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Subject[PATCH 02/11] csky: Implement ptrace regs and stack API
Date
From: Guo Ren <ren_guo@c-sky.com>

Needed for kprobes support. Copied and adapted from Patrick's patch,
but it has been modified for csky's pt_regs.

ref:
https://lore.kernel.org/linux-riscv/1572919114-3886-2-git-send-email-vincent.chen@sifive.com/raw

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Patrick Staehlin <me@packi.ch>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
arch/csky/Kconfig | 1 +
arch/csky/include/asm/ptrace.h | 41 +++++++++++++
arch/csky/kernel/ptrace.c | 103 +++++++++++++++++++++++++++++++++
3 files changed, 145 insertions(+)

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 047427f71d83..2dfd3fb07db9 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -48,6 +48,7 @@ config CSKY
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_DMA_CONTIGUOUS
+ select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select MAY_HAVE_SPARSE_IRQ
diff --git a/arch/csky/include/asm/ptrace.h b/arch/csky/include/asm/ptrace.h
index d0aba7b32417..f16ca256e007 100644
--- a/arch/csky/include/asm/ptrace.h
+++ b/arch/csky/include/asm/ptrace.h
@@ -7,6 +7,7 @@
#include <uapi/asm/ptrace.h>
#include <asm/traps.h>
#include <linux/types.h>
+#include <linux/compiler.h>

#ifndef __ASSEMBLY__

@@ -22,6 +23,18 @@
#define instruction_pointer(regs) ((regs)->pc)
#define profile_pc(regs) instruction_pointer(regs)

+static inline void instruction_pointer_set(struct pt_regs *regs,
+ unsigned long val)
+{
+ regs->pc = val;
+}
+
+#if defined(__CSKYABIV2__)
+#define MAX_REG_OFFSET offsetof(struct pt_regs, dcsr)
+#else
+#define MAX_REG_OFFSET offsetof(struct pt_regs, regs[9])
+#endif
+
static inline bool in_syscall(struct pt_regs const *regs)
{
return ((regs->sr >> 16) & 0xff) == VEC_TRAP0;
@@ -37,5 +50,33 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
return regs->a0;
}

+/* Valid only for Kernel mode traps. */
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+ return regs->usp;
+}
+
+extern int regs_query_register_offset(const char *name);
+extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
+ unsigned int n);
+
+/*
+ * regs_get_register() - get register value from its offset
+ * @regs: pt_regs from which register value is gotten
+ * @offset: offset 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 unsigned long regs_get_register(struct pt_regs *regs,
+ unsigned int offset)
+{
+ if (unlikely(offset > MAX_REG_OFFSET))
+ return 0;
+
+ return *(unsigned long *)((unsigned long)regs + offset);
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __ASM_CSKY_PTRACE_H */
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index 313623a19ecb..21ac2608f205 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -193,6 +193,109 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
return &user_csky_view;
}

+struct pt_regs_offset {
+ const char *name;
+ int offset;
+};
+
+#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+static const struct pt_regs_offset regoffset_table[] = {
+ REG_OFFSET_NAME(tls),
+ REG_OFFSET_NAME(lr),
+ REG_OFFSET_NAME(pc),
+ REG_OFFSET_NAME(sr),
+ REG_OFFSET_NAME(usp),
+ REG_OFFSET_NAME(orig_a0),
+ REG_OFFSET_NAME(a0),
+ REG_OFFSET_NAME(a1),
+ REG_OFFSET_NAME(a2),
+ REG_OFFSET_NAME(a3),
+ REG_OFFSET_NAME(regs[0]),
+ REG_OFFSET_NAME(regs[1]),
+ REG_OFFSET_NAME(regs[2]),
+ REG_OFFSET_NAME(regs[3]),
+ REG_OFFSET_NAME(regs[4]),
+ REG_OFFSET_NAME(regs[5]),
+ REG_OFFSET_NAME(regs[6]),
+ REG_OFFSET_NAME(regs[7]),
+ REG_OFFSET_NAME(regs[8]),
+ REG_OFFSET_NAME(regs[9]),
+#if defined(__CSKYABIV2__)
+ REG_OFFSET_NAME(exregs[0]),
+ REG_OFFSET_NAME(exregs[1]),
+ REG_OFFSET_NAME(exregs[2]),
+ REG_OFFSET_NAME(exregs[3]),
+ REG_OFFSET_NAME(exregs[4]),
+ REG_OFFSET_NAME(exregs[5]),
+ REG_OFFSET_NAME(exregs[6]),
+ REG_OFFSET_NAME(exregs[7]),
+ REG_OFFSET_NAME(exregs[8]),
+ REG_OFFSET_NAME(exregs[9]),
+ REG_OFFSET_NAME(exregs[10]),
+ REG_OFFSET_NAME(exregs[11]),
+ REG_OFFSET_NAME(exregs[12]),
+ REG_OFFSET_NAME(exregs[13]),
+ REG_OFFSET_NAME(exregs[14]),
+ REG_OFFSET_NAME(rhi),
+ REG_OFFSET_NAME(rlo),
+ REG_OFFSET_NAME(dcsr),
+#endif
+ REG_OFFSET_END,
+};
+
+/**
+ * regs_query_register_offset() - query register offset from its name
+ * @name: the name of a register
+ *
+ * regs_query_register_offset() returns the offset of a register in struct
+ * pt_regs from its name. If the name is invalid, this returns -EINVAL;
+ */
+int regs_query_register_offset(const char *name)
+{
+ const struct pt_regs_offset *roff;
+
+ for (roff = regoffset_table; roff->name != NULL; roff++)
+ if (!strcmp(roff->name, name))
+ return roff->offset;
+ return -EINVAL;
+}
+
+/**
+ * regs_within_kernel_stack() - check the address in the stack
+ * @regs: pt_regs which contains kernel stack pointer.
+ * @addr: address which is checked.
+ *
+ * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
+ * If @addr is within the kernel stack, it returns true. If not, returns false.
+ */
+static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
+{
+ return (addr & ~(THREAD_SIZE - 1)) ==
+ (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1));
+}
+
+/**
+ * regs_get_kernel_stack_nth() - get Nth entry of the stack
+ * @regs: pt_regs which contains kernel stack pointer.
+ * @n: stack entry number.
+ *
+ * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
+ * is specified by @regs. If the @n th entry is NOT in the kernel stack,
+ * this returns 0.
+ */
+unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
+{
+ unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
+
+ addr += n;
+ if (regs_within_kernel_stack(regs, (unsigned long)addr))
+ return *addr;
+ else
+ return 0;
+}
+
void ptrace_disable(struct task_struct *child)
{
singlestep_disable(child);
--
2.17.0
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