From 61a74ad254628ccd9e88838c3c622885dfb6c588 Mon Sep 17 00:00:00 2001 From: Nylon Chen Date: Fri, 11 Apr 2025 15:38:50 +0800 Subject: [PATCH 1/2] riscv: misaligned: fix sleeping function called during misaligned access handling Use copy_from_user_nofault() and copy_to_user_nofault() instead of copy_from/to_user functions in the misaligned access trap handlers. The following bug report was found when executing misaligned memory accesses: BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:162 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 115, name: two preempt_count: 0, expected: 0 CPU: 0 UID: 0 PID: 115 Comm: two Not tainted 6.14.0-rc5 #24 Hardware name: riscv-virtio,qemu (DT) Call Trace: [] dump_backtrace+0x1c/0x24 [] show_stack+0x28/0x34 [] dump_stack_lvl+0x4a/0x68 [] dump_stack+0x14/0x1c [] __might_resched+0xfa/0x104 [] __might_sleep+0x3e/0x62 [] __might_fault+0x1c/0x24 [] _copy_from_user+0x28/0xaa [] handle_misaligned_store+0x204/0x254 [] do_trap_store_misaligned+0x24/0xee [] handle_exception+0x146/0x152 Fixes: b686ecdeacf6 ("riscv: misaligned: Restrict user access to kernel memory") Fixes: 441381506ba7 ("riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code") Signed-off-by: Zong Li Signed-off-by: Nylon Chen Link: https://lore.kernel.org/r/20250411073850.3699180-3-nylon.chen@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/traps_misaligned.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 4354c87c0376..0173ed80818c 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -441,7 +441,7 @@ static int handle_scalar_misaligned_load(struct pt_regs *regs) val.data_u64 = 0; if (user_mode(regs)) { - if (copy_from_user(&val, (u8 __user *)addr, len)) + if (copy_from_user_nofault(&val, (u8 __user *)addr, len)) return -1; } else { memcpy(&val, (u8 *)addr, len); @@ -539,7 +539,7 @@ static int handle_scalar_misaligned_store(struct pt_regs *regs) return -EOPNOTSUPP; if (user_mode(regs)) { - if (copy_to_user((u8 __user *)addr, &val, len)) + if (copy_to_user_nofault((u8 __user *)addr, &val, len)) return -1; } else { memcpy((u8 *)addr, &val, len); From 7b30b1b04e0d04e56e848c3b9c2952c30de05af9 Mon Sep 17 00:00:00 2001 From: Nylon Chen Date: Fri, 11 Apr 2025 15:38:49 +0800 Subject: [PATCH 2/2] riscv: misaligned: Add handling for ZCB instructions Add support for the Zcb extension's compressed half-word instructions (C.LHU, C.LH, and C.SH) in the RISC-V misaligned access trap handler. Signed-off-by: Zong Li Signed-off-by: Nylon Chen Link: https://lore.kernel.org/r/20250411073850.3699180-2-nylon.chen@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/traps_misaligned.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 0173ed80818c..7443632445d4 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -88,6 +88,13 @@ #define INSN_MATCH_C_FSWSP 0xe002 #define INSN_MASK_C_FSWSP 0xe003 +#define INSN_MATCH_C_LHU 0x8400 +#define INSN_MASK_C_LHU 0xfc43 +#define INSN_MATCH_C_LH 0x8440 +#define INSN_MASK_C_LH 0xfc43 +#define INSN_MATCH_C_SH 0x8c00 +#define INSN_MASK_C_SH 0xfc43 + #define INSN_LEN(insn) ((((insn) & 0x3) < 0x3) ? 2 : 4) #if defined(CONFIG_64BIT) @@ -431,6 +438,13 @@ static int handle_scalar_misaligned_load(struct pt_regs *regs) fp = 1; len = 4; #endif + } else if ((insn & INSN_MASK_C_LHU) == INSN_MATCH_C_LHU) { + len = 2; + insn = RVC_RS2S(insn) << SH_RD; + } else if ((insn & INSN_MASK_C_LH) == INSN_MATCH_C_LH) { + len = 2; + shift = 8 * (sizeof(ulong) - len); + insn = RVC_RS2S(insn) << SH_RD; } else { regs->epc = epc; return -1; @@ -530,6 +544,9 @@ static int handle_scalar_misaligned_store(struct pt_regs *regs) len = 4; val.data_ulong = GET_F32_RS2C(insn, regs); #endif + } else if ((insn & INSN_MASK_C_SH) == INSN_MATCH_C_SH) { + len = 2; + val.data_ulong = GET_RS2S(insn, regs); } else { regs->epc = epc; return -1;