blob: 02713a83204cebf4e7c183f909b7b2289c65eee6 [file] [log] [blame]
#!/usr/bin/env ruby
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require 'digest'
# This is main logic. If you want to add new ucontext-to-pc accessor, add it here
def dwm!(d)
d.template "NetBSD has really nice portable macros", :_UC_MACHINE_PC do |uc|
"_UC_MACHINE_PC(#{uc})"
end
d.with_prefix "uc_mcontext." do
# first arg is ifdef, second is field (with prefix prepended) and third is comment
d.ifdef :REG_PC, "gregs[REG_PC]", "Solaris/x86"
d.ifdef :REG_EIP, "gregs[REG_EIP]", "Linux/i386"
d.ifdef :REG_RIP, "gregs[REG_RIP]", "Linux/amd64"
d.field "sc_ip", "Linux/ia64"
d.field "__pc", "Linux/loongarch64"
d.field "pc", "Linux/{mips,aarch64}"
d.ifdef :PT_NIP, "uc_regs->gregs[PT_NIP]", "Linux/ppc"
d.ifdef :PT_NIP, "gp_regs[PT_NIP]", "Linux/ppc"
d.ifdef :REG_PC, "__gregs[REG_PC]", "Linux/riscv"
d.field "psw.addr", "Linux/s390"
d.field "arm_pc", "Linux/arm (32-bit; legacy)"
d.field "mc_eip", "FreeBSD/i386"
d.field "mc_srr0", "FreeBSD/ppc"
d.field "mc_rip", "FreeBSD/x86_64"
end
d.with_prefix "uc_mcontext->" do
d.field "ss.eip", "OS X (i386, <=10.4)"
d.field "__ss.__eip", "OS X (i386, >=10.5)"
d.field "ss.rip", "OS X (x86_64)"
d.field "__ss.__rip", "OS X (>=10.5 [untested])"
d.field "ss.srr0", "OS X (ppc, ppc64 [untested])"
d.field "__ss.__srr0", "OS X (>=10.5 [untested])"
d.field "__ss.__pc", "OS X (arm64)"
end
d.field "sc_eip", "OpenBSD/i386"
d.field "sc_rip", "OpenBSD/x86_64"
end
# this is generator logic
class Definer
def initialize
@prefix = ""
@accessors = {}
puts(<<HERE)
// -*- eval: (read-only-mode) -*-
// WARNING: this file is autogenerated.
// Change and run src/gen_getpc.rb if you want to
// update. (And submit both files)
// What this file does? We have several possible ways of fetching PC
// (program counter) of signal's ucontext. We explicitly choose to
// avoid ifdef-ing specific OSes (or even specific versions), to
// increase our chances that stuff simply works. Comments below refer
// to OS/architecture combos for documentation purposes, but what
// works is what is used.
// How it does it? It uses lightweight C++ template magic where
// "wrong" ucontext_t{nullptr}-><field access> combos are
// automagically filtered out (via SFINAE).
// Each known case is represented as a template class. For SFINAE
// reasons we masquerade ucontext_t type behind U template
// parameter. And we also parameterize by parent class. This allows us
// to arrange all template instantiations in a single ordered chain of
// inheritance. See RawUCToPC below.
// Note, we do anticipate that most times exactly one of those access
// methods works. But we're prepared there could be several. In
// particular, according to previous comments Solaris/x86 also has
// REG_RIP defined, but it is somehow wrong. So we're careful about
// preserving specific order. We couldn't handle this "multiplicity"
// aspect in pure C++, so we use code generation.
namespace internal {
struct Empty {
#ifdef DEFINE_TRIVIAL_GET
#define HAVE_TRIVIAL_GET
// special thing for stacktrace_generic_fp-inl which wants no-op case
static void* Get(...) {
return nullptr;
}
#endif
};
HERE
end
def with_prefix(prefix)
old_prefix = @prefix
@prefix = @prefix.dup + prefix
yield
ensure
@prefix = old_prefix
end
def ifdef define, field, comment
field field, comment, define
end
def template comment, define = nil, &block
field block, comment, define
end
def field field, comment, define = nil
tmpl = if field.kind_of? Proc
raise unless @prefix.empty?
field
else
proc do |uc|
"#{uc}->#{@prefix + field}"
end
end
fingerprint = Digest::MD5.hexdigest(tmpl["%"] + "@" + comment)[0,8]
maybe_open_ifdef = "\n#ifdef #{define}" if define
maybe_close_ifdef = "\n#endif // #{define}" if define
raise "conflict!" if @accessors.include? fingerprint
if define
@accessors[fingerprint] = comment + " (with #ifdef #{define})"
else
@accessors[fingerprint] = comment
end
puts(<<HERE)
// #{comment}
template <class U, class P, class = void>
struct get_#{fingerprint} : public P {
};#{maybe_open_ifdef}
template <class U, class P>
struct get_#{fingerprint}<U, P, void_t<decltype(#{tmpl["((U*){})"]})>> : public P {
static void* Get(const U* uc) {
// #{comment}
return (void*)(#{tmpl[:uc]});
}
};#{maybe_close_ifdef}
HERE
end
def finalize!
puts
puts(<<HERE)
inline void* RawUCToPC(const ucontext_t* uc) {
HERE
prev = "Empty"
@accessors.each_pair.reverse_each do |(fingerprint, comment)|
puts " // #{comment}"
puts " using g_#{fingerprint} = get_#{fingerprint}<ucontext_t, #{prev}>;"
prev = "g_#{fingerprint}"
end
puts(<<HERE)
return #{prev}::Get(uc);
}
HERE
puts
puts("} // namespace internal")
end
end
path = File.join(File.dirname(__FILE__), "getpc-inl.h")
STDOUT.reopen(IO.popen(["tee", path], "w"))
Definer.new.tap {|instance| dwm!(instance)}.finalize!