Re: [PATCH v1 2/2] powerpc: Enable OPTPROBES on PPC32
From: Christophe Leroy
Date: Tue Apr 20 2021 - 09:37:15 EST
Le 20/04/2021 à 08:51, Naveen N. Rao a écrit :
Christophe Leroy wrote:
For that, create a 32 bits version of patch_imm64_load_insns()
and create a patch_imm_load_insns() which calls
patch_imm32_load_insns() on PPC32 and patch_imm64_load_insns()
on PPC64.
Adapt optprobes_head.S for PPC32. Use PPC_LL/PPC_STL macros instead
of raw ld/std, opt out things linked to paca and use stmw/lmw to
save/restore registers.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/Kconfig | 2 +-
arch/powerpc/kernel/optprobes.c | 24 +++++++++++++--
arch/powerpc/kernel/optprobes_head.S | 46 +++++++++++++++++++---------
3 files changed, 53 insertions(+), 19 deletions(-)
Thanks for adding support for ppc32. It is good to see that it works without too many changes.
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c1344c05226c..49b538e54efb 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -227,7 +227,7 @@ config PPC
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI if PERF_EVENTS || (PPC64 && PPC_BOOK3S)
select HAVE_HARDLOCKUP_DETECTOR_ARCH if PPC64 && PPC_BOOK3S && SMP
- select HAVE_OPTPROBES if PPC64
+ select HAVE_OPTPROBES
select HAVE_PERF_EVENTS
select HAVE_PERF_EVENTS_NMI if PPC64
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI &&
!HAVE_HARDLOCKUP_DETECTOR_ARCH
diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index 58fdb9f66e0f..cdf87086fa33 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -141,11 +141,21 @@ void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
}
}
+static void patch_imm32_load_insns(unsigned long val, int reg, kprobe_opcode_t *addr)
+{
+ patch_instruction((struct ppc_inst *)addr,
+ ppc_inst(PPC_RAW_LIS(reg, IMM_H(val))));
+ addr++;
+
+ patch_instruction((struct ppc_inst *)addr,
+ ppc_inst(PPC_RAW_ORI(reg, reg, IMM_L(val))));
+}
+
/*
* Generate instructions to load provided immediate 64-bit value
* to register 'reg' and patch these instructions at 'addr'.
*/
-static void patch_imm64_load_insns(unsigned long val, int reg, kprobe_opcode_t *addr)
+static void patch_imm64_load_insns(unsigned long long val, int reg, kprobe_opcode_t *addr)
Do you really need this?
Without it I get:
from arch/powerpc/kernel/optprobes.c:8:
arch/powerpc/kernel/optprobes.c: In function 'patch_imm64_load_insns':
arch/powerpc/kernel/optprobes.c:163:14: error: right shift count >= width of type
[-Werror=shift-count-overflow]
163 | ((val >> 48) & 0xffff)));
| ^~
./arch/powerpc/include/asm/inst.h:69:48: note: in definition of macro 'ppc_inst'
69 | #define ppc_inst(x) ((struct ppc_inst){ .val = x })
| ^
arch/powerpc/kernel/optprobes.c:169:31: error: right shift count >= width of type
[-Werror=shift-count-overflow]
169 | ___PPC_RS(reg) | ((val >> 32) & 0xffff)));
| ^~
./arch/powerpc/include/asm/inst.h:69:48: note: in definition of macro 'ppc_inst'
69 | #define ppc_inst(x) ((struct ppc_inst){ .val = x })
| ^
{
/* lis reg,(op)@highest */
patch_instruction((struct ppc_inst *)addr,
@@ -177,6 +187,14 @@ static void patch_imm64_load_insns(unsigned long val, int reg, kprobe_opcode_t *
___PPC_RS(reg) | (val & 0xffff)));
}
+static void patch_imm_load_insns(unsigned long val, int reg, kprobe_opcode_t *addr)
