[PATCH v3 1/5] lib: sbi: select expected trap handler per hart
Alvin Chang
alvinga at andestech.com
Sun Aug 30 19:21:56 PDT 2026
Hi Troy,
Have you tried stack protector?
I changed them to use extern symbol directly because they break stack protector.
Please check my patchset sent last year:
https://lore.kernel.org/all/20250703151957.2545958-1-alvinga@andestech.com/
Thanks,
Alvin
On Thu, 27 Aug 2026 17:19:19 +0800, Troy Mitchell wrote:
> The expected trap handler is selected once by the cold boot hart. This
> breaks heterogeneous systems where the cold boot hart implements H but
> another hart does not, because the H-aware handler accesses mtval2 and
> mtinst.
>
> Select the handler from the current hart's MISA at each use so every
> hart uses only the CSRs it implements.
>
> Fixes: 1de66d170e71 ("lib: Optimize unpriv load/store implementation")
> Reported-by: Bo Gan <ganboing at gmail.com>
> Link: https://lore.kernel.org/r/e702f291-dde8-4b99-a65e-182d2b847720@gmail.com
> Suggested-by: Bo Gan <ganboing at gmail.com>
> Signed-off-by: Troy Mitchell <troy.mitchell at linux.spacemit.com>
> Reviewed-by: Bo Gan <ganboing at gmail.com>
> ---
> include/sbi/sbi_csr_detect.h | 4 ++--
> include/sbi/sbi_hart.h | 2 +-
> lib/sbi/sbi_hart.c | 9 +++++----
> lib/sbi/sbi_illegal_atomic.c | 4 ++--
> lib/sbi/sbi_unpriv.c | 6 +++---
> 5 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/include/sbi/sbi_csr_detect.h b/include/sbi/sbi_csr_detect.h
> index 097c31c8..31e50db9 100644
> --- a/include/sbi/sbi_csr_detect.h
> +++ b/include/sbi/sbi_csr_detect.h
> @@ -16,9 +16,9 @@
>
> #define csr_read_allowed(csr_num, trap) \
> ({ \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> register ulong tinfo asm("a3") = (ulong)trap; \
> register ulong ttmp asm("a4"); \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> register ulong ret = 0; \
> ((struct sbi_trap_info *)(trap))->cause = 0; \
> asm volatile( \
> @@ -35,9 +35,9 @@
>
> #define csr_write_allowed(csr_num, trap, value) \
> ({ \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> register ulong tinfo asm("a3") = (ulong)trap; \
> register ulong ttmp asm("a4"); \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> ((struct sbi_trap_info *)(trap))->cause = 0; \
> asm volatile( \
> "add %[ttmp], %[tinfo], zero\n" \
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 543393bb..6f4ee31e 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -135,7 +135,7 @@ struct sbi_scratch;
> int sbi_hart_reinit(struct sbi_scratch *scratch);
> int sbi_hart_init(struct sbi_scratch *scratch, bool cold_boot);
>
> -extern void (*sbi_hart_expected_trap)(void);
> +ulong sbi_hart_expected_trap_addr(void);
>
> unsigned int sbi_hart_mhpm_mask(struct sbi_scratch *scratch);
> void sbi_hart_delegation_dump(struct sbi_scratch *scratch,
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index bee88557..14e44955 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -25,7 +25,11 @@
> extern void __sbi_expected_trap(void);
> extern void __sbi_expected_trap_hext(void);
>
> -void (*sbi_hart_expected_trap)(void) = &__sbi_expected_trap;
> +ulong sbi_hart_expected_trap_addr(void)
> +{
> + return misa_extension('H') ? (ulong)&__sbi_expected_trap_hext :
> + (ulong)&__sbi_expected_trap;
> +}
>
> unsigned long hart_features_offset;
>
> @@ -712,9 +716,6 @@ int sbi_hart_init(struct sbi_scratch *scratch, bool cold_boot)
> csr_write(CSR_MIP, 0);
>
> if (cold_boot) {
> - if (misa_extension('H'))
> - sbi_hart_expected_trap = &__sbi_expected_trap_hext;
> -
> hart_features_offset = sbi_scratch_alloc_offset(
> sizeof(struct sbi_hart_features));
> if (!hart_features_offset)
> diff --git a/lib/sbi/sbi_illegal_atomic.c b/lib/sbi/sbi_illegal_atomic.c
> index 977a9ad0..30f5118e 100644
> --- a/lib/sbi/sbi_illegal_atomic.c
> +++ b/lib/sbi/sbi_illegal_atomic.c
> @@ -30,7 +30,7 @@ int sbi_illegal_atomic(ulong insn, struct sbi_trap_regs *regs)
> { \
> register ulong tinfo asm("a3"); \
> register ulong mstatus = 0; \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> type ret = 0; \
> trap->cause = 0; \
> asm volatile( \
> @@ -57,7 +57,7 @@ int sbi_illegal_atomic(ulong insn, struct sbi_trap_regs *regs)
> { \
> register ulong tinfo asm("a3"); \
> register ulong mstatus = 0; \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> type ret = 0; \
> trap->cause = 0; \
> asm volatile( \
> diff --git a/lib/sbi/sbi_unpriv.c b/lib/sbi/sbi_unpriv.c
> index 60becedc..1550d111 100644
> --- a/lib/sbi/sbi_unpriv.c
> +++ b/lib/sbi/sbi_unpriv.c
> @@ -33,9 +33,9 @@ union sbi_unpriv_data {
> type sbi_load_##type(const type *addr, \
> struct sbi_trap_info *trap) \
> { \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> register ulong tinfo asm("a3") = (ulong)trap; \
> register ulong mstatus = 0; \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> type ret = 0; \
> trap->cause = 0; \
> asm volatile( \
> @@ -58,9 +58,9 @@ union sbi_unpriv_data {
> void sbi_store_##type(type *addr, type val, \
> struct sbi_trap_info *trap) \
> { \
> + register ulong mtvec = sbi_hart_expected_trap_addr(); \
> register ulong tinfo asm("a3") = (ulong)trap; \
> register ulong mstatus = 0; \
> - register ulong mtvec = (ulong)sbi_hart_expected_trap; \
> trap->cause = 0; \
> asm volatile( \
> "csrrw %[mtvec], " STR(CSR_MTVEC) ", %[mtvec]\n" \
> @@ -207,7 +207,7 @@ ulong sbi_get_insn(ulong mepc, struct sbi_trap_info *trap)
> register ulong tinfo asm("a3");
> register ulong ttmp asm("a4");
> register ulong mstatus = 0;
> - register ulong mtvec = (ulong)sbi_hart_expected_trap;
> + register ulong mtvec = sbi_hart_expected_trap_addr();
> ulong insn = 0;
>
> trap->cause = 0;
>
> --
> 2.55.0
>
>
> --
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