+#define ARM_x28 regs[28]
+#define ARM_x27 regs[27]
+#define ARM_x26 regs[26]
+#define ARM_x25 regs[25]
+#define ARM_x24 regs[24]
+#define ARM_x23 regs[23]
+#define ARM_x22 regs[22]
+#define ARM_x21 regs[21]
+#define ARM_x20 regs[20]
+#define ARM_x19 regs[19]
+#define ARM_x18 regs[18]
+#define ARM_x17 regs[17]
+#define ARM_x16 regs[16]
+#define ARM_x15 regs[15]
+#define ARM_x14 regs[14]
+#define ARM_x13 regs[13]
+#define ARM_x12 regs[12]
+#define ARM_x11 regs[11]
+#define ARM_x10 regs[10]
+#define ARM_x9 regs[9]
+#define ARM_x8 regs[8]
+#define ARM_x7 regs[7]
+#define ARM_x6 regs[6]
+#define ARM_x5 regs[5]
+#define ARM_x4 regs[4]
+#define ARM_x3 regs[3]
+#define ARM_x2 regs[2]
+#define ARM_x1 regs[1]
+#define ARM_x0 regs[0]
I've said it before, but I really don't like these macros. I'd rather
rework the following REG_OFFSET_NAME to be GPR_OFFSET_NAME which could
prefix the "x" in the name field.
OK, I've ripped that out and replaced REG_OFFSET_NAME with
GPR_OFFSET_NAME, for the numbered registers. I'm using REGS_OFFSET_NAME
(defined for all architectures in my earlier cleanup patch) for the
non-numbered registers.
+
+#define REG_OFFSET_NAME(r) \
+ {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+const struct pt_regs_offset regs_offset_table[] = {
+ REG_OFFSET_NAME(x0),
+ REG_OFFSET_NAME(x1),
+ REG_OFFSET_NAME(x2),
+ REG_OFFSET_NAME(x3),
+ REG_OFFSET_NAME(x4),
+ REG_OFFSET_NAME(x5),
+ REG_OFFSET_NAME(x6),
+ REG_OFFSET_NAME(x7),
+ REG_OFFSET_NAME(x8),
+ REG_OFFSET_NAME(x9),
+ REG_OFFSET_NAME(x10),
+ REG_OFFSET_NAME(x11),
+ REG_OFFSET_NAME(x12),
+ REG_OFFSET_NAME(x13),
+ REG_OFFSET_NAME(x14),
+ REG_OFFSET_NAME(x15),
+ REG_OFFSET_NAME(x16),
+ REG_OFFSET_NAME(x17),
+ REG_OFFSET_NAME(x18),
+ REG_OFFSET_NAME(x19),
+ REG_OFFSET_NAME(x20),
+ REG_OFFSET_NAME(x21),
+ REG_OFFSET_NAME(x22),
+ REG_OFFSET_NAME(x23),
+ REG_OFFSET_NAME(x24),
+ REG_OFFSET_NAME(x25),
+ REG_OFFSET_NAME(x26),
+ REG_OFFSET_NAME(x27),
+ REG_OFFSET_NAME(x28),
+ REG_OFFSET_NAME(x29),
+ REG_OFFSET_NAME(x30),
Does this interact badly with perf tools, which expect to pass "lr" for
x30? (see tools/perf/arch/arm64/include/perf_regs.h).
Possibly, I can test that when I'm back from my short vacation this
week. The lr/x30 thing seems to be a recurring issue. Perhaps it is
best simply to add a reundant entry for x30 as "lr". It's simple enough
to do, although just slightly ugly looking as it would have to be done
without a macro. Would one ever use "x31" in place of "sp"?
Conversions in the other direction would have to use one or the other of
course.
Will
-dl
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/