WANG Xuerui c23e7f01cf LoongArch: Relay BCE exceptions to userland as SIGSEGV with si_code=SEGV_BNDERR ... SEGV_BNDERR was introduced initially for supporting the Intel MPX, but fell into disuse after the MPX support was removed. The LoongArch bounds-checking instructions behave very differently than MPX, but overall the interface is still kind of suitable for conveying the information to userland when bounds-checking assertions trigger, so we wouldn't have to invent more UAPI. Specifically, when the BCE triggers, a SEGV_BNDERR is sent to userland, with si_addr set to the out-of-bounds address or value (in asrt{gt,le}'s case), and one of si_lower or si_upper set to the configured bound depending on the faulting instruction. The other bound is set to either 0 or ULONG_MAX to resemble a range with both lower and upper bounds. Note that it is possible to have si_addr == si_lower in case of a failing asrtgt or {ld,st}gt, because those instructions test for strict greater-than relationship. This should not pose a problem for userland, though, because the faulting PC is available for the application to associate back to the exact instruction for figuring out the expectation. Example exception context generated by a faulting `asrtgt.d t0, t1` (assert t0 > t1 or BCE) with t0=100 and t1=200: > pc 00005555558206a4 ra 00007ffff2d854fc tp 00007ffff2f2f180 sp 00007ffffbf9fb80 > a0 0000000000000002 a1 00007ffffbf9fce8 a2 00007ffffbf9fd00 a3 00007ffff2ed4558 > a4 0000000000000000 a5 00007ffff2f044c8 a6 00007ffffbf9fce0 a7 fffffffffffff000 > t0 0000000000000064 t1 00000000000000c8 t2 00007ffffbfa2d5e t3 00007ffff2f12aa0 > t4 00007ffff2ed6158 t5 00007ffff2ed6158 t6 000000000000002e t7 0000000003d8f538 > t8 0000000000000005 u0 0000000000000000 s9 0000000000000000 s0 00007ffffbf9fce8 > s1 0000000000000002 s2 0000000000000000 s3 00007ffff2f2c038 s4 0000555555820610 > s5 00007ffff2ed5000 s6 0000555555827e38 s7 00007ffffbf9fd00 s8 0000555555827e38 > ra: 00007ffff2d854fc > ERA: 00005555558206a4 > CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE) > PRMD: 00000007 (PPLV3 +PIE -PWE) > EUEN: 00000000 (-FPE -SXE -ASXE -BTE) > ECFG: 0007181c (LIE=2-4,11-12 VS=7) > ESTAT: 000a0000 [BCE] (IS= ECode=10 EsubCode=0) > PRID: 0014c010 (Loongson-64bit, Loongson-3A5000) Signed-off-by: WANG Xuerui <git@xen0n.name> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>		2023-05-01 17:19:27 +08:00
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asm	LoongArch: Relay BCE exceptions to userland as SIGSEGV with si_code=SEGV_BNDERR	2023-05-01 17:19:27 +08:00
uapi/asm	LoongArch: Adjust user_watch_state for explicit alignment	2023-04-19 12:07:27 +08:00