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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-06-30 12:24:58 +0000 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-06-30 12:27:06 +0000 |
| commit | 33606b41d35115f887ea688b1a16f2ff85bf2fe4 (patch) | |
| tree | 406b2c7b19a087ba437c68f3dbf0b589fa1d6150 /results/scraper/launchpad-without-comments/1641861 | |
| parent | adedf8771bc4de3113041ca21bd4d0d1c0014b6a (diff) | |
| download | emulator-bug-study-33606b41d35115f887ea688b1a16f2ff85bf2fe4.tar.gz emulator-bug-study-33606b41d35115f887ea688b1a16f2ff85bf2fe4.zip | |
add launchpad bug reports without comments
Diffstat (limited to 'results/scraper/launchpad-without-comments/1641861')
| -rw-r--r-- | results/scraper/launchpad-without-comments/1641861 | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/results/scraper/launchpad-without-comments/1641861 b/results/scraper/launchpad-without-comments/1641861 new file mode 100644 index 00000000..265bbce8 --- /dev/null +++ b/results/scraper/launchpad-without-comments/1641861 @@ -0,0 +1,36 @@ +ARM QEMU doesn't enforce that RES0 bits in FPSCR are non-writeable + +Hi all, we systematically tested the QEMU implementation for emulating arm user mode programs. We found that QEMU incorrectly emulate the FPSCR register. The following the proof of code: + +/*********** Beginning of the bug: arm.c **********/ + +int printf(const char *format, ...); +unsigned char i0[0x10]; +unsigned char o[0x10]; +int main() { + int k = 0; + asm("mov r2, %0\n" + "ldr r0, [r2]\n"::"r"((char *)(i0)));; + asm("vmsr fpscr, r0"); + asm("mov r2, %0\n" + "vmrs r4, fpscr\n" + "str r4, [r2]\n"::"r"((char *)(o)));; + for (k = 0; k < 0x10; k++) + printf("%02x", o[0x10 - 1 - k]); + printf("\n"); +} +unsigned char i0[0x10] = {0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x28, 0x1c, 0xc7, 0x01, 0x00, 0x00, 0x00, 0x00}; + +/*********** End fo the bug **********/ + +When the program is compiled into arm binary code and running on a real arm machine, and running in qemu, we have the following result + +$ arm-linux-gnueabihf-gcc arm.c -o arm -static +$ ./arm +000000000000000000000000fff7009f +$ qemu-arm arm +000000000000000000000000ffffffff + +According to the ARM manual, bits[19, 14:13, 6:5] of FPSCR should be reserved as zero. However, arm qemu fails to keep these bits to be zero: these bits can be actually modified in QEMU. + +Thanks! \ No newline at end of file |