| Message ID | 1610454557-25867-5-git-send-email-hejinyang@loongson.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | MIPS: process: Some fixes and improvements about get_frame_info() | expand |
On Tue, 12 Jan 2021, Jinyang He wrote: > For those leaf functions, they are likely to have no stack operations. > Add is_jr_ra_ins() to determine whether jr ra has been touched before > the frame_size is found. Without this patch, the get frame_size operation > may be out of range and get the frame_size from the next nested function. > > Signed-off-by: Jinyang He <hejinyang@loongson.cn> > --- > arch/mips/kernel/process.c | 34 +++++++++++++++++++++++++++++++++- > 1 file changed, 33 insertions(+), 1 deletion(-) > > diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c > index bef8f8d..9e6f194 100644 > --- a/arch/mips/kernel/process.c > +++ b/arch/mips/kernel/process.c > @@ -205,6 +205,36 @@ struct mips_frame_info { > #define J_TARGET(pc,target) \ > (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) > > +static inline int is_jr_ra_ins(union mips_instruction *ip) > +{ > +#ifdef CONFIG_CPU_MICROMIPS > + /* > + * jr16 ra > + * jr ra > + */ > + if (mm_insn_16bit(ip->word >> 16)) { > + if (ip->mm16_r5_format.opcode == mm_pool16c_op && > + ip->mm16_r5_format.rt == mm_jr16_op && > + ip->mm16_r5_format.imm == 31) > + return 1; > + return 0; > + } > + > + if (ip->r_format.opcode == mm_pool32a_op && > + ip->r_format.func == mm_pool32axf_op && > + ((ip->u_format.uimmediate >> 6) & GENMASK(9,0)) == mm_jalr_op && > + ip->r_format.rs == 31) > + return 1; > + return 0; > +#else Without looking into it much, this is likely missing the point, because while technically inteed JR and JR16 can be used with $ra in microMIPS machine code (there's JRS too), in reality either JRC or JRADDIUSP will. [Wading through e-mail recovered from mid-Jan linux-mips.org crash.] Maciej
On 10/24/2021 02:32 AM, Maciej W. Rozycki wrote: > On Tue, 12 Jan 2021, Jinyang He wrote: > >> For those leaf functions, they are likely to have no stack operations. >> Add is_jr_ra_ins() to determine whether jr ra has been touched before >> the frame_size is found. Without this patch, the get frame_size operation >> may be out of range and get the frame_size from the next nested function. >> >> Signed-off-by: Jinyang He <hejinyang@loongson.cn> >> --- >> arch/mips/kernel/process.c | 34 +++++++++++++++++++++++++++++++++- >> 1 file changed, 33 insertions(+), 1 deletion(-) >> >> diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c >> index bef8f8d..9e6f194 100644 >> --- a/arch/mips/kernel/process.c >> +++ b/arch/mips/kernel/process.c >> @@ -205,6 +205,36 @@ struct mips_frame_info { >> #define J_TARGET(pc,target) \ >> (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) >> >> +static inline int is_jr_ra_ins(union mips_instruction *ip) >> +{ >> +#ifdef CONFIG_CPU_MICROMIPS >> + /* >> + * jr16 ra >> + * jr ra >> + */ >> + if (mm_insn_16bit(ip->word >> 16)) { >> + if (ip->mm16_r5_format.opcode == mm_pool16c_op && >> + ip->mm16_r5_format.rt == mm_jr16_op && >> + ip->mm16_r5_format.imm == 31) >> + return 1; >> + return 0; >> + } >> + >> + if (ip->r_format.opcode == mm_pool32a_op && >> + ip->r_format.func == mm_pool32axf_op && >> + ((ip->u_format.uimmediate >> 6) & GENMASK(9,0)) == mm_jalr_op && >> + ip->r_format.rs == 31) >> + return 1; >> + return 0; >> +#else > Without looking into it much, this is likely missing the point, because > while technically inteed JR and JR16 can be used with $ra in microMIPS > machine code (there's JRS too), in reality either JRC or JRADDIUSP will. > > [Wading through e-mail recovered from mid-Jan linux-mips.org crash.] > > Maciej You are right, I missed the point. I have refered to microMIPS64 Instruction Set. JRC and JRADDIUSP also can be used with $ra in microMIPS. I am not sure what compiler do at epilogue. But when we call $ra without saving $ra, it means return, I think. I will fix it later. Thanks, Jinyang.
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index bef8f8d..9e6f194 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -205,6 +205,36 @@ struct mips_frame_info { #define J_TARGET(pc,target) \ (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) +static inline int is_jr_ra_ins(union mips_instruction *ip) +{ +#ifdef CONFIG_CPU_MICROMIPS + /* + * jr16 ra + * jr ra + */ + if (mm_insn_16bit(ip->word >> 16)) { + if (ip->mm16_r5_format.opcode == mm_pool16c_op && + ip->mm16_r5_format.rt == mm_jr16_op && + ip->mm16_r5_format.imm == 31) + return 1; + return 0; + } + + if (ip->r_format.opcode == mm_pool32a_op && + ip->r_format.func == mm_pool32axf_op && + ((ip->u_format.uimmediate >> 6) & GENMASK(9,0)) == mm_jalr_op && + ip->r_format.rs == 31) + return 1; + return 0; +#else + if (ip->r_format.opcode == spec_op && + ip->r_format.func == jr_op && + ip->r_format.rs == 31) + return 1; + return 0; +#endif +} + static inline int is_ra_save_ins(union mips_instruction *ip, int *poff) { #ifdef CONFIG_CPU_MICROMIPS @@ -417,7 +447,9 @@ static int get_frame_info(struct mips_frame_info *info) last_insn_size = 4; } - if (!info->frame_size) { + if (is_jr_ra_ins(ip)) { + break; + } else if (!info->frame_size) { is_sp_move_ins(&insn, &info->frame_size); continue; } else if (!saw_jump && is_jump_ins(ip)) {
For those leaf functions, they are likely to have no stack operations. Add is_jr_ra_ins() to determine whether jr ra has been touched before the frame_size is found. Without this patch, the get frame_size operation may be out of range and get the frame_size from the next nested function. Signed-off-by: Jinyang He <hejinyang@loongson.cn> --- arch/mips/kernel/process.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-)