Re: [PATCH] lib/sstep: Fix incorrect return from analyze_instr()
On 1/23/21 6:03 AM, Michael Ellerman wrote: Ananth N Mavinakayanahalli writes: We currently just percolate the return value from analyze_instr() to the caller of emulate_step(), especially if it is a -1. For one particular case (opcode = 4) for instructions that aren't currently emulated, we are returning 'should not be single-stepped' while we should have returned 0 which says 'did not emulate, may have to single-step'. Signed-off-by: Ananth N Mavinakayanahalli Tested-by: Naveen N. Rao --- arch/powerpc/lib/sstep.c | 49 +- 1 file changed, 27 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index 5a425a4a1d88..a3a0373843cd 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1445,34 +1445,39 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #ifdef __powerpc64__ case 4: - if (!cpu_has_feature(CPU_FTR_ARCH_300)) - return -1; - - switch (word & 0x3f) { - case 48:/* maddhd */ - asm volatile(PPC_MADDHD(%0, %1, %2, %3) : -"=r" (op->val) : "r" (regs->gpr[ra]), -"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); - goto compute_done; + /* +* There are very many instructions with this primary opcode +* introduced in the ISA as early as v2.03. However, the ones +* we currently emulate were all introduced with ISA 3.0 +*/ + if (cpu_has_feature(CPU_FTR_ARCH_300)) { + switch (word & 0x3f) { + case 48:/* maddhd */ + asm volatile(PPC_MADDHD(%0, %1, %2, %3) : +"=r" (op->val) : "r" (regs->gpr[ra]), +"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); + goto compute_done; Indenting everything makes this patch harder to read, and I think makes the resulting code harder to read too. We already have two levels of switch here, and we're inside a ~1700 line function, so keeping things simple is important I think. Doesn't this achieve the same result? diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index bf7a7d62ae8b..d631baaf1da2 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1443,8 +1443,10 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #ifdef __powerpc64__ case 4: - if (!cpu_has_feature(CPU_FTR_ARCH_300)) - return -1; + if (!cpu_has_feature(CPU_FTR_ARCH_300)) { + op->type = UNKNOWN; + return 0; + } switch (word & 0x3f) { case 48:/* maddhd */ @@ -1470,7 +1472,8 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, * There are other instructions from ISA 3.0 with the same * primary opcode which do not have emulation support yet. */ - return -1; + op->type = UNKNOWN; + return 0; #endif case 7: /* mulli */ Looks good to me. Acked-by: Ananth N Mavinakayanahalli -- Ananth
Re: [PATCH] lib/sstep: Fix incorrect return from analyze_instr()
Ananth N Mavinakayanahalli writes: > We currently just percolate the return value from analyze_instr() > to the caller of emulate_step(), especially if it is a -1. > > For one particular case (opcode = 4) for instructions that > aren't currently emulated, we are returning 'should not be > single-stepped' while we should have returned 0 which says > 'did not emulate, may have to single-step'. > > Signed-off-by: Ananth N Mavinakayanahalli > Tested-by: Naveen N. Rao > --- > arch/powerpc/lib/sstep.c | 49 > +- > 1 file changed, 27 insertions(+), 22 deletions(-) > > diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c > index 5a425a4a1d88..a3a0373843cd 100644 > --- a/arch/powerpc/lib/sstep.c > +++ b/arch/powerpc/lib/sstep.c > @@ -1445,34 +1445,39 @@ int analyse_instr(struct instruction_op *op, const > struct pt_regs *regs, > > #ifdef __powerpc64__ > case 4: > - if (!cpu_has_feature(CPU_FTR_ARCH_300)) > - return -1; > - > - switch (word & 0x3f) { > - case 48:/* maddhd */ > - asm volatile(PPC_MADDHD(%0, %1, %2, %3) : > - "=r" (op->val) : "r" (regs->gpr[ra]), > - "r" (regs->gpr[rb]), "r" (regs->gpr[rc])); > - goto compute_done; > + /* > + * There are very many instructions with this primary opcode > + * introduced in the ISA as early as v2.03. However, the ones > + * we currently emulate were all introduced with ISA 3.0 > + */ > + if (cpu_has_feature(CPU_FTR_ARCH_300)) { > + switch (word & 0x3f) { > + case 48:/* maddhd */ > + asm volatile(PPC_MADDHD(%0, %1, %2, %3) : > + "=r" (op->val) : "r" > (regs->gpr[ra]), > + "r" (regs->gpr[rb]), "r" > (regs->gpr[rc])); > + goto compute_done; Indenting everything makes this patch harder to read, and I think makes the resulting code harder to read too. We already have two levels of switch here, and we're inside a ~1700 line function, so keeping things simple is important I think. Doesn't this achieve the same result? diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index bf7a7d62ae8b..d631baaf1da2 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1443,8 +1443,10 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #ifdef __powerpc64__ case 4: - if (!cpu_has_feature(CPU_FTR_ARCH_300)) - return -1; + if (!cpu_has_feature(CPU_FTR_ARCH_300)) { + op->type = UNKNOWN; + return 0; + } switch (word & 0x3f) { case 48:/* maddhd */ @@ -1470,7 +1472,8 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, * There are other instructions from ISA 3.0 with the same * primary opcode which do not have emulation support yet. */ - return -1; + op->type = UNKNOWN; + return 0; #endif case 7: /* mulli */ cheers
