* [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file @ 2015-10-02 10:02 Alex Dowad 2015-10-02 10:02 ` [PATCH 2/3] When generating CFI for i386 asm, don't mistake an FDIV instruction for DIV Alex Dowad ` (2 more replies) 0 siblings, 3 replies; 7+ messages in thread From: Alex Dowad @ 2015-10-02 10:02 UTC (permalink / raw) To: musl There is a lot which could be common between i386 and x86_64, but none of it will be useful for any other arch. These should be useful for all archs, however. --- Makefile | 2 +- tools/add-cfi.i386.awk | 27 --------------------------- tools/common.awk | 26 ++++++++++++++++++++++++++ 3 files changed, 27 insertions(+), 28 deletions(-) create mode 100644 tools/common.awk diff --git a/Makefile b/Makefile index 5a6a43b..761482d 100644 --- a/Makefile +++ b/Makefile @@ -122,7 +122,7 @@ $(foreach s,$(wildcard src/*/$(ARCH)*/*.s),$(eval $(call mkasmdep,$(s)))) # Choose invocation of assembler to be used # $(1) is input file, $(2) is output file, $(3) is assembler flags ifeq ($(ADD_CFI),yes) - AS_CMD = LC_ALL=C awk -f tools/add-cfi.$(ARCH).awk $< | $(CC) -x assembler -c -o $@ - + AS_CMD = LC_ALL=C awk -f tools/common.awk -f tools/add-cfi.$(ARCH).awk $< | $(CC) -x assembler -c -o $@ - else AS_CMD = $(CC) -c -o $@ $< endif diff --git a/tools/add-cfi.i386.awk b/tools/add-cfi.i386.awk index 4a4a3b6..b8bdd7f 100644 --- a/tools/add-cfi.i386.awk +++ b/tools/add-cfi.i386.awk @@ -22,33 +22,6 @@ BEGIN { called = "" } -function hex2int(str, i) { - str = tolower(str) - - for (i = 1; i <= 16; i++) { - char = substr("0123456789abcdef", i, 1) - lookup[char] = i-1 - } - - result = 0 - for (i = 1; i <= length(str); i++) { - result = result * 16 - char = substr(str, i, 1) - result = result + lookup[char] - } - return result -} - -function parse_const(str) { - sign = sub(/^-/, "", str) - hex = sub(/^0x/, "", str) - if (hex) - n = hex2int(str) - else - n = str+0 - return sign ? -n : n -} - function get_const1() { # for instructions with 2 operands, get 1st operand (assuming it is constant) match($0, /-?(0x[0-9a-fA-F]+|[0-9]+),/) diff --git a/tools/common.awk b/tools/common.awk new file mode 100644 index 0000000..04482d4 --- /dev/null +++ b/tools/common.awk @@ -0,0 +1,26 @@ +function hex2int(str, i) { + str = tolower(str) + + for (i = 1; i <= 16; i++) { + char = substr("0123456789abcdef", i, 1) + lookup[char] = i-1 + } + + result = 0 + for (i = 1; i <= length(str); i++) { + result = result * 16 + char = substr(str, i, 1) + result = result + lookup[char] + } + return result +} + +function parse_const(str) { + sign = sub(/^-/, "", str) + hex = sub(/^0x/, "", str) + if (hex) + n = hex2int(str) + else + n = str+0 + return sign ? -n : n +} -- 2.0.0.GIT ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 2/3] When generating CFI for i386 asm, don't mistake an FDIV instruction for DIV 2015-10-02 10:02 [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Alex Dowad @ 2015-10-02 10:02 ` Alex Dowad 2015-10-02 10:02 ` [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 Alex Dowad 2015-10-02 10:18 ` [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Rich Felker 2 siblings, 0 replies; 7+ messages in thread From: Alex Dowad @ 2015-10-02 10:02 UTC (permalink / raw) To: musl ...that would cause the script to erroneously conclude that the values of EAX and EDX have been overwritten. Probably won't make a difference, but it's just as well to get it right... --- tools/add-cfi.i386.awk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/add-cfi.i386.awk b/tools/add-cfi.i386.awk index b8bdd7f..2da1899 100644 --- a/tools/add-cfi.i386.awk +++ b/tools/add-cfi.i386.awk @@ -190,7 +190,7 @@ function trashed(register) { } /i?mul [^,]*$/ { trashed("eax"); trashed("edx") } /i?mul %e(ax|bx|cx|dx|si|di|bp),/ { trashed(get_reg1()) } -/i?div/ { trashed("eax"); trashed("edx") } +/^i?div/ { trashed("eax"); trashed("edx") } /(dec|inc|not|neg|pop) %e(ax|bx|cx|dx|si|di|bp)/ { trashed(get_reg()) } /cpuid/ { trashed("eax"); trashed("ebx"); trashed("ecx"); trashed("edx") } -- 2.0.0.GIT ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 2015-10-02 10:02 [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Alex Dowad 2015-10-02 10:02 ` [PATCH 2/3] When generating CFI for i386 asm, don't mistake an FDIV instruction for DIV Alex Dowad @ 2015-10-02 10:02 ` Alex Dowad 2015-10-02 10:19 ` Rich Felker 2015-10-02 10:18 ` [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Rich Felker 2 siblings, 1 reply; 7+ messages in thread From: Alex Dowad @ 2015-10-02 10:02 UTC (permalink / raw) To: musl This makes debugging more pleasant for the odd times when you have to dig into files implemented in x86_64 assembly. It turns out that the parts we care about are almost exactly like i386, except for the register names! --- tools/add-cfi.x86_64.awk | 185 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 185 insertions(+) create mode 100644 tools/add-cfi.x86_64.awk diff --git a/tools/add-cfi.x86_64.awk b/tools/add-cfi.x86_64.awk new file mode 100644 index 0000000..ed53fa5 --- /dev/null +++ b/tools/add-cfi.x86_64.awk @@ -0,0 +1,185 @@ +# Insert GAS CFI directives ("control frame information") into x86-64 asm input + +BEGIN { + # don't put CFI data in the .eh_frame ELF section (which we don't keep) + print ".cfi_sections .debug_frame" + + # only emit CFI directives inside a function + in_function = 0 + + # emit .loc directives with line numbers from original source + printf ".file 1 \"%s\"\n", ARGV[1] + line_number = 0 + + # used to detect "call label; label:" trick + called = "" +} + +function get_const1() { + # for instructions with 2 operands, get 1st operand (assuming it is constant) + match($0, /-?(0x[0-9a-fA-F]+|[0-9]+),/) + return parse_const(substr($0, RSTART, RLENGTH-1)) +} +function get_reg() { + # only use if you already know there is 1 and only 1 register + match($0, /%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/) + return substr($0, RSTART+1, RLENGTH-1) +} +function get_reg1() { + # for instructions with 2 operands, get 1st operand (assuming it is register) + match($0, /%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/) + return substr($0, RSTART+1, RLENGTH-2) +} +function get_reg2() { + # for instructions with 2 operands, get 2nd operand (assuming it is register) + match($0, /,%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/) + return substr($0, RSTART+2, RLENGTH-2) +} + +function adjust_sp_offset(delta) { + if (in_function) + printf ".cfi_adjust_cfa_offset %d\n", delta +} + +{ + line_number = line_number + 1 + + # clean the input up before doing anything else + # delete comments + gsub(/(#|\/\/).*/, "") + + # canonicalize whitespace + gsub(/[ \t]+/, " ") # mawk doesn't understand \s + gsub(/ *, */, ",") + gsub(/ *: */, ": ") + gsub(/ $/, "") + gsub(/^ /, "") +} + +# check for assembler directives which we care about +/^\.(section|data|text)/ { + # a .cfi_startproc/.cfi_endproc pair should be within the same section + # otherwise, clang will choke when generating ELF output + if (in_function) { + print ".cfi_endproc" + in_function = 0 + } +} +/^\.type [a-zA-Z0-9_]+,\@function/ { + functions[substr($2, 1, length($2)-10)] = 1 +} +# not interested in assembler directives beyond this, just pass them through +/^\./ { + print + next +} + +/^[a-zA-Z0-9_]+:/ { + label = substr($1, 1, length($1)-1) # drop trailing : + + if (called == label) { + # note adjustment of stack pointer from "call label; label:" + adjust_sp_offset(8) + } + + if (functions[label]) { + if (in_function) + print ".cfi_endproc" + + in_function = 1 + print ".cfi_startproc" + + for (register in saved) + delete saved[register] + for (register in dirty) + delete dirty[register] + } + + # an instruction may follow on the same line, so continue processing +} + +/^$/ { next } + +{ + called = "" + printf ".loc 1 %d\n", line_number + print +} + +# KEEPING UP WITH THE STACK POINTER +# %rsp should only be adjusted by pushing/popping or adding/subtracting constants +# +/pushl?/ { + adjust_sp_offset(8) +} +/popl?