Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings

[Arnd Bergmann <arnd@arndb.de>]

On Wed, Mar 1, 2017 at 10:34 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Tue, Oct 11, 2016 at 10:38 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> On Tuesday, October 11, 2016 10:51:46 AM CEST Josh Poimboeuf wrote:
>>>
>>> 3) 0xFC244C03-config:
>>> drivers/scsi/fnic/fnic_main.o: warning: objtool: fnic_log_q_error() falls through to next function fnic_handle_link_event()
>>> drivers/scsi/snic/snic_res.o: warning: objtool: .text: unexpected end of section
>>>
>>> These look like another bad gcc bug which is truncating functions:
>>
>> Same bug for both of them?
>
> I ran into this one again today, after updating to the latest gcc-7.0.1:
>
> drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool:
> rxe_responder()+0xfe: sibling call from callable instruction with
> changed frame pointer
>
> Josh, did you get around to updating objtool the last time I reported it, or
> is it still the same problem? If this is a new variation, I can provide more
> details about the failure, otherwise I'll just ignore it for now.

Actually, something must have changed in gcc since last month, I also
just got a report in another file:

drivers/i2c/busses/i2c-img-scb.o: warning: objtool: img_i2c_probe()
falls through to next function img_i2c_read_fifo()

See below for the relevant snippet from the assembler output.

      Arnd

# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1176:           if
(i2c->bitrate <= timings[i].max_bitrate) {
        movl    1648(%rbx), %edx        # MEM[(struct img_i2c
*)_29].bitrate, _99
        cmpl    timings+8(%rip), %edx   # timings[0].max_bitrate, _99
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1171:
i2c->need_wr_rd_fence = true;
        movb    $1, 1652(%rbx)  #, MEM[(struct img_i2c *)_29].need_wr_rd_fence
        movl    timings+48(%rip), %ecx  # timings[1].max_bitrate, pretmp_260
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1176:           if
(i2c->bitrate <= timings[i].max_bitrate) {
        jbe     .L59    #,
        cmpl    %ecx, %edx      # pretmp_260, _99
        jbe     .L60    #,
.L61:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1182:
dev_warn(i2c->adap.dev.parent,
        movq    240(%rbx), %rdi # MEM[(struct img_i2c
*)_29].adap.dev.parent, MEM[(struct img_i2c *)_29].adap.dev.parent
        movq    $.LC12, %rsi    #,
        call    dev_warn        #
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1187:
i2c->bitrate = timing.max_bitrate;
        movl    timings+48(%rip), %eax  # MEM[(struct img_i2c_timings
*)&timings + 48B], MEM[(struct img_i2c_timings *)&timings + 48B]
        movl    %eax, 1648(%rbx)        # MEM[(struct img_i2c_timings
*)&timings + 48B], MEM[(struct img_i2c *)_29].bitrate
.L60:
        ud2
.L66:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1360:
dev_err(&pdev->dev, "can't request irq %d\n", irq);
        movl    %r13d, %edx     # <retval>,
        movq    $.LC6, %rsi     #,
        movq    %r14, %rdi      # _1,
        call    dev_err #
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1361:           return ret;
        movl    -52(%rbp), %eax # %sfp, _62
        movl    %eax, %r13d     # _62, <retval>
        jmp     .L52    #
.L65:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1341:
dev_err(&pdev->dev, "can't get irq number\n");
        movq    $.LC5, %rsi     #,
        movq    %r14, %rdi      # _1,
        call    dev_err #
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1342:           return irq;
        jmp     .L52    #
.L67:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1162:
dev_info(i2c->adap.dev.parent,
        movzbl  %ah, %ecx       # ret, tmp150
        movq    240(%rbx), %rdi # MEM[(struct img_i2c
*)_29].adap.dev.parent, MEM[(struct img_i2c *)_29].adap.dev.parent
        movl    %eax, %edx      # ret, tmp153
        movl    %ecx, %r8d      # tmp150, tmp150
        movl    %eax, %ecx      # ret, tmp151
        movzbl  %al, %r9d       # ret,
        shrl    $16, %ecx       #, tmp151
        shrl    $24, %edx       #, tmp153
        movq    $.LC11, %rsi    #,
        movzbl  %cl, %ecx       # tmp151, tmp152
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1404:   return ret;
        movl    $-22, %r13d     #, <retval>
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1162:
dev_info(i2c->adap.dev.parent,
        call    _dev_info       #
# /git/arm-soc/include/linux/clk.h:210:         might_sleep();
        xorl    %edx, %edx      #
        movl    $210, %esi      #,
        movq    $.LC0, %rdi     #,
        call    __might_sleep   #
        xorl    %edx, %edx      #
        movl    $210, %esi      #,
        movq    $.LC0, %rdi     #,
        call    __might_sleep   #
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1404:   return ret;
        jmp     .L52    #
.L62:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1332:           return -ENOMEM;
        movl    $-12, %r13d     #, <retval>
        jmp     .L52    #
.L59:
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:1181:   if
(i2c->bitrate > timings[ARRAY_SIZE(timings) - 1].max_bitrate) {
        cmpl    %ecx, %edx      # pretmp_260, _99
        ja      .L61    #,
        ud2
        .size   img_i2c_probe, .-img_i2c_probe


        .p2align 4,,15
        .type   img_i2c_read_fifo, @function
img_i2c_read_fifo:
1:      call    __fentry__
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:545:    while (i2c->msg.len) {
        cmpw    $0, 1828(%rdi)  #, i2c_10(D)->msg.len
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:544: {
        pushq   %rbp    #
        movq    %rsp, %rbp      #,
# /git/arm-soc/drivers/i2c/busses/i2c-img-scb.c:545:    while (i2c->msg.len) {
        je      .L68    #,
# /git/arm-soc/arch/x86/include/asm/io.h:66: build_mmio_write(writel,
"l", unsigned int, "r", :"memory")
        xorl    %esi, %esi      # tmp118
        movl    $255, %ecx      #, tmp119
        jmp     .L71    #