From: Indu Bhagat <indu.bhagat@oracle.com>
To: binutils@sourceware.org
Cc: Richard.Earnshaw@arm.com, Indu Bhagat <indu.bhagat@oracle.com>
Subject: [PATCH,V2 1/7] gas: scfi: make scfi_state_restore_reg function more precise
Date: Sat, 1 Jun 2024 00:34:50 -0700 [thread overview]
Message-ID: <20240601073456.2715287-2-indu.bhagat@oracle.com> (raw)
In-Reply-To: <20240601073456.2715287-1-indu.bhagat@oracle.com>
[New in V2]
- This patch is orthogonal to aarch64 support. It is included here
because the testcase added for it is aarch64 specific. It is a
bugfix really.
[End of New in V2]
When the SCFI machinery detects that a register has been restored from
stack, it makes some state changes in the SCFI state object.
Prior to the patch, scfi_state_restore_reg () was setting a value of
(reg, CFI_IN_REG) for (base, state) respectively. This was causing
issues in the cmp_scfi_state () function:
- The default state of all (callee-saved) regs at the beginning of
function is set to (0, CFI_UNDEFINED).
- If a register is saved and restored on some control path, the state
of reg is (reg, CFI_IN_REG) on that path.
- On another control path where the register was perhaps not
used (or saved/restored on stack) remains (0, CFI_UNDEFINED).
- The two states should be treated equal, however, at the point in
program after the register has been restored.
Fix this by resetting the state to (0, CFI_UNDEFINED) in
scfi_state_restore_reg ().
A testcase (scfi-cfg-4.s) for this is added in a subsequent commit.
gas/
* scfi.c (scfi_state_restore_reg): Reset to 0, CFI_UNDEFINED
for base, state.
---
gas/scfi.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/gas/scfi.c b/gas/scfi.c
index 744822d8102..5898a57b330 100644
--- a/gas/scfi.c
+++ b/gas/scfi.c
@@ -223,11 +223,12 @@ scfi_state_restore_reg (scfi_stateS *state, unsigned int reg)
gas_assert (state->regs[reg].state == CFI_ON_STACK);
gas_assert (state->regs[reg].base == REG_CFA);
- state->regs[reg].base = reg;
+ /* PS: the register may still be on stack much after the restore. Reset the
+ SCFI state to CFI_UNDEFINED, however, to indicate that the most updated
+ source of value is register itself from here onwards. */
+ state->regs[reg].base = 0;
state->regs[reg].offset = 0;
- /* PS: the register may still be on stack much after the restore, but the
- SCFI state keeps the state as 'in register'. */
- state->regs[reg].state = CFI_IN_REG;
+ state->regs[reg].state = CFI_UNDEFINED;
}
/* Identify if the given GAS instruction GINSN saves a register
--
2.43.0
next prev parent reply other threads:[~2024-06-01 7:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-01 7:34 [PATCH,V2 0/7] Add SCFI support for aarch64 Indu Bhagat
2024-06-01 7:34 ` Indu Bhagat [this message]
2024-06-06 16:09 ` [PATCH, V2 1/7] gas: scfi: make scfi_state_restore_reg function more precise Richard Earnshaw (lists)
2024-07-01 0:56 ` Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 2/7] opcodes: aarch64: flags to denote subclasses of ldst insns Indu Bhagat
2024-06-06 16:50 ` [PATCH, V2 " Richard Earnshaw (lists)
2024-06-06 20:31 ` Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 3/7] opcodes: aarch64: allow FLAGS in CPA_INSN, CPA_SVE_INSNC Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 4/7] opcodes: aarch64: flags to denote subclasses of arithmetic insns Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 5/7] opcodes: aarch64: flags to denote subclasses of uncond branches Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 6/7] gas: aarch64: add experimental support for SCFI Indu Bhagat
2024-06-01 7:34 ` [PATCH,V2 7/7] gas: aarch64: testsuite: add new tests " Indu Bhagat
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