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authorAnton Blanchard <anton@samba.org>2013-05-01 20:06:33 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-11 07:18:16 -0700
commit5e701b123c0d3c58c01d3168de9ef11d86eea34d (patch)
tree2e510a7a8ac8866978c7b91a0f62fec9f749ad5a /arch
parentb6356ec0a242fd362019bd1f08680fb8f413af4a (diff)
powerpc: Emulate non privileged DSCR read and write
commit 73d2fb758e678c93bc76d40876c2359f0729b0ef upstream. 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> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/ppc-opcode.h4
-rw-r--r--arch/powerpc/kernel/traps.c10
2 files changed, 12 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 8752bc8e34a3..8cbc6e54e4c4 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -113,6 +113,10 @@
#define PPC_INST_MFSPR_DSCR_MASK 0xfc1fffff
#define PPC_INST_MTSPR_DSCR 0x7c1103a6
#define PPC_INST_MTSPR_DSCR_MASK 0xfc1fffff
+#define PPC_INST_MFSPR_DSCR_USER 0x7c0302a6
+#define PPC_INST_MFSPR_DSCR_USER_MASK 0xfc1fffff
+#define PPC_INST_MTSPR_DSCR_USER 0x7c0303a6
+#define PPC_INST_MTSPR_DSCR_USER_MASK 0xfc1fffff
#define PPC_INST_SLBFEE 0x7c0007a7
#define PPC_INST_STRING 0x7c00042a
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;