Displaying 11 results from an estimated 11 matches for "ideal_nop".
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ideal_nops
2017 Oct 04
1
[RFC v3 20/27] x86/ftrace: Adapt function tracing for PIE support
...(unsigned long ip, unsigned long addr)
+static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr,
+ unsigned int size)
{
static union ftrace_code_union calc;
+ /* On PIE, fill the rest of the buffer with nops */
+ if (IS_ENABLED(CONFIG_X86_PIE))
+ memset(calc.code, ideal_nops[1][0], sizeof(calc.code));
+
calc.e8 = 0xe8;
- calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
+ calc.offset = ftrace_calc_offset(ip + MCOUNT_RELINSN_SIZE, addr);
/*
* No locking needed, this must be called via kstop_machine
@@ -72,6 +77,44 @@ static unsigned char *ftrace_...
2012 Feb 14
3
ftrace_enabled set to 1 on bootup, slow downs with CONFIG_FUNCTION_TRACER in virt environments?
Hey,
I was running some benchmarks (netserver/netperf) where the init script just launched
the netserver and nothing else and was concerned to see the performance not up to par.
This was an HVM guest running with PV drivers.
If I compile the kernel without CONFIG_FUNCTION_TRACER it is much better - but it was
my understanding that the tracing code does not impact the machine unless it is
2018 May 23
0
[PATCH v3 21/27] x86/ftrace: Adapt function tracing for PIE support
...)
+ return ftrace_modify_code_direct(ip, old_code, new_code);
+
+ /*
+ * Build a nop slide with a 5-byte nop and 1-byte nop to keep the ftrace
+ * hooking algorithm working with the expected 5 bytes instruction.
+ */
+ memcpy(replaced, new_code, MCOUNT_INSN_SIZE);
+ replaced[MCOUNT_INSN_SIZE] = ideal_nops[1][0];
+
+ ip = text_ip_addr(ip);
+
+ if (probe_kernel_write((void *)ip, replaced, sizeof(replaced)))
+ return -EPERM;
+
+ sync_core();
+
+ return 0;
+
+}
+
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
@@ -153,7 +191,7 @@ int ftrace_make_nop(struc...
2018 Mar 13
0
[PATCH v2 21/27] x86/ftrace: Adapt function tracing for PIE support
...)
+ return ftrace_modify_code_direct(ip, old_code, new_code);
+
+ /*
+ * Build a nop slide with a 5-byte nop and 1-byte nop to keep the ftrace
+ * hooking algorithm working with the expected 5 bytes instruction.
+ */
+ memcpy(replaced, new_code, MCOUNT_INSN_SIZE);
+ replaced[MCOUNT_INSN_SIZE] = ideal_nops[1][0];
+
+ ip = text_ip_addr(ip);
+
+ if (probe_kernel_write((void *)ip, replaced, sizeof(replaced)))
+ return -EPERM;
+
+ sync_core();
+
+ return 0;
+
+}
+
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
@@ -153,7 +191,7 @@ int ftrace_make_nop(struc...
2017 Oct 04
28
x86: PIE support and option to extend KASLR randomization
These patches make the changes necessary to build the kernel as Position
Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below
the top 2G of the virtual address space. It allows to optionally extend the
KASLR randomization range from 1G to 3G.
Thanks a lot to Ard Biesheuvel & Kees Cook on their feedback on compiler
changes, PIE support and KASLR in general. Thanks to
2017 Oct 04
28
x86: PIE support and option to extend KASLR randomization
These patches make the changes necessary to build the kernel as Position
Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below
the top 2G of the virtual address space. It allows to optionally extend the
KASLR randomization range from 1G to 3G.
Thanks a lot to Ard Biesheuvel & Kees Cook on their feedback on compiler
changes, PIE support and KASLR in general. Thanks to
2018 Mar 13
32
[PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization
Changes:
- patch v2:
- Adapt patch to work post KPTI and compiler changes
- Redo all performance testing with latest configs and compilers
- Simplify mov macro on PIE (MOVABS now)
- Reduce GOT footprint
- patch v1:
- Simplify ftrace implementation.
- Use gcc mstack-protector-guard-reg=%gs with PIE when possible.
- rfc v3:
- Use --emit-relocs instead of -pie to reduce
2018 Mar 13
32
[PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization
Changes:
- patch v2:
- Adapt patch to work post KPTI and compiler changes
- Redo all performance testing with latest configs and compilers
- Simplify mov macro on PIE (MOVABS now)
- Reduce GOT footprint
- patch v1:
- Simplify ftrace implementation.
- Use gcc mstack-protector-guard-reg=%gs with PIE when possible.
- rfc v3:
- Use --emit-relocs instead of -pie to reduce
2018 May 23
33
[PATCH v3 00/27] x86: PIE support and option to extend KASLR randomization
Changes:
- patch v3:
- Update on message to describe longer term PIE goal.
- Minor change on ftrace if condition.
- Changed code using xchgq.
- patch v2:
- Adapt patch to work post KPTI and compiler changes
- Redo all performance testing with latest configs and compilers
- Simplify mov macro on PIE (MOVABS now)
- Reduce GOT footprint
- patch v1:
- Simplify ftrace
2017 Oct 11
32
[PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization
Changes:
- patch v1:
- Simplify ftrace implementation.
- Use gcc mstack-protector-guard-reg=%gs with PIE when possible.
- rfc v3:
- Use --emit-relocs instead of -pie to reduce dynamic relocation space on
mapped memory. It also simplifies the relocation process.
- Move the start the module section next to the kernel. Remove the need for
-mcmodel=large on modules. Extends
2017 Oct 11
32
[PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization
Changes:
- patch v1:
- Simplify ftrace implementation.
- Use gcc mstack-protector-guard-reg=%gs with PIE when possible.
- rfc v3:
- Use --emit-relocs instead of -pie to reduce dynamic relocation space on
mapped memory. It also simplifies the relocation process.
- Move the start the module section next to the kernel. Remove the need for
-mcmodel=large on modules. Extends