| Message ID | 20190610193215.23704-6-julien.grall@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/arm64: Rework head.S to make it more compliant with the Arm Arm | expand |
On Mon, 10 Jun 2019, Julien Grall wrote: > At the moment, the user should save x30/lr if it cares about it. > > Follow-up patches will introduce more use of putn in place where lr > should be preserved. > > Furthermore, any user of putn should also move the value to register x0 > if it was stored in a different register. > > For convenience, a new macro is introduced to print a given register. > The macro will take care for us to move the value to x0 and also > preserve lr. > > Lastly the new macro is used to replace all the callsite of putn. This > will simplify rework/review later on. > > Note that CurrentEL is now stored in x5 instead of x4 because the latter > will be clobbered by the macro print_reg. > > Signed-off-by: Julien Grall <julien.grall@arm.com> > --- > xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++------- > 1 file changed, 22 insertions(+), 7 deletions(-) > > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > index 84e26582c4..9142b4a774 100644 > --- a/xen/arch/arm/arm64/head.S > +++ b/xen/arch/arm/arm64/head.S > @@ -90,8 +90,25 @@ > bl puts ; \ > mov lr, x3 ; \ > RODATA_STR(98, _s) > + > +/* > + * Macro to print the value of register \xb > + * > + * Clobbers x0 - x4 > + */ > +.macro print_reg xb > + mov x4, lr > + mov x0, \xb > + bl putn > + mov lr, x4 I have the same weird issues with my compiler as before, replacing 'lr' with 'x30' solves the problem. This patch looks OK though. > +.endm > + > #else /* CONFIG_EARLY_PRINTK */ > #define PRINT(s) > + > +.macro print_reg xb > +.endm > + > #endif /* !CONFIG_EARLY_PRINTK */ > > /* Load the physical address of a symbol into xb */ > @@ -304,22 +321,20 @@ GLOBAL(init_secondary) > #ifdef CONFIG_EARLY_PRINTK > ldr x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */ > PRINT("- CPU ") > - mov x0, x24 > - bl putn > + print_reg x24 > PRINT(" booting -\r\n") > #endif > > common_start: > > PRINT("- Current EL ") > - mrs x4, CurrentEL > - mov x0, x4 > - bl putn > + mrs x5, CurrentEL > + print_reg x5 > PRINT(" -\r\n") > > /* Are we in EL2 */ > - cmp x4, #PSR_MODE_EL2t > - ccmp x4, #PSR_MODE_EL2h, #0x4, ne > + cmp x5, #PSR_MODE_EL2t > + ccmp x5, #PSR_MODE_EL2h, #0x4, ne > b.eq el2 /* Yes */ > > /* OK, we're boned. */ > -- > 2.11.0 >
Hi Stefano, On 26/06/2019 01:09, Stefano Stabellini wrote: > On Mon, 10 Jun 2019, Julien Grall wrote: >> At the moment, the user should save x30/lr if it cares about it. >> >> Follow-up patches will introduce more use of putn in place where lr >> should be preserved. >> >> Furthermore, any user of putn should also move the value to register x0 >> if it was stored in a different register. >> >> For convenience, a new macro is introduced to print a given register. >> The macro will take care for us to move the value to x0 and also >> preserve lr. >> >> Lastly the new macro is used to replace all the callsite of putn. This >> will simplify rework/review later on. >> >> Note that CurrentEL is now stored in x5 instead of x4 because the latter >> will be clobbered by the macro print_reg. >> >> Signed-off-by: Julien Grall <julien.grall@arm.com> >> --- >> xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++------- >> 1 file changed, 22 insertions(+), 7 deletions(-) >> >> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S >> index 84e26582c4..9142b4a774 100644 >> --- a/xen/arch/arm/arm64/head.S >> +++ b/xen/arch/arm/arm64/head.S >> @@ -90,8 +90,25 @@ >> bl puts ; \ >> mov lr, x3 ; \ >> RODATA_STR(98, _s) >> + >> +/* >> + * Macro to print the value of register \xb >> + * >> + * Clobbers x0 - x4 >> + */ >> +.macro print_reg xb >> + mov x4, lr >> + mov x0, \xb >> + bl putn >> + mov lr, x4 > > I have the same weird issues with my compiler as before, replacing 'lr' > with 'x30' solves the problem. Can you have a try with the following line? lr .req x30 // link register Cheers,
Hi Julien, Julien Grall writes: > At the moment, the user should save x30/lr if it cares about it. > > Follow-up patches will introduce more use of putn in place where lr > should be preserved. > > Furthermore, any user of putn should also move the value to register x0 > if it was stored in a different register. > > For convenience, a new macro is introduced to print a given register. > The macro will take care for us to move the value to x0 and also > preserve lr. > > Lastly the new macro is used to replace all the callsite of putn. This > will simplify rework/review later on. > > Note that CurrentEL is now stored in x5 instead of x4 because the latter > will be clobbered by the macro print_reg. > > Signed-off-by: Julien Grall <julien.grall@arm.com> > --- > xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++------- > 1 file changed, 22 insertions(+), 7 deletions(-) > > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > index 