Re: [PATCH] lib/sstep: Fix incorrect return from analyze_instr()
On 21/01/21 10:18 pm, Ananth N Mavinakayanahalli wrote: > We currently just percolate the return value from analyze_instr() > to the caller of emulate_step(), especially if it is a -1. > > For one particular case (opcode = 4) for instructions that > aren't currently emulated, we are returning 'should not be > single-stepped' while we should have returned 0 which says > 'did not emulate, may have to single-step'. > > Signed-off-by: Ananth N Mavinakayanahalli > Tested-by: Naveen N. Rao > --- > arch/powerpc/lib/sstep.c | 49 > +- > 1 file changed, 27 insertions(+), 22 deletions(-) > Thanks for fixing this. Reviewed-by: Sandipan Das
Re: [PATCH] lib/sstep: Fix incorrect return from analyze_instr()
On 2021/01/21 10:18PM, Ananth N Mavinakayanahalli wrote: > We currently just percolate the return value from analyze_instr() > to the caller of emulate_step(), especially if it is a -1. > > For one particular case (opcode = 4) for instructions that > aren't currently emulated, we are returning 'should not be > single-stepped' while we should have returned 0 which says > 'did not emulate, may have to single-step'. > > Signed-off-by: Ananth N Mavinakayanahalli > Tested-by: Naveen N. Rao > --- > arch/powerpc/lib/sstep.c | 49 > +- > 1 file changed, 27 insertions(+), 22 deletions(-) Fixes: 930d6288a26787 ("powerpc: sstep: Add support for maddhd, maddhdu, maddld instructions") Reviewed-by: Naveen N. Rao < naveen.n@linux.vnet.ibm.com> - Naveen
[PATCH] lib/sstep: Fix incorrect return from analyze_instr()
We currently just percolate the return value from analyze_instr() to the caller of emulate_step(), especially if it is a -1. For one particular case (opcode = 4) for instructions that aren't currently emulated, we are returning 'should not be single-stepped' while we should have returned 0 which says 'did not emulate, may have to single-step'. Signed-off-by: Ananth N Mavinakayanahalli Tested-by: Naveen N. Rao --- arch/powerpc/lib/sstep.c | 49 +- 1 file changed, 27 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index 5a425a4a1d88..a3a0373843cd 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1445,34 +1445,39 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #ifdef __powerpc64__ case 4: - if (!cpu_has_feature(CPU_FTR_ARCH_300)) - return -1; - - switch (word & 0x3f) { - case 48:/* maddhd */ - asm volatile(PPC_MADDHD(%0, %1, %2, %3) : -"=r" (op->val) : "r" (regs->gpr[ra]), -"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); - goto compute_done; + /* +* There are very many instructions with this primary opcode +* introduced in the ISA as early as v2.03. However, the ones +* we currently emulate were all introduced with ISA 3.0 +*/ + if (cpu_has_feature(CPU_FTR_ARCH_300)) { + switch (word & 0x3f) { + case 48:/* maddhd */ + asm volatile(PPC_MADDHD(%0, %1, %2, %3) : +"=r" (op->val) : "r" (regs->gpr[ra]), +"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); + goto compute_done; - case 49:/* maddhdu */ - asm volatile(PPC_MADDHDU(%0, %1, %2, %3) : -"=r" (op->val) : "r" (regs->gpr[ra]), -"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); - goto compute_done; + case 49:/* maddhdu */ + asm volatile(PPC_MADDHDU(%0, %1, %2, %3) : +"=r" (op->val) : "r" (regs->gpr[ra]), +"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); + goto compute_done; - case 51:/* maddld */ - asm volatile(PPC_MADDLD(%0, %1, %2, %3) : -"=r" (op->val) : "r" (regs->gpr[ra]), -"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); - goto compute_done; + case 51:/* maddld */ + asm volatile(PPC_MADDLD(%0, %1, %2, %3) : +"=r" (op->val) : "r" (regs->gpr[ra]), +"r" (regs->gpr[rb]), "r" (regs->gpr[rc])); + goto compute_done; + } } /* -* There are other instructions from ISA 3.0 with the same -* primary opcode which do not have emulation support yet. +* Rest of the instructions with this primary opcode do not +* have emulation support yet. */ - return -1; + op->type = UNKNOWN; + return 0; #endif case 7: /* mulli */