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authorVineet Gupta <vgupta@synopsys.com>2017-04-20 15:36:51 -0700
committerVineet Gupta <vgupta@synopsys.com>2017-04-20 15:37:49 -0700
commit3d5e80125a6e5649c6bdad8d5780e39ea422c67d (patch)
tree5db65bfac17a6dbbff36d055b0292e9addeb8d90 /arch/arc
parent6492f09e864417d382e22b922ae30693a7ce2982 (diff)
downloadlinux-3d5e80125a6e5649c6bdad8d5780e39ea422c67d.tar.bz2
ARCv2: entry: save Accumulator register pair (r58:59) if present
Accumulator is present in configs with FPU and/or DSP MPY (mpy > 6) Instead of doing this in pt_regs (and thus every kernel entry/exit), this could have been done in context switch (and for user task only) as currently kernel doesn't clobber these registers for its own accord. However we will soon start using 64-bit multiply instructions for kernel which can clobber these. Also gcc folks also plan to start using these as GPRs, hence better to always save/restore them Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/Kconfig8
-rw-r--r--arch/arc/include/asm/entry-arcv2.h10
-rw-r--r--arch/arc/include/asm/ptrace.h4
-rw-r--r--arch/arc/kernel/setup.c30
4 files changed, 43 insertions, 9 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index c9f30f4763ab..5d7fb3e7cb97 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -406,6 +406,14 @@ config ARC_HAS_DIV_REM
bool "Insn: div, divu, rem, remu"
default y
+config ARC_HAS_ACCL_REGS
+ bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6)"
+ default n
+ help
+ Depending on the configuration, CPU can contain accumulator reg-pair
+ (also referred to as r58:r59). These can also be used by gcc as GPR so
+ kernel needs to save/restore per process
+
endif # ISA_ARCV2
endmenu # "ARC CPU Configuration"
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index aee1a77934cf..ac85380d14a4 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -16,6 +16,11 @@
;
; Now manually save: r12, sp, fp, gp, r25
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+ PUSH r59
+ PUSH r58
+#endif
+
PUSH r30
PUSH r12
@@ -75,6 +80,11 @@
POP r12
POP r30
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+ POP r58
+ POP r59
+#endif
+
.endm
/*------------------------------------------------------------------------*/
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 47111d565a95..5297faa8a378 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -86,6 +86,10 @@ struct pt_regs {
unsigned long r12, r30;
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+ unsigned long r58, r59; /* ACCL/ACCH used by FPU / DSP MPY */
+#endif
+
/*------- Below list auto saved by h/w -----------*/
unsigned long r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11;
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index fa62404ba58f..fc8211f338ad 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -319,7 +319,8 @@ static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
static void arc_chk_core_config(void)
{
struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
- int fpu_enabled;
+ int saved = 0, present = 0;
+ char *opt_nm = NULL;;
if (!cpu->extn.timer0)
panic("Timer0 is not present!\n");
@@ -346,17 +347,28 @@ static void arc_chk_core_config(void)
/*
* FP hardware/software config sanity
- * -If hardware contains DPFP, kernel needs to save/restore FPU state
+ * -If hardware present, kernel needs to save/restore FPU state
* -If not, it will crash trying to save/restore the non-existant regs
- *
- * (only DPDP checked since SP has no arch visible regs)
*/
- fpu_enabled = IS_ENABLED(CONFIG_ARC_FPU_SAVE_RESTORE);
- if (cpu->extn.fpu_dp && !fpu_enabled)
- pr_warn("CONFIG_ARC_FPU_SAVE_RESTORE needed for working apps\n");
- else if (!cpu->extn.fpu_dp && fpu_enabled)
- panic("FPU non-existent, disable CONFIG_ARC_FPU_SAVE_RESTORE\n");
+ if (is_isa_arcompact()) {
+ opt_nm = "CONFIG_ARC_FPU_SAVE_RESTORE";
+ saved = IS_ENABLED(CONFIG_ARC_FPU_SAVE_RESTORE);
+
+ /* only DPDP checked since SP has no arch visible regs */
+ present = cpu->extn.fpu_dp;
+ } else {
+ opt_nm = "CONFIG_ARC_HAS_ACCL_REGS";
+ saved = IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS);
+
+ /* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
+ present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
+ }
+
+ if (present && !saved)
+ pr_warn("Enable %s for working apps\n", opt_nm);
+ else if (!present && saved)
+ panic("Disable %s, hardware NOT present\n", opt_nm);
}
/*