/ { + adjust_sp_offset(-8) +} +/addl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%rsp/ { adjust_sp_offset(-get_const1()) } +/subl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%rsp/ { adjust_sp_offset(get_const1()) } + +/call/ { + if (match($0, /call [0-9]+f/)) # "forward" label + called = substr($0, RSTART+5, RLENGTH-6) + else if (match($0, /call [0-9a-zA-Z_]+/)) + called = substr($0, RSTART+5, RLENGTH-5) +} + +# TRACKING REGISTER VALUES FROM THE PREVIOUS STACK FRAME +# +/pushl? %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { # don't match "push (%reg)" + # if a register is being pushed, and its value has not changed since the + # beginning of this function, the pushed value can be used when printing + # local variables at the next level up the stack + # emit '.cfi_rel_offset' for that + + if (in_function) { + register = get_reg() + if (!saved[register] && !dirty[register]) { + printf ".cfi_rel_offset %s,0\n", register + saved[register] = 1 + } + } +} + +/movl? %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),-?(0x[0-9a-fA-F]+|[0-9]+)?\(%rsp\)/ { + if (in_function) { + register = get_reg() + if (match($0, /-?(0x[0-9a-fA-F]+|[0-9]+)\(%rsp\)/)) { + offset = parse_const(substr($0, RSTART, RLENGTH-6)) + } else { + offset = 0 + } + if (!saved[register] && !dirty[register]) { + printf ".cfi_rel_offset %s,%d\n", register, offset + saved[register] = 1 + } + } +} + +# IF REGISTER VALUES ARE UNCEREMONIOUSLY TRASHED +# ...then we want to know about it. +# +function trashed(register) { + if (in_function && !saved[register] && !dirty[register]) { + printf ".cfi_undefined %s\n", register + } + dirty[register] = 1 +} +# this does NOT exhaustively check for all possible instructions which could +# overwrite a register value inherited from the caller (just the common ones) +/mov.*,%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { trashed(get_reg2()) } +/(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr) %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/ { + trashed(get_reg1()) +} +/i?mul [^,]*$/ { trashed("rax"); trashed("rdx") } +/i?mul %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/ { trashed(get_reg1()) } +/^i?div/ { trashed("rax"); trashed("rdx") } + +/(dec|inc|not|neg|pop) %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { trashed(get_reg()) } +/cpuid/ { trashed("rax"); trashed("rbx"); trashed("rcx"); trashed("rdx") } + +END { + if (in_function) + print ".cfi_endproc" +} -- 2.0.0.GIT ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 2015-10-02 10:02 ` [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 Alex Dowad @ 2015-10-02 10:19 ` Rich Felker 2015-10-02 10:58 ` Alex 0 siblings, 1 reply; 7+ messages in thread From: Rich Felker @ 2015-10-02 10:19 UTC (permalink / raw) To: musl On Fri, Oct 02, 2015 at 12:02:03PM +0200, Alex Dowad wrote: > +# this does NOT exhaustively check for all possible instructions which could > +# overwrite a register value inherited from the caller (just the common ones) > +/mov.*,%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { trashed(get_reg2()) } > +/(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr) %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/ { > + trashed(get_reg1()) > +} This looks wrong but maybe it's already wrong in existing code. Why are you marking the first operand as trashed rather than the second? Rich ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 2015-10-02 10:19 ` Rich Felker @ 2015-10-02 10:58 ` Alex 2015-10-02 11:01 ` Alex 0 siblings, 1 reply; 7+ messages in thread From: Alex @ 2015-10-02 10:58 UTC (permalink / raw) To: musl [-- Attachment #1: Type: text/plain, Size: 703 bytes --] On Fri, Oct 2, 2015 at 12:19 PM, Rich Felker <dalias@libc.org> wrote: > On Fri, Oct 02, 2015 at 12:02:03PM +0200, Alex Dowad wrote: > > +# this does NOT exhaustively check for all possible instructions which > could > > +# overwrite a register value inherited from the caller (just the common > ones) > > +/mov.*,%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { > trashed(get_reg2()) } > > +/(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr) > %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/ { > > + trashed(get_reg1()) > > +} > > This looks wrong but maybe it's already wrong in existing code. Why > are you marking the first operand as trashed rather than the second? You're absolutely right! [-- Attachment #2: Type: text/html, Size: 1083 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 2015-10-02 10:58 ` Alex @ 2015-10-02 11:01 ` Alex 0 siblings, 0 replies; 7+ messages in thread From: Alex @ 2015-10-02 11:01 UTC (permalink / raw) To: musl [-- Attachment #1: Type: text/plain, Size: 1023 bytes --] On Fri, Oct 2, 2015 at 12:58 PM, Alex <alexinbeijing@gmail.com> wrote: > > On Fri, Oct 2, 2015 at 12:19 PM, Rich Felker <dalias@libc.org> wrote: > >> On Fri, Oct 02, 2015 at 12:02:03PM +0200, Alex Dowad wrote: >> > +# this does NOT exhaustively check for all possible instructions which >> could >> > +# overwrite a register value inherited from the caller (just the >> common ones) >> > +/mov.*,%r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { >> trashed(get_reg2()) } >> > +/(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr) >> %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),/ { >> > + trashed(get_reg1()) >> > +} >> >> This looks wrong but maybe it's already wrong in existing code. Why >> are you marking the first operand as trashed rather than the second? > > > You're absolutely right! > I'm pretty sure the reason I made this mistake was because of reading Intel's developer manuals, where they write the destination register as the first operand, and then absentmindedly applying the GNU syntax used by musl. [-- Attachment #2: Type: text/html, Size: 1717 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file 2015-10-02 10:02 [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Alex Dowad 2015-10-02 10:02 ` [PATCH 2/3] When generating CFI for i386 asm, don't mistake an FDIV instruction for DIV Alex Dowad 2015-10-02 10:02 ` [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 Alex Dowad @ 2015-10-02 10:18 ` Rich Felker 2 siblings, 0 replies; 7+ messages in thread From: Rich Felker @ 2015-10-02 10:18 UTC (permalink / raw) To: musl On Fri, Oct 02, 2015 at 12:02:01PM +0200, Alex Dowad wrote: > There is a lot which could be common between i386 and x86_64, but none of it > will be useful for any other arch. These should be useful for all archs, > however. > --- > Makefile | 2 +- > tools/add-cfi.i386.awk | 27 --------------------------- > tools/common.awk | 26 ++++++++++++++++++++++++++ > 3 files changed, 27 insertions(+), 28 deletions(-) > create mode 100644 tools/common.awk > > diff --git a/Makefile b/Makefile > index 5a6a43b..761482d 100644 > --- a/Makefile > +++ b/Makefile > @@ -122,7 +122,7 @@ $(foreach s,$(wildcard src/*/$(ARCH)*/*.s),$(eval $(call mkasmdep,$(s)))) > # Choose invocation of assembler to be used > # $(1) is input file, $(2) is output file, $(3) is assembler flags > ifeq ($(ADD_CFI),yes) > - AS_CMD = LC_ALL=C awk -f tools/add-cfi.$(ARCH).awk $< | $(CC) -x assembler -c -o $@ - > + AS_CMD = LC_ALL=C awk -f tools/common.awk -f tools/add-cfi.$(ARCH).awk $< | $(CC) -x assembler -c -o $@ - Is the name common.awk appropriate? (common to what?) Maybe cfi-common or something that indicates it's for the cfi scripts. Great to see further work on this! Rich ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2015-10-02 11:01 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-10-02 10:02 [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Alex Dowad 2015-10-02 10:02 ` [PATCH 2/3] When generating CFI for i386 asm, don't mistake an FDIV instruction for DIV Alex Dowad 2015-10-02 10:02 ` [PATCH 3/3] Add script to add CFI directives to asm files in debug builds of x86_64 Alex Dowad 2015-10-02 10:19 ` Rich Felker 2015-10-02 10:58 ` Alex 2015-10-02 11:01 ` Alex 2015-10-02 10:18 ` [PATCH 1/3] Pull a couple common AWK functions for CFI scripts into separate file Rich Felker
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