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authorAnton Blanchard <anton@samba.org>2013-05-01 20:06:33 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-05-06 09:25:35 +1000
commit73d2fb758e678c93bc76d40876c2359f0729b0ef (patch)
treed4831170cd6c5373f0daab7589e70a4821c9099d /arch/powerpc/kernel
parent01227a889ed56ae53aeebb9f93be9d54dd8b2de8 (diff)
powerpc: Emulate non privileged DSCR read and write
POWER8 allows read and write of the DSCR in userspace. We added kernel emulation so applications could always use the instructions regardless of the CPU type. Unfortunately there are two SPRs for the DSCR and we only added emulation for the privileged one. Add code to match the non privileged one. A simple test was created to verify the fix: http://ozlabs.org/~anton/junkcode/user_dscr_test.c Without the patch we get a SIGILL and it passes with the patch. Signed-off-by: Anton Blanchard <anton@samba.org> Cc: <stable@kernel.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel')
-rw-r--r--arch/powerpc/kernel/traps.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 37cc40ef5043..83efa2f7d926 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -970,7 +970,10 @@ static int emulate_instruction(struct pt_regs *regs)
#ifdef CONFIG_PPC64
/* Emulate the mfspr rD, DSCR. */
- if (((instword & PPC_INST_MFSPR_DSCR_MASK) == PPC_INST_MFSPR_DSCR) &&
+ if ((((instword & PPC_INST_MFSPR_DSCR_USER_MASK) ==
+ PPC_INST_MFSPR_DSCR_USER) ||
+ ((instword & PPC_INST_MFSPR_DSCR_MASK) ==
+ PPC_INST_MFSPR_DSCR)) &&
cpu_has_feature(CPU_FTR_DSCR)) {
PPC_WARN_EMULATED(mfdscr, regs);
rd = (instword >> 21) & 0x1f;
@@ -978,7 +981,10 @@ static int emulate_instruction(struct pt_regs *regs)
return 0;
}
/* Emulate the mtspr DSCR, rD. */
- if (((instword & PPC_INST_MTSPR_DSCR_MASK) == PPC_INST_MTSPR_DSCR) &&
+ if ((((instword & PPC_INST_MTSPR_DSCR_USER_MASK) ==
+ PPC_INST_MTSPR_DSCR_USER) ||
+ ((instword & PPC_INST_MTSPR_DSCR_MASK) ==
+ PPC_INST_MTSPR_DSCR)) &&
cpu_has_feature(CPU_FTR_DSCR)) {
PPC_WARN_EMULATED(mtdscr, regs);
rd = (instword >> 21) & 0x1f;