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[2/2] RISC-V: Only Check PMP if MMU translation succeeds

Message ID 20190518191323.4907-2-Hesham.Almatary@cl.cam.ac.uk (mailing list archive)
State New, archived
Headers show
Series [1/2] RISC-V: Raise access fault exceptions on PMP violations | expand

Commit Message

Hesham Almatary May 18, 2019, 7:13 p.m. UTC 
The current implementation unnecessarily checks for PMP even if MMU translation
failed. This may trigger a wrong PMP access exception instead of
a page exception.

For example, the very first instruction fetched after the first satp write in
S-Mode will trigger a PMP access fault instead of an instruction fetch page
fault.

This patch prioritises MMU exceptions over PMP exceptions and only checks for
PMP if MMU translation succeeds.

Signed-off-by: Hesham Almatary <hesham.almatary@cl.cam.ac.uk>
---
 target/riscv/cpu_helper.c | 1 +
 1 file changed, 1 insertion(+)

--
2.17.1
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Patch

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index b48de36114..7c7282c680 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -403,6 +403,7 @@  bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                   " prot %d\n", __func__, address, ret, pa, prot);

     if (riscv_feature(env, RISCV_FEATURE_PMP) &&
+        (ret == TRANSLATE_SUCCESS) &&
         !pmp_hart_has_privs(env, pa, TARGET_PAGE_SIZE, 1 << access_type)) {
         pmp_violation = true;
         ret = TRANSLATE_FAIL;