Skip to content

Add quick impl for MP_BC_LOAD_CONST_BYTES which just creates qstr so far... - #36

Merged
dpgeorge merged 1 commit into
micropython:masterfrom
pfalcon:b-string-prefix
Jan 2, 2014
Merged

dpgeorge merged 1 commit into
micropython:masterfrom
pfalcon:b-string-prefix

Conversation

@pfalcon

@pfalcon pfalcon commented Jan 2, 2014

Copy link
Copy Markdown
Contributor

....

This is based on the fact that qstr so far behaves more like byte string
than like Unicode string (for example, "012"[0] returns 48 (int)).

Per thoughts expressed in #22.

…far.

This is based on the fact that qstr so far behaves more like byte string
than like Unicode string (for example, "012"[0] returns 48 (int)).
@pfalcon

pfalcon commented Jan 2, 2014

Copy link
Copy Markdown
Contributor Author

So, now b"123"[0] works as expected.

dpgeorge added a commit that referenced this pull request Jan 2, 2014
Add quick impl for MP_BC_LOAD_CONST_BYTES which just creates qstr so far...
@dpgeorge
dpgeorge merged commit ab21caa into micropython:master Jan 2, 2014
drrk pushed a commit to drrk/micropython that referenced this pull request Jan 22, 2017
tannewt pushed a commit to tannewt/circuitpython that referenced this pull request Jan 21, 2021
WeActStudio pushed a commit to WeActStudio/micropython that referenced this pull request Feb 14, 2021
Add find_circles/rects/get_ression and others.
sidorenkom pushed a commit to sidorenkom/micropython that referenced this pull request Oct 5, 2021
Change screen resolution, otherwise LVGL screen appears too small.
Ignore port 5900.
dpgeorge pushed a commit to neuschaefer/micropython that referenced this pull request Apr 25, 2024
Although the original motivation given for the workaround[1] is correct,
nlr.o and nlrthumb.o are linked with a small enough distance that the
problem does not occur, and the workaround isn't necessary. The distance
between the b instruction and its target (nlr_push_tail) is just 64
bytes[2], well within the ±2046 byte range addressable by an
unconditional branch instruction in Thumb mode.

The workaround induces a relocation in the text section (textrel), which
isn't supported everywhere, notably not on musl-libc[3], where it causes
a crash on start-up. With the workaround removed, micropython works on an
ARMv5T Linux system built with musl-libc.

This commit changes nlrthumb.c to use a direct jump by default, but
leaves the long jump workaround as an option for those cases where it's
actually needed.

[1]: commit dd376a2

Author: Damien George <[email protected]>
Date:   Fri Sep 1 15:25:29 2017 +1000

    py/nlrthumb: Get working again on standard Thumb arch (ie not Thumb2).

    "b" on Thumb might not be long enough for the jump to nlr_push_tail so
    it must be done indirectly.

[2]: Excerpt from objdump -d micropython:

000095c4 <nlr_push_tail>:
    95c4:       b510            push    {r4, lr}
    95c6:       0004            movs    r4, r0
    95c8:       f02d fd42       bl      37050 <mp_thread_get_state>
    95cc:       6943            ldr     r3, [r0, micropython#20]
    95ce:       6023            str     r3, [r4, #0]
    95d0:       6144            str     r4, [r0, micropython#20]
    95d2:       2000            movs    r0, #0
    95d4:       bd10            pop     {r4, pc}

000095d6 <nlr_pop>:
    95d6:       b510            push    {r4, lr}
    95d8:       f02d fd3a       bl      37050 <mp_thread_get_state>
    95dc:       6943            ldr     r3, [r0, micropython#20]
    95de:       681b            ldr     r3, [r3, #0]
    95e0:       6143            str     r3, [r0, micropython#20]
    95e2:       bd10            pop     {r4, pc}

000095e4 <nlr_push>:
    95e4:       60c4            str     r4, [r0, micropython#12]
    95e6:       6105            str     r5, [r0, micropython#16]
    95e8:       6146            str     r6, [r0, micropython#20]
    95ea:       6187            str     r7, [r0, micropython#24]
    95ec:       4641            mov     r1, r8
    95ee:       61c1            str     r1, [r0, micropython#28]
    95f0:       4649            mov     r1, r9
    95f2:       6201            str     r1, [r0, micropython#32]
    95f4:       4651            mov     r1, sl
    95f6:       6241            str     r1, [r0, micropython#36]   @ 0x24
    95f8:       4659            mov     r1, fp
    95fa:       6281            str     r1, [r0, micropython#40]   @ 0x28
    95fc:       4669            mov     r1, sp
    95fe:       62c1            str     r1, [r0, micropython#44]   @ 0x2c
    9600:       4671            mov     r1, lr
    9602:       6081            str     r1, [r0, micropython#8]
    9604:       e7de            b.n     95c4 <nlr_push_tail>

[3]: https://www.openwall.com/lists/musl/2020/09/25/4

Signed-off-by: J. Neuschäfer <[email protected]>
graeme-winter pushed a commit to winter-special-projects/micropython that referenced this pull request Sep 21, 2024
Although the original motivation given for the workaround[1] is correct,
nlr.o and nlrthumb.o are linked with a small enough distance that the
problem does not occur, and the workaround isn't necessary. The distance
between the b instruction and its target (nlr_push_tail) is just 64
bytes[2], well within the ±2046 byte range addressable by an
unconditional branch instruction in Thumb mode.

