From: Corey Minyard <cminyard@xxxxxxxxxx> Modify the SAVE_SOME macro to look more like a standard function, doing the arithmetic for the frame on the SP register instead of copying it from K1, and by saving the stored EPC from the RA. This lets the get_frame_info() function process this function like any other. It also remove an instruction or two from the kernel entry, making it more efficient. unwind_stack_by_address() has special handling for the top of the interrupt stack, but without this change unwinding will still fail if you get an interrupt while handling an interrupt and try to do a traceback from the second interrupt. This change modifies the get_saved_sp macro to optionally store the fetched value right into sp and store the old SP value into K0. Then it's just a matter of subtracting the frame from SP and storing the old SP from K0. This required changing the DADDI workaround a bit, since K0 holds the SP, we had to use K1 for AT. But it eliminated some of the special handling for the DADDI workaround. Saving the RA register was moved up to before fetching the CP0_EPC register, so the CP0_EPC register could be stored into RA and the saved. This lets the traceback code know where RA is actually stored. Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx> --- arch/mips/include/asm/stackframe.h | 51 +++++++++++++++++++++++++++----------- 1 file changed, 37 insertions(+), 14 deletions(-) diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h index eaa5a4d..d2fb919 100644 --- a/arch/mips/include/asm/stackframe.h +++ b/arch/mips/include/asm/stackframe.h @@ -83,8 +83,16 @@ LONG_S $30, PT_R30(sp) .endm +/* + * get_saved_sp returns the SP for the current CPU by looking in the + * kernelsp array for it. If tosp is set, it stores the current sp in + * k0 and loads the new value in sp. If not, it clobbers k0 and + * stores the new value in k1, leaving sp unaffected. + */ #ifdef CONFIG_SMP - .macro get_saved_sp /* SMP variation */ + + /* SMP variation */ + .macro get_saved_sp docfi=0 tosp=0 ASM_CPUID_MFC0 k0, ASM_SMP_CPUID_REG #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32) lui k1, %hi(kernelsp) @@ -97,7 +105,15 @@ #endif LONG_SRL k0, SMP_CPUID_PTRSHIFT LONG_ADDU k1, k0 + .if \tosp + move k0, sp + .if \docfi + .cfi_register sp, k0 + .endif + LONG_L sp, %lo(kernelsp)(k1) + .else LONG_L k1, %lo(kernelsp)(k1) + .endif .endm .macro set_saved_sp stackp temp temp2 @@ -106,7 +122,8 @@ LONG_S \stackp, kernelsp(\temp) .endm #else /* !CONFIG_SMP */ - .macro get_saved_sp /* Uniprocessor variation */ + /* Uniprocessor variation */ + .macro get_saved_sp docfi=0 tosp=0 #ifdef CONFIG_CPU_JUMP_WORKAROUNDS /* * Clear BTB (branch target buffer), forbid RAS (return address @@ -135,7 +152,15 @@ daddiu k1, %hi(kernelsp) dsll k1, k1, 16 #endif + .if \tosp + move k0, sp + .if \docfi + .cfi_register sp, k0 + .endif + LONG_L sp, %lo(kernelsp)(k1) + .else LONG_L k1, %lo(kernelsp)(k1) + .endif .endm .macro set_saved_sp stackp temp temp2 @@ -151,7 +176,6 @@ sll k0, 3 /* extract cu0 bit */ .set noreorder bltz k0, 8f - move k1, sp #ifdef CONFIG_EVA /* * Flush interAptiv's Return Prediction Stack (RPS) by writing @@ -178,17 +202,16 @@ MTC0 k0, CP0_ENTRYHI #endif .set reorder + move k0, sp /* Called from user mode, new stack. */ get_saved_sp -#ifndef CONFIG_CPU_DADDI_WORKAROUNDS -8: move k0, sp - PTR_SUBU sp, k1, PT_SIZE -#else - .set at=k0 -8: PTR_SUBU k1, PT_SIZE +8: +#ifdef CONFIG_CPU_DADDI_WORKAROUNDS + .set at=k1 +#endif + PTR_SUBU sp, PT_SIZE +#ifdef CONFIG_CPU_DADDI_WORKAROUNDS .set noat - move k0, sp - move sp, k1 #endif LONG_S k0, PT_R29(sp) LONG_S $3, PT_R3(sp) @@ -206,16 +229,16 @@ LONG_S $5, PT_R5(sp) LONG_S v1, PT_CAUSE(sp) LONG_S $6, PT_R6(sp) - MFC0 v1, CP0_EPC + LONG_S ra, PT_R31(sp) + MFC0 ra, CP0_EPC LONG_S $7, PT_R7(sp) #ifdef CONFIG_64BIT LONG_S $8, PT_R8(sp) LONG_S $9, PT_R9(sp) #endif - LONG_S v1, PT_EPC(sp) + LONG_S ra, PT_EPC(sp) LONG_S $25, PT_R25(sp) LONG_S $28, PT_R28(sp) - LONG_S $31, PT_R31(sp) /* Set thread_info if we're coming from user mode */ mfc0 k0, CP0_STATUS -- 2.7.4