+{
+ if (IS_ENABLED(CONFIG_PPC64))
+ patch_imm64_load_insns(val, reg, addr);
+ else
+ patch_imm32_load_insns(val, reg, addr);
+}
+
int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
{
struct ppc_inst branch_op_callback, branch_emulate_step, temp;
@@ -230,7 +248,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
* Fixup the template with instructions to:
* 1. load the address of the actual probepoint
*/
- patch_imm64_load_insns((unsigned long)op, 3, buff + TMPL_OP_IDX);
+ patch_imm_load_insns((unsigned long)op, 3, buff + TMPL_OP_IDX);
/*
* 2. branch to optimized_callback() and emulate_step()
@@ -264,7 +282,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
* 3. load instruction to be emulated into relevant register, and
*/
temp = ppc_inst_read((struct ppc_inst *)p->ainsn.insn);
- patch_imm64_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX);
+ patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX);
/*
* 4. branch back from trampoline
diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S
index ff8ba4d3824d..49f31e554573 100644
--- a/arch/powerpc/kernel/optprobes_head.S
+++ b/arch/powerpc/kernel/optprobes_head.S
@@ -30,39 +30,47 @@ optinsn_slot:
.global optprobe_template_entry
optprobe_template_entry:
/* Create an in-memory pt_regs */
- stdu r1,-INT_FRAME_SIZE(r1)
+ PPC_STLU r1,-INT_FRAME_SIZE(r1)
SAVE_GPR(0,r1)
/* Save the previous SP into stack */
addi r0,r1,INT_FRAME_SIZE
- std r0,GPR1(r1)
+ PPC_STL r0,GPR1(r1)
+#ifdef CONFIG_PPC64
SAVE_10GPRS(2,r1)
SAVE_10GPRS(12,r1)
SAVE_10GPRS(22,r1)
+#else
+ stmw r2, GPR2(r1)
+#endif
/* Save SPRS */
mfmsr r5
- std r5,_MSR(r1)
+ PPC_STL r5,_MSR(r1)
li r5,0x700
- std r5,_TRAP(r1)
+ PPC_STL r5,_TRAP(r1)
li r5,0
- std r5,ORIG_GPR3(r1)
- std r5,RESULT(r1)
+ PPC_STL r5,ORIG_GPR3(r1)
+ PPC_STL r5,RESULT(r1)
mfctr r5
- std r5,_CTR(r1)
+ PPC_STL r5,_CTR(r1)
mflr r5
- std r5,_LINK(r1)
+ PPC_STL r5,_LINK(r1)
mfspr r5,SPRN_XER
- std r5,_XER(r1)
+ PPC_STL r5,_XER(r1)
mfcr r5
- std r5,_CCR(r1)
+ PPC_STL r5,_CCR(r1)
+#ifdef CONFIG_PPC64
lbz r5,PACAIRQSOFTMASK(r13)
std r5,SOFTE(r1)
+#endif
/*
* We may get here from a module, so load the kernel TOC in r2.
* The original TOC gets restored when pt_regs is restored
* further below.
*/
+#ifdef CONFIG_PPC64
ld r2,PACATOC(r13)
+#endif
Are the ISA and ABI documents for ppc32 available publicly?
ABI: https://wiki.raptorcs.com/w/images/0/03/Power-Arch-32-bit-ABI-supp-1.0-Unified.pdf
ISA: https://www.nxp.com/files-static/product/doc/MPCFPE32B.pdf
I would have thought that the TOC issues
apply to ppc32 as well, but want to understand why this isn't a problem there.
r2 is the pointer to 'current' on PPC32.
No TOC.
.global optprobe_template_op_address
optprobe_template_op_address:
@@ -72,9 +80,11 @@ optprobe_template_op_address:
*/
nop
nop
+#ifdef CONFIG_PPC64
nop
nop
nop
+#endif
/* 2. pt_regs pointer in r4 */
addi r4,r1,STACK_FRAME_OVERHEAD
@@ -94,9 +104,11 @@ optprobe_template_insn:
/* 2, Pass instruction to be emulated in r4 */
nop
nop
+#ifdef CONFIG_PPC64
nop
nop
nop
+#endif
It would be nice to put these behind a macro so as to avoid these #ifdef blocks here, as well as
with the register save/restore sequence.
Will see what I can do
Christophe