The workaround induces a relocation in the text section (textrel), which
isn't supported everywhere, notably not on musl-libc[3], where it causes
a crash on start-up. With the workaround removed, micropython works on an
ARMv5T Linux system built with musl-libc.

This commit changes nlrthumb.c to use a direct jump by default, but
leaves the long jump workaround as an option for those cases where it's
actually needed.

[1]: commit dd376a2

Author: Damien George <[email protected]>
Date:   Fri Sep 1 15:25:29 2017 +1000

    py/nlrthumb: Get working again on standard Thumb arch (ie not Thumb2).

    "b" on Thumb might not be long enough for the jump to nlr_push_tail so
    it must be done indirectly.

[2]: Excerpt from objdump -d micropython:

000095c4 <nlr_push_tail>:
    95c4:       b510            push    {r4, lr}
    95c6:       0004            movs    r4, r0
    95c8:       f02d fd42       bl      37050 <mp_thread_get_state>
    95cc:       6943            ldr     r3, [r0, micropython#20]
    95ce:       6023            str     r3, [r4, #0]
    95d0:       6144            str     r4, [r0, micropython#20]
    95d2:       2000            movs    r0, #0
    95d4:       bd10            pop     {r4, pc}

000095d6 <nlr_pop>:
    95d6:       b510            push    {r4, lr}
    95d8:       f02d fd3a       bl      37050 <mp_thread_get_state>
    95dc:       6943            ldr     r3, [r0, micropython#20]
    95de:       681b            ldr     r3, [r3, #0]
    95e0:       6143            str     r3, [r0, micropython#20]
    95e2:       bd10            pop     {r4, pc}

000095e4 <nlr_push>:
    95e4:       60c4            str     r4, [r0, micropython#12]
    95e6:       6105            str     r5, [r0, micropython#16]
    95e8:       6146            str     r6, [r0, micropython#20]
    95ea:       6187            str     r7, [r0, micropython#24]
    95ec:       4641            mov     r1, r8
    95ee:       61c1            str     r1, [r0, micropython#28]
    95f0:       4649            mov     r1, r9
    95f2:       6201            str     r1, [r0, micropython#32]
    95f4:       4651            mov     r1, sl
    95f6:       6241            str     r1, [r0, micropython#36]   @ 0x24
    95f8:       4659            mov     r1, fp
    95fa:       6281            str     r1, [r0, micropython#40]   @ 0x28
    95fc:       4669            mov     r1, sp
    95fe:       62c1            str     r1, [r0, micropython#44]   @ 0x2c
    9600:       4671            mov     r1, lr
    9602:       6081            str     r1, [r0, micropython#8]
    9604:       e7de            b.n     95c4 <nlr_push_tail>

[3]: https://www.openwall.com/lists/musl/2020/09/25/4

Signed-off-by: J. Neuschäfer <[email protected]>
Josverl added a commit to Josverl/micropython that referenced this pull request Feb 20, 2026
…instructions

.github: Add Copilot instructions for repository
Taccart pushed a commit to Taccart/micropython that referenced this pull request May 23, 2026
Although the original motivation given for the workaround[1] is correct,
nlr.o and nlrthumb.o are linked with a small enough distance that the
problem does not occur, and the workaround isn't necessary. The distance
between the b instruction and its target (nlr_push_tail) is just 64
bytes[2], well within the ±2046 byte range addressable by an
unconditional branch instruction in Thumb mode.

The workaround induces a relocation in the text section (textrel), which
isn't supported everywhere, notably not on musl-libc[3], where it causes
a crash on start-up. With the workaround removed, micropython works on an
ARMv5T Linux system built with musl-libc.

This commit changes nlrthumb.c to use a direct jump by default, but
leaves the long jump workaround as an option for those cases where it's
actually needed.

[1]: commit dd376a2

Author: Damien George <[email protected]>
Date:   Fri Sep 1 15:25:29 2017 +1000

    py/nlrthumb: Get working again on standard Thumb arch (ie not Thumb2).

    "b" on Thumb might not be long enough for the jump to nlr_push_tail so
    it must be done indirectly.

