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x86: Add pt_regs register and stack access APIs
Add following APIs for accessing registers and stack entries from pt_regs. These APIs are required by kprobes-based event tracer on ftrace. Some other debugging tools might be able to use it too. - regs_query_register_offset(const char *name) Query the offset of "name" register. - regs_query_register_name(unsigned int offset) Query the name of register by its offset. - regs_get_register(struct pt_regs *regs, unsigned int offset) Get the value of a register by its offset. - regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) Check the address is in the kernel stack. - regs_get_kernel_stack_nth(struct pt_regs *reg, unsigned int nth) Get Nth entry of the kernel stack. (N >= 0) - regs_get_argument_nth(struct pt_regs *reg, unsigned int nth) Get Nth argument at function call. (N >= 0) Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: linux-arch@vger.kernel.org Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jason Baron <jbaron@redhat.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it> Cc: Roland McGrath <roland@redhat.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tom Zanussi <tzanussi@gmail.com> Cc: Vegard Nossum <vegard.nossum@gmail.com> LKML-Reference: <20090813203444.31965.26374.stgit@localhost.localdomain> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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2 changed files with 174 additions and 0 deletions
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@ -7,6 +7,7 @@
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#ifdef __KERNEL__
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#include <asm/segment.h>
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#include <asm/page_types.h>
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#endif
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#ifndef __ASSEMBLY__
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@ -216,6 +217,67 @@ static inline unsigned long user_stack_pointer(struct pt_regs *regs)
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return regs->sp;
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}
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/* Query offset/name of register from its name/offset */
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extern int regs_query_register_offset(const char *name);
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extern const char *regs_query_register_name(unsigned int offset);
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#define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
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/**
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* regs_get_register() - get register value from its offset
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* @regs: pt_regs from which register value is gotten.
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* @offset: offset number of the register.
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*
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* regs_get_register returns the value of a register whose offset from @regs
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* is @offset. The @offset is the offset of the register in struct pt_regs.
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* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
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*/
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static inline unsigned long regs_get_register(struct pt_regs *regs,
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unsigned int offset)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return 0;
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return *(unsigned long *)((unsigned long)regs + offset);
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}
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/**
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* regs_within_kernel_stack() - check the address in the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @addr: address which is checked.
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*
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* regs_within_kenel_stack() checks @addr is within the kernel stack page(s).
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* If @addr is within the kernel stack, it returns true. If not, returns false.
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*/
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static inline int regs_within_kernel_stack(struct pt_regs *regs,
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unsigned long addr)
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{
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return ((addr & ~(THREAD_SIZE - 1)) ==
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(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
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}
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/**
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* regs_get_kernel_stack_nth() - get Nth entry of the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @n: stack entry number.
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*
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* regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
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* is specifined by @regs. If the @n th entry is NOT in the kernel stack,
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* this returns 0.
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*/
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static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
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unsigned int n)
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{
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unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
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addr += n;
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if (regs_within_kernel_stack(regs, (unsigned long)addr))
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return *addr;
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else
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return 0;
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}
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/* Get Nth argument at function call */
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extern unsigned long regs_get_argument_nth(struct pt_regs *regs,
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unsigned int n);
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/*
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* These are defined as per linux/ptrace.h, which see.
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*/
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@ -49,6 +49,118 @@ enum x86_regset {
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REGSET_IOPERM32,
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};
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struct pt_regs_offset {
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const char *name;
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int offset;
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};
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#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
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#define REG_OFFSET_END {.name = NULL, .offset = 0}
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static const struct pt_regs_offset regoffset_table[] = {
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#ifdef CONFIG_X86_64
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REG_OFFSET_NAME(r15),
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REG_OFFSET_NAME(r14),
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REG_OFFSET_NAME(r13),
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REG_OFFSET_NAME(r12),
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REG_OFFSET_NAME(r11),
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REG_OFFSET_NAME(r10),
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REG_OFFSET_NAME(r9),
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REG_OFFSET_NAME(r8),
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#endif
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REG_OFFSET_NAME(bx),
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REG_OFFSET_NAME(cx),
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REG_OFFSET_NAME(dx),
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REG_OFFSET_NAME(si),
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REG_OFFSET_NAME(di),
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REG_OFFSET_NAME(bp),
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REG_OFFSET_NAME(ax),
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#ifdef CONFIG_X86_32
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REG_OFFSET_NAME(ds),
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REG_OFFSET_NAME(es),
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REG_OFFSET_NAME(fs),
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REG_OFFSET_NAME(gs),
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#endif
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REG_OFFSET_NAME(orig_ax),
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REG_OFFSET_NAME(ip),
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REG_OFFSET_NAME(cs),
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REG_OFFSET_NAME(flags),
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REG_OFFSET_NAME(sp),
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REG_OFFSET_NAME(ss),
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REG_OFFSET_END,
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};
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/**
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* regs_query_register_offset() - query register offset from its name
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* @name: the name of a register
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*
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* regs_query_register_offset() returns the offset of a register in struct
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* pt_regs from its name. If the name is invalid, this returns -EINVAL;
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*/
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int regs_query_register_offset(const char *name)
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{
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const struct pt_regs_offset *roff;
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for (roff = regoffset_table; roff->name != NULL; roff++)
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if (!strcmp(roff->name, name))
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return roff->offset;
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return -EINVAL;
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}
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/**
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* regs_query_register_name() - query register name from its offset
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* @offset: the offset of a register in struct pt_regs.
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*
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* regs_query_register_name() returns the name of a register from its
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* offset in struct pt_regs. If the @offset is invalid, this returns NULL;
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*/
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const char *regs_query_register_name(unsigned int offset)
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{
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const struct pt_regs_offset *roff;
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for (roff = regoffset_table; roff->name != NULL; roff++)
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if (roff->offset == offset)
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return roff->name;
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return NULL;
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}
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static const int arg_offs_table[] = {
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#ifdef CONFIG_X86_32
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[0] = offsetof(struct pt_regs, ax),
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[1] = offsetof(struct pt_regs, dx),
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[2] = offsetof(struct pt_regs, cx)
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#else /* CONFIG_X86_64 */
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[0] = offsetof(struct pt_regs, di),
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[1] = offsetof(struct pt_regs, si),
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[2] = offsetof(struct pt_regs, dx),
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[3] = offsetof(struct pt_regs, cx),
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[4] = offsetof(struct pt_regs, r8),
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[5] = offsetof(struct pt_regs, r9)
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#endif
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};
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/**
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* regs_get_argument_nth() - get Nth argument at function call
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* @regs: pt_regs which contains registers at function entry.
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* @n: argument number.
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*
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* regs_get_argument_nth() returns @n th argument of a function call.
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* Since usually the kernel stack will be changed right after function entry,
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* you must use this at function entry. If the @n th entry is NOT in the
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* kernel stack or pt_regs, this returns 0.
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*/
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unsigned long regs_get_argument_nth(struct pt_regs *regs, unsigned int n)
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{
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if (n < ARRAY_SIZE(arg_offs_table))
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return *((unsigned long *)regs + arg_offs_table[n]);
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else {
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/*
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* The typical case: arg n is on the stack.
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* (Note: stack[0] = return address, so skip it)
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*/
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n -= ARRAY_SIZE(arg_offs_table);
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return regs_get_kernel_stack_nth(regs, 1 + n);
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}
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}
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/*
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* does not yet catch signals sent when the child dies.
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* in exit.c or in signal.c.
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