84e26582c4..9142b4a774 100644 > --- a/xen/arch/arm/arm64/head.S > +++ b/xen/arch/arm/arm64/head.S > @@ -90,8 +90,25 @@ > bl puts ; \ > mov lr, x3 ; \ > RODATA_STR(98, _s) > + > +/* > + * Macro to print the value of register \xb > + * > + * Clobbers x0 - x4 > + */ Despite its name, this macro can't print x4. I would recommend adding at least comment about this. Static assertion would be even better, but looks like we don't have them for asm code. > +.macro print_reg xb > + mov x4, lr > + mov x0, \xb > + bl putn > + mov lr, x4 > +.endm > + > #else /* CONFIG_EARLY_PRINTK */ > #define PRINT(s) > + > +.macro print_reg xb > +.endm > + > #endif /* !CONFIG_EARLY_PRINTK */ > > /* Load the physical address of a symbol into xb */ > @@ -304,22 +321,20 @@ GLOBAL(init_secondary) > #ifdef CONFIG_EARLY_PRINTK > ldr x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */ > PRINT("- CPU ") > - mov x0, x24 > - bl putn > + print_reg x24 > PRINT(" booting -\r\n") > #endif > > common_start: > > PRINT("- Current EL ") > - mrs x4, CurrentEL > - mov x0, x4 > - bl putn > + mrs x5, CurrentEL > + print_reg x5 > PRINT(" -\r\n") > > /* Are we in EL2 */ > - cmp x4, #PSR_MODE_EL2t > - ccmp x4, #PSR_MODE_EL2h, #0x4, ne > + cmp x5, #PSR_MODE_EL2t > + ccmp x5, #PSR_MODE_EL2h, #0x4, ne > b.eq el2 /* Yes */ > > /* OK, we're boned. */ -- Best regards, Volodymyr Babchuk
On 7/15/19 7:46 PM, Volodymyr Babchuk wrote: > Hi Julien, Hi, > Julien Grall writes: > >> At the moment, the user should save x30/lr if it cares about it. >> >> Follow-up patches will introduce more use of putn in place where lr >> should be preserved. >> >> Furthermore, any user of putn should also move the value to register x0 >> if it was stored in a different register. >> >> For convenience, a new macro is introduced to print a given register. >> The macro will take care for us to move the value to x0 and also >> preserve lr. >> >> Lastly the new macro is used to replace all the callsite of putn. This >> will simplify rework/review later on. >> >> Note that CurrentEL is now stored in x5 instead of x4 because the latter >> will be clobbered by the macro print_reg. >> >> Signed-off-by: Julien Grall <julien.grall@arm.com> >> --- >> xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++------- >> 1 file changed, 22 insertions(+), 7 deletions(-) >> >> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S >> index 84e26582c4..9142b4a774 100644 >> --- a/xen/arch/arm/arm64/head.S >> +++ b/xen/arch/arm/arm64/head.S >> @@ -90,8 +90,25 @@ >> bl puts ; \ >> mov lr, x3 ; \ >> RODATA_STR(98, _s) >> + >> +/* >> + * Macro to print the value of register \xb >> + * >> + * Clobbers x0 - x4 >> + */ > > Despite its name, this macro can't print x4. I would recommend adding at > least comment about this. Static assertion would be even better, but > looks like we don't have them for asm code. I have a new version of the function allowing to print x4. It is basically just swapping "mov x4, lr" with "mov x0, \xb". > >> +.macro print_reg xb >> + mov x4, lr >> + mov x0, \xb >> + bl putn >> + mov lr, x4 >> +.endm >> + >> #else /* CONFIG_EARLY_PRINTK */ >> #define PRINT(s) Cheers,
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 84e26582c4..9142b4a774 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -90,8 +90,25 @@ bl puts ; \ mov lr, x3 ; \ RODATA_STR(98, _s) + +/* + * Macro to print the value of register \xb + * + * Clobbers x0 - x4 + */ +.macro print_reg xb + mov x4, lr + mov x0, \xb + bl putn + mov lr, x4 +.endm + #else /* CONFIG_EARLY_PRINTK */ #define PRINT(s) + +.macro print_reg xb +.endm + #endif /* !CONFIG_EARLY_PRINTK */ /* Load the physical address of a symbol into xb */ @@ -304,22 +321,20 @@ GLOBAL(init_secondary) #ifdef CONFIG_EARLY_PRINTK ldr x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */ PRINT("- CPU ") - mov x0, x24 - bl putn + print_reg x24 PRINT(" booting -\r\n") #endif common_start: PRINT("- Current EL ") - mrs x4, CurrentEL - mov x0, x4 - bl putn + mrs x5, CurrentEL + print_reg x5 PRINT(" -\r\n") /* Are we in EL2 */ - cmp x4, #PSR_MODE_EL2t - ccmp x4, #PSR_MODE_EL2h, #0x4, ne + cmp x5, #PSR_MODE_EL2t + ccmp x5, #PSR_MODE_EL2h, #0x4, ne b.eq el2 /* Yes */ /* OK, we're boned. */
At the moment, the user should save x30/lr if it cares about it. Follow-up patches will introduce more use of putn in place where lr should be preserved. Furthermore, any user of putn should also move the value to register x0 if it was stored in a different register. For convenience, a new macro is introduced to print a given register. The macro will take care for us to move the value to x0 and also preserve lr. Lastly the new macro is used to replace all the callsite of putn. This will simplify rework/review later on. Note that CurrentEL is now stored in x5 instead of x4 because the latter will be clobbered by the macro print_reg. Signed-off-by: Julien Grall <julien.grall@arm.com> --- xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-)