| Message ID | Ztbk0Vk35dDGLoCd@p100 (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | target/hppa: Fix PSW V-bit packaging in cpu_hppa_get for hppa64 | expand |
On 9/3/24 03:28, Helge Deller wrote: > While adding hppa64 support, the psw_v variable got extended from 32 to 64 > bits. So, when packaging the PSW-V bit from the psw_v variable for interrupt > processing, check bit 31 instead the 63th (sign) bit. > > This fixes a hard to find Linux kernel boot issue where the loss of the PSW-V > bit due to an ITLB interruption in the middle of a series of ds/addc > instructions (from the divU milicode library) generated the wrong division > result and thus triggered a Linux kernel crash. > > Link: https://lore.kernel.org/lkml/718b8afe-222f-4b3a-96d3-93af0e4ceff1@roeck-us.net/ > Reported-by: Guenter Roeck <linux@roeck-us.net> > Signed-off-by: Helge Deller <deller@gmx.de> > Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64") Tested-by: Guenter Roeck <linux@roeck-us.net> Thanks! Guenter > > diff --git a/target/hppa/helper.c b/target/hppa/helper.c > index b79ddd8184..d4b1a3cd5a 100644 > --- a/target/hppa/helper.c > +++ b/target/hppa/helper.c > @@ -53,7 +53,7 @@ target_ulong cpu_hppa_get_psw(CPUHPPAState *env) > } > > psw |= env->psw_n * PSW_N; > - psw |= (env->psw_v < 0) * PSW_V; > + psw |= ((env->psw_v >> 31) & 1) * PSW_V; > psw |= env->psw | env->psw_xb; > > return psw;
On 9/3/24 03:28, Helge Deller wrote: > While adding hppa64 support, the psw_v variable got extended from 32 to 64 > bits. So, when packaging the PSW-V bit from the psw_v variable for interrupt > processing, check bit 31 instead the 63th (sign) bit. > > This fixes a hard to find Linux kernel boot issue where the loss of the PSW-V > bit due to an ITLB interruption in the middle of a series of ds/addc > instructions (from the divU milicode library) generated the wrong division > result and thus triggered a Linux kernel crash. > > Link: https://lore.kernel.org/lkml/718b8afe-222f-4b3a-96d3-93af0e4ceff1@roeck-us.net/ > Reported-by: Guenter Roeck <linux@roeck-us.net> > Signed-off-by: Helge Deller <deller@gmx.de> > Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64") > > diff --git a/target/hppa/helper.c b/target/hppa/helper.c > index b79ddd8184..d4b1a3cd5a 100644 > --- a/target/hppa/helper.c > +++ b/target/hppa/helper.c > @@ -53,7 +53,7 @@ target_ulong cpu_hppa_get_psw(CPUHPPAState *env) > } > > psw |= env->psw_n * PSW_N; > - psw |= (env->psw_v < 0) * PSW_V; > + psw |= ((env->psw_v >> 31) & 1) * PSW_V; > psw |= env->psw | env->psw_xb; > > return psw; While this is correct, we should also update cpu.h: - target_long psw_v; /* in most significant bit */ + target_long psw_v; /* in bit 31 */ With that, Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/target/hppa/helper.c b/target/hppa/helper.c index b79ddd8184..d4b1a3cd5a 100644 --- a/target/hppa/helper.c +++ b/target/hppa/helper.c @@ -53,7 +53,7 @@ target_ulong cpu_hppa_get_psw(CPUHPPAState *env) } psw |= env->psw_n * PSW_N; - psw |= (env->psw_v < 0) * PSW_V; + psw |= ((env->psw_v >> 31) & 1) * PSW_V; psw |= env->psw | env->psw_xb; return psw;
While adding hppa64 support, the psw_v variable got extended from 32 to 64 bits. So, when packaging the PSW-V bit from the psw_v variable for interrupt processing, check bit 31 instead the 63th (sign) bit. This fixes a hard to find Linux kernel boot issue where the loss of the PSW-V bit due to an ITLB interruption in the middle of a series of ds/addc instructions (from the divU milicode library) generated the wrong division result and thus triggered a Linux kernel crash. Link: https://lore.kernel.org/lkml/718b8afe-222f-4b3a-96d3-93af0e4ceff1@roeck-us.net/ Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Helge Deller <deller@gmx.de> Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64")