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x86/stackframe/32: Provide consistent pt_regs

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Currently pt_regs on x86_32 has an oddity in that kernel regs
(!user_mode(regs)) are short two entries (esp/ss). This means that any
code trying to use them (typically: regs->sp) needs to jump through
some unfortunate hoops.

Change the entry code to fix this up and create a full pt_regs frame.

This then simplifies various trampolines in ftrace and kprobes, the
stack unwinder, ptrace, kdump and kgdb.

Much thanks to Josh for help with the cleanups!

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2019-05-07 23:25:54 +02:00
committed by Ingo Molnar
parent ea1ed38dba
commit 3c88c692c2
15 changed files with 177 additions and 190 deletions
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2
arch/x86/kernel/unwind_orc.c
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@@ -580,7 +580,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
goto done;
state->ip = regs->ip;
state->sp = kernel_stack_pointer(regs);
state->sp = regs->sp;
state->bp = regs->bp;
state->regs = regs;
state->full_regs = true;