[2]: Excerpt from objdump -d micropython:

000095c4 <nlr_push_tail>:
    95c4:       b510            push    {r4, lr}
    95c6:       0004            movs    r4, r0
    95c8:       f02d fd42       bl      37050 <mp_thread_get_state>
    95cc:       6943            ldr     r3, [r0, micropython#20]
    95ce:       6023            str     r3, [r4, #0]
    95d0:       6144            str     r4, [r0, micropython#20]
    95d2:       2000            movs    r0, #0
    95d4:       bd10            pop     {r4, pc}

000095d6 <nlr_pop>:
    95d6:       b510            push    {r4, lr}
    95d8:       f02d fd3a       bl      37050 <mp_thread_get_state>
    95dc:       6943            ldr     r3, [r0, micropython#20]
    95de:       681b            ldr     r3, [r3, #0]
    95e0:       6143            str     r3, [r0, micropython#20]
    95e2:       bd10            pop     {r4, pc}

000095e4 <nlr_push>:
    95e4:       60c4            str     r4, [r0, micropython#12]
    95e6:       6105            str     r5, [r0, micropython#16]
    95e8:       6146            str     r6, [r0, micropython#20]
    95ea:       6187            str     r7, [r0, micropython#24]
    95ec:       4641            mov     r1, r8
    95ee:       61c1            str     r1, [r0, micropython#28]
    95f0:       4649            mov     r1, r9
    95f2:       6201            str     r1, [r0, micropython#32]
    95f4:       4651            mov     r1, sl
    95f6:       6241            str     r1, [r0, micropython#36]   @ 0x24
    95f8:       4659            mov     r1, fp
    95fa:       6281            str     r1, [r0, micropython#40]   @ 0x28
    95fc:       4669            mov     r1, sp
    95fe:       62c1            str     r1, [r0, micropython#44]   @ 0x2c
    9600:       4671            mov     r1, lr
    9602:       6081            str     r1, [r0, micropython#8]
    9604:       e7de            b.n     95c4 <nlr_push_tail>

[3]: https://www.openwall.com/lists/musl/2020/09/25/4

Signed-off-by: J. Neuschäfer <[email protected]>
jakub-vesely pushed a commit to jakub-vesely/micropython that referenced this pull request Sep 21, 2026
Although the original motivation given for the workaround[1] is correct,
nlr.o and nlrthumb.o are linked with a small enough distance that the
problem does not occur, and the workaround isn't necessary. The distance
between the b instruction and its target (nlr_push_tail) is just 64
bytes[2], well within the ±2046 byte range addressable by an
unconditional branch instruction in Thumb mode.

The workaround induces a relocation in the text section (textrel), which
isn't supported everywhere, notably not on musl-libc[3], where it causes
a crash on start-up. With the workaround removed, micropython works on an
ARMv5T Linux system built with musl-libc.

This commit changes nlrthumb.c to use a direct jump by default, but
leaves the long jump workaround as an option for those cases where it's
actually needed.

[1]: commit 5d4bd95

Author: Damien George <[email protected]>
Date:   Fri Sep 1 15:25:29 2017 +1000

    py/nlrthumb: Get working again on standard Thumb arch (ie not Thumb2).

    "b" on Thumb might not be long enough for the jump to nlr_push_tail so
    it must be done indirectly.

[2]: Excerpt from objdump -d micropython:

000095c4 <nlr_push_tail>:
    95c4:       b510            push    {r4, lr}
    95c6:       0004            movs    r4, r0
    95c8:       f02d fd42       bl      37050 <mp_thread_get_state>
    95cc:       6943            ldr     r3, [r0, micropython#20]
    95ce:       6023            str     r3, [r4, #0]
    95d0:       6144            str     r4, [r0, micropython#20]
    95d2:       2000            movs    r0, #0
    95d4:       bd10            pop     {r4, pc}

000095d6 <nlr_pop>:
    95d6:       b510            push    {r4, lr}
    95d8:       f02d fd3a       bl      37050 <mp_thread_get_state>
    95dc:       6943            ldr     r3, [r0, micropython#20]
    95de:       681b            ldr     r3, [r3, #0]
    95e0:       6143            str     r3, [r0, micropython#20]
    95e2:       bd10            pop     {r4, pc}

000095e4 <nlr_push>:
    95e4:       60c4            str     r4, [r0, micropython#12]
    95e6:       6105            str     r5, [r0, micropython#16]
    95e8:       6146            str     r6, [r0, micropython#20]
    95ea:       6187            str     r7, [r0, micropython#24]
    95ec:       4641            mov     r1, r8
    95ee:       61c1            str     r1, [r0, micropython#28]
    95f0:       4649            mov     r1, r9
    95f2:       6201            str     r1, [r0, micropython#32]
    95f4:       4651            mov     r1, sl
    95f6:       6241            str     r1, [r0, micropython#36]   @ 0x24
    95f8:       4659            mov     r1, fp
    95fa:       6281            str     r1, [r0, micropython#40]   @ 0x28
    95fc:       4669            mov     r1, sp
    95fe:       62c1            str     r1, [r0, micropython#44]   @ 0x2c
    9600:       4671            mov     r1, lr
    9602:       6081            str     r1, [r0, micropython#8]
    9604:       e7de            b.n     95c4 <nlr_push_tail>

[3]: https://www.openwall.com/lists/musl/2020/09/25/4

Signed-off-by: J. Neuschäfer <[email protected]>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants