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LoongArch: Enable exception fixup for specific ADE subcode

This patch allows the LoongArch BPF JIT to handle recoverable memory
access errors generated by BPF_PROBE_MEM* instructions.

When a BPF program performs memory access operations, the instructions
it executes may trigger ADEM exceptions. The kernel’s built-in BPF
exception table mechanism (EX_TYPE_BPF) will generate corresponding
exception fixup entries in the JIT compilation phase; however, the
architecture-specific trap handling function needs to proactively call
the common fixup routine to achieve exception recovery.

do_ade(): fix EX_TYPE_BPF memory access exceptions for BPF programs,
ensure safe execution.

Relevant test cases: illegal address access tests in module_attach and
subprogs_extable of selftests/bpf.

Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

authored by

Chenghao Duan and committed by
Huacai Chen
9bdc1ab5 4cd641a7

+5
+5
arch/loongarch/kernel/traps.c
··· 535 535 asmlinkage void noinstr do_ade(struct pt_regs *regs) 536 536 { 537 537 irqentry_state_t state = irqentry_enter(regs); 538 + unsigned int esubcode = FIELD_GET(CSR_ESTAT_ESUBCODE, regs->csr_estat); 539 + 540 + if ((esubcode == EXSUBCODE_ADEM) && fixup_exception(regs)) 541 + goto out; 538 542 539 543 die_if_kernel("Kernel ade access", regs); 540 544 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)regs->csr_badvaddr); 541 545 546 + out: 542 547 irqentry_exit(regs, state); 543 548 } 544 549