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riscv: pmp: switch over to the new implementation

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Add the appropriate hooks effectively replacing the old implementation
with the new one.

Also the stackguard wasn't properly enforced especially with the
usermode combination. This is now fixed.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2022-04-06 22:03:54 -04:00 • committed by Carles Cufí
commit 2fece49a14
9 changed files with 118 additions and 50 deletions
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52
arch/riscv/core/isr.S
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@ -246,11 +246,6 @@ skip_store_fp_caller_saved:
/* If a0 != 0, jump to is_interrupt */
bnez a0, is_interrupt
#ifdef CONFIG_PMP_STACK_GUARD
li t0, MSTATUS_MPRV
csrs mstatus, t0
#endif
/*
* If the exception is the result of an ECALL, check whether to
* perform a context-switch or an IRQ offload. Otherwise call _Fault
@ -301,6 +296,14 @@ is_kernel_syscall:
addi t0, t0, 4
sr t0, __z_arch_esf_t_mepc_OFFSET(sp)
#ifdef CONFIG_PMP_STACK_GUARD
/* Re-activate PMP for m-mode */
li t1, MSTATUS_MPP
csrc mstatus, t1
li t1, MSTATUS_MPRV
csrs mstatus, t1
#endif
/* Determine what to do. Operation code is in a7. */
lr a7, __z_arch_esf_t_a7_OFFSET(sp)
@ -356,6 +359,16 @@ do_irq_offload:
#ifdef CONFIG_USERSPACE
is_user_syscall:
#ifdef CONFIG_PMP_STACK_GUARD
/*
* We came from userspace and need to reconfigure the
* PMP for kernel mode stack guard.
*/
lr a0, ___cpu_t_current_OFFSET(s0)
call z_riscv_pmp_stackguard_enable
#endif
/* It is safe to re-enable IRQs now */
csrs mstatus, MSTATUS_IEN
@ -405,6 +418,29 @@ valid_syscall_id:
#endif /* CONFIG_USERSPACE */
is_interrupt:
#ifdef CONFIG_PMP_STACK_GUARD
#ifdef CONFIG_USERSPACE
/*
* If we came from userspace then we need to reconfigure the
* PMP for kernel mode stack guard.
*/
lr t0, __z_arch_esf_t_mstatus_OFFSET(sp)
li t1, MSTATUS_MPP
and t0, t0, t1
bnez t0, 1f
lr a0, ___cpu_t_current_OFFSET(s0)
call z_riscv_pmp_stackguard_enable
j 2f
#endif /* CONFIG_USERSPACE */
1: /* Re-activate PMP for m-mode */
li t1, MSTATUS_MPP
csrc mstatus, t1
li t1, MSTATUS_MPRV
csrs mstatus, t1
2:
#endif
/* Increment _current_cpu->nested */
lw t3, ___cpu_t_nested_OFFSET(s0)
addi t4, t3, 1
@ -547,6 +583,12 @@ no_fp: /* make sure this is reflected in the restored mstatus */
and t0, t4, t1
bnez t0, 1f
#ifdef CONFIG_PMP_STACK_GUARD
/* Remove kernel stack guard and Reconfigure PMP for user mode */
lr a0, ___cpu_t_current_OFFSET(s0)
call z_riscv_pmp_usermode_enable
#endif
#if !defined(CONFIG_SMP)
/* Set user mode variable */
li t0, 1