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| author | Abner Chang <abner.chang@hpe.com> | 2020-07-16 12:35:32 +0800 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2020-08-12 04:01:39 +0000 |
| commit | e6042aec1bc2bf3a2eaf4f2d3bfe9b90ef95948e (patch) | |
| tree | cf43c75b61bc44abfd78085f592d1e574028c3eb /MdePkg | |
| parent | a3741780fe3535e19e02efa869a7cac481891129 (diff) | |
| download | edk2-e6042aec1bc2bf3a2eaf4f2d3bfe9b90ef95948e.tar.gz | |
BaseLib:Fix RISC-V Supervisor mode (S-Mode) trap handler reentry issue.
While RISC-V hart is trapped into S-Mode, the S-Mode interrupt
CSR (SIE) is disabled by RISC-V hart. However the (SIE) is enabled
again by RestoreTPL, this causes the second S-Mode trap is triggered
by the machine mode (M-Mode)timer interrupt redirection. The SRET
instruction clear Supervisor Previous Privilege (SPP) to zero
(User mode) in the second S-Mode interrupt according to the RISC-V
spec. Above brings hart to the user mode (U-Mode) when execute
SRET in the nested S-Mode interrupt handler because SPP is set to
User Mode in the second interrupt. Afterward, system runs in U-Mode
and any accesses to S-Mode CSR causes the invalid instruction exception.
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Acked-by: Liming Gao <liming.gao@intel.com>
Diffstat (limited to 'MdePkg')
| -rw-r--r-- | MdePkg/Library/BaseLib/RiscV64/RiscVInterrupt.S | 45 |
1 files changed, 38 insertions, 7 deletions
diff --git a/MdePkg/Library/BaseLib/RiscV64/RiscVInterrupt.S b/MdePkg/Library/BaseLib/RiscV64/RiscVInterrupt.S index 766fcfb9cb..87b3468fc7 100644 --- a/MdePkg/Library/BaseLib/RiscV64/RiscVInterrupt.S +++ b/MdePkg/Library/BaseLib/RiscV64/RiscVInterrupt.S @@ -12,21 +12,52 @@ ASM_GLOBAL ASM_PFX(RiscVDisableSupervisorModeInterrupts) ASM_GLOBAL ASM_PFX(RiscVEnableSupervisorModeInterrupt)
ASM_GLOBAL ASM_PFX(RiscVGetSupervisorModeInterrupts)
-# define MSTATUS_SIE 0x00000002
-# define CSR_SSTATUS 0x100
+#define SSTATUS_SIE 0x00000002
+#define CSR_SSTATUS 0x100
+ #define SSTATUS_SPP_BIT_POSITION 8
+//
+// This routine disables supervisor mode interrupt
+//
ASM_PFX(RiscVDisableSupervisorModeInterrupts):
- li a1, MSTATUS_SIE
- csrc CSR_SSTATUS, a1
+ add sp, sp, -(__SIZEOF_POINTER__)
+ sd a1, (sp)
+ li a1, SSTATUS_SIE
+ csrc CSR_SSTATUS, a1
+ ld a1, (sp)
+ add sp, sp, (__SIZEOF_POINTER__)
ret
+//
+// This routine enables supervisor mode interrupt
+//
ASM_PFX(RiscVEnableSupervisorModeInterrupt):
- li a1, MSTATUS_SIE
- csrs CSR_SSTATUS, a1
+ add sp, sp, -2*(__SIZEOF_POINTER__)
+ sd a0, (0*__SIZEOF_POINTER__)(sp)
+ sd a1, (1*__SIZEOF_POINTER__)(sp)
+
+ csrr a0, CSR_SSTATUS
+ and a0, a0, (1 << SSTATUS_SPP_BIT_POSITION)
+ bnez a0, InTrap // We are in supervisor mode (SMode)
+ // trap handler.
+ // Skip enabling SIE becasue SIE
+ // is set to disabled by RISC-V hart
+ // when the trap takes hart to SMode.
+
+ li a1, SSTATUS_SIE
+ csrs CSR_SSTATUS, a1
+InTrap:
+ ld a0, (0*__SIZEOF_POINTER__)(sp)
+ ld a1, (1*__SIZEOF_POINTER__)(sp)
+ add sp, sp, 2*(__SIZEOF_POINTER__)
ret
+//
+// This routine returns supervisor mode interrupt
+// status.
+//
ASM_PFX(RiscVGetSupervisorModeInterrupts):
csrr a0, CSR_SSTATUS
- andi a0, a0, MSTATUS_SIE
+ andi a0, a0, SSTATUS_SIE